Terminals, base stations, and communication methods

Abstract

A terminal according to the present invention comprises: a control circuit that, on the basis of a control signal pertaining to uplink transmission, determines a transmission opportunity, using a cell-specific offset or a parameter differing from the cell-specific offset; and a transmission circuit that carries out uplink transmission at the transmission opportunity.

Description

[Technical Field]

[0001] This disclosure relates to terminals, base stations, and communication methods. [Background technology]

[0002] In the standardization of 5G, new radio access technology (NR) was discussed at 3GPP, and the NR Release 15 (Rel.15) specification was published. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP, TR 38.821, V16.0.0 “Solutions for NR to support non-terrestrial networks (NTN) (Release 16)”, 2019-12 [Non-Patent Document 2] 3GPP, TS 38.321, V16.3.0 “Medium Access Control (MAC) protocol specification (Release 16)”, 2020-12 [Overview of the project]

[0004] However, there is room for consideration regarding appropriate timing control in response to propagation delays between terminals and base stations.

[0005] Non-limiting embodiments of this disclosure contribute to providing a terminal, base station, and communication method that can achieve appropriate timing control in response to propagation delay between the terminal and the base station.

[0006] A terminal according to one embodiment of the present disclosure comprises a control circuit that determines a transmission opportunity based on a control signal for uplink transmission using either a cell-specific offset or a parameter different from the cell-specific offset, and a transmission circuit that performs the uplink transmission at the transmission opportunity.

[0007] These comprehensive or specific embodiments may be implemented as systems, devices, methods, integrated circuits, computer programs, or recording media, or as any combination of systems, devices, methods, integrated circuits, computer programs, and recording media.

[0008] According to one embodiment of this disclosure, appropriate timing control can be achieved in response to the propagation delay between the terminal and the base station.

[0009] Further advantages and effects of one aspect of this disclosure will be made apparent from the specification and drawings. Such advantages and / or effects are provided by several embodiments and features described in the specification and drawings, but not all of them are necessarily provided in order to obtain one or more identical features. [Brief explanation of the drawing]

[0010] [Figure 1] A diagram showing an example of transmission slot timing. [Figure 2] A diagram showing an example of propagation delay within a satellite cell. [Figure 3] A diagram showing an example of cell-specific offset and terminal-specific offset. [Figure 4] This figure shows an example of applying an offset to the PDCCH order RACH. [Figure 5] Block diagram showing some example configurations of base stations. [Figure 6] Block diagram showing some example configurations of the terminal. [Figure 7] Block diagram showing an example of a base station configuration. [Figure 8] Block diagram showing an example of terminal configuration [Figure 9] Figure showing an example of the transmission timing of PDCCH order RACH according to Embodiment 1 [Figure 10] Figure showing an example of the relationship between the offset and RACH Occasion (RO) according to Embodiment 1 [Figure 11] Figure showing an example of the transmission timing of PDCCH order RACH according to Embodiment 3 [Figure 12] Figure showing an example of the transmission timing of PDCCH order RACH according to Embodiment 3 [Figure 13] Figure showing an example of the transmission timing of PDCCH order RACH according to Embodiment 3 [Figure 14] Figure of an exemplary architecture of the 3GPP NR system [Figure 15] Schematic diagram showing the functional separation between NG-RAN and 5GC [Figure 16] Sequence diagram of the procedure for RRC connection setup / reconfiguration [Figure 17] Schematic diagram showing the usage scenarios of large-capacity and high-speed communication (eMBB: enhanced Mobile BroadBand), massive machine type communication (mMTC: massive Machine Type Communications), and ultra-reliable and low-latency communication (URLLC: Ultra Reliable and Low Latency Communications) [Figure 18] Block diagram showing an exemplary 5G system architecture for non-roaming scenarios [Embodiments for Carrying Out the Invention]

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] [Expansion to a non-terrestrial network (NTN: Non-Terrestrial Network)] Rel.15 is specified as a wireless access technology for terrestrial networks. On the other hand, NR is being considered for extension to non-terrestrial networks (NTN), such as communications using satellites or high-altitude platform stations (HAPS) (for example, Non-Patent Document 1).

[0013] In an NTN environment, the satellite's coverage area (e.g., one or more cells) for ground-based terminals (e.g., also called user equipment (UE)) or terminals located in the air, such as aircraft or drones, is formed by beams from the satellite. The round-trip time (RTT) for radio wave propagation between the terminal and the satellite is determined by the satellite's altitude (e.g., up to approximately 36,000 km) or the angle from the terminal, i.e., the relative positions of the satellite and the terminal.

[0014] For example, Non-Patent Literature 1 states that NTN's round-trip time (RTT) for radio wave propagation between a base station (also known as a gNB) and a terminal can take up to approximately 540 ms. Non-Patent Literature 1 also states that a maximum delay difference of approximately 10 ms can occur depending on the location of the terminal within the beam (cell). The maximum delay difference may be, for example, the difference between the round-trip time between the terminal furthest from the satellite and the satellite itself, and the round-trip time between the terminal closest to the satellite and the satellite itself.

[0015] [Random Access Procedure] In 5G NR, terminals use a Random Access Channel (RACH) for initial access and data transmission requests. For example, the random access procedure may be implemented using a four-step random access (also called 4-step RACH or 4-Step CBRA (Contention Based Random Access)).

[0016] In 4-stage random access, the terminal transmits a PRACH (Physical Random Access Channel) Preamble signal to the base station during the first stage of transmission (MSG1). The MSG1 transmission by the terminal is performed at the transmission timing (slot timing or RACH Occasion (RO)) notified individually by the base station. In the following, transmitting a PRACH signal (e.g., a Preamble signal) may be abbreviated as "transmitting PRACH" or "transmitting PRACH." Similarly, receiving a PRACH signal may be described as "receiving PRACH" or "receiving PRACH." The transmission and reception of signals on other channels may also be abbreviated in a similar manner.

[0017] The base station receives and decodes MSG1, and in the second stage of transmission (MSG2), notifies the terminal of scheduling information including the response to the PRACH Preamble signal (Random Access response (RAR)) and the uplink transmission timing of MSG3.

[0018] The terminal receives and decodes MSG2, and in the third stage transmission (MSG3), uses the scheduling information instructed by MSG2 to notify the base station of information necessary for establishing a connection, such as information about the terminal (e.g., terminal ID). MSG3 may be notified, for example, on an uplink data channel (e.g., Physical Uplink Shared Channel (PUSCH)). The information notified by MSG3 may be called RRC (Radio Resource Control) connection request information.

[0019] The base station receives and decodes MSG3, and in the fourth stage transmission (MSG4), it notifies the base station of a connection establishment response, etc.

[0020] [Timing adjustment] In 5G NR, the transmission timing of terminals is controlled so that signals from different terminals within a cell are received at the base station within a certain time frame. For example, this time frame can be within the Cyclic Prefix (CP) of an OFDM (Orthogonal Frequency Division Multiplexing) signal or a DFT-S-OFDM (Discrete Fourier Transform-Spread-OFDM) signal.

[0021] In random access procedures, the terminal transmits MSG1 at candidate PRACH transmission timings (RACH Occasions) notified individually by the base station for each cell. Here, the terminal determines its transmission timing based on the reception timing of a synchronization signal called SSB (SS (Synchronization Signal) / PBCH (Physical Broadcast Channel) Block) transmitted from the base station on the downlink. Therefore, depending on the propagation delay between the base station and the terminal, the reception timing at the base station may differ from the reception timing assumed by the base station. Here, the reception timing assumed by the base station is, for example, the reception timing determined based on candidate PRACH transmission timings (RACH Occasions) notified individually by the base station for each cell.

[0022] In response to a deviation from the reception timing expected by the base station, the base station may, for example, send information to the terminal in MSG2 to correct (adjust) the timing. This information for correcting (adjusting) the timing may be called a TA (Timing Advance) command (see, for example, Non-Patent Document 2). The terminal corrects the transmission timing of MSG3 and subsequent signals based on the TA command included in MSG2. The base station may also send a TA command to the terminal if it detects a deviation in reception timing during the transmission and reception of signals from MSG3 onward.

[0023] Furthermore, in 5G NR, RACH transmission may be triggered by the base station not only during initial access, but also in situations where there is a possibility of terminal desynchronization, such as when a terminal has not communicated for a while while connected to a base station (e.g., in the RRC_CONNECTED state), or when the TA timer expires, or when downlink transmission data destined for the terminal arrives. This RACH transmission may be triggered using, for example, the downlink control channel (e.g., Physical Downlink Shared Channel (PDCCH)). RACH transmission triggered using PDCCH is called, for example, "PDCCH order RACH" (an example will be described later).

[0024] In NTN, because communication between base stations and terminals is long-distance, the propagation delay between base stations and terminals is larger compared to terrestrial cellular systems, and the difference in propagation delay between terminals is also larger. Therefore, for example, it is being considered that terminals calculate the propagation delay based on the distance between the terminal and the satellite estimated using terminal position information obtained by GNSS (Global Navigation Satellite System) and satellite position information obtained from satellite orbit information (satellite ephemeris), and then autonomously adjust the timing of the terminal.

[0025] Furthermore, in 5G NR, the timing of the transmission slot is specified in Rel.15.

[0026] Figure 1 shows an example of transmit slot timing. Figure 1 shows an example of transmit slot timing in terrestrial cellular networks as defined in Rel. 15 (Figure 1(a)) and an example of transmit slot timing being considered by NTN (Figure 1(b)).

[0027] Figure 1 also illustrates the DL transmit slot and UL receive slot of a base station (gNB), and the DL receive slot and UL transmit slot of a terminal (UE). The horizontal axis in Figure 1 represents the time axis.

[0028] In NR Rel.15 (e.g., terrestrial cellular), the transmission timing of UL signals such as HARQ-ACK (hybrid automatic repeat request - acknowledgement) or PUSCH may be defined based on the transmission slot timing (e.g., also called the reference slot) of DL signals such as downlink control information (e.g., Downlink Control Information (DCI)) or downlink data signals (e.g., Physical Downlink Shared Channel (PDSCH)). For example, the transmission timing of UL signals may be defined using an offset from the transmission slot (e.g., also called the reference slot) of DL signals.

[0029] Examples of offsets include "K1," which indicates the timing offset from PDSCH to HARQ-ACK, and "K2," which indicates the timing offset from DCI to PUSCH. The timing offset K1 from PDSCH to HARQ-ACK transmission is sometimes called the "PDSCH-to-HARQ_feedback timing indicator." In Figure 1(a), according to the Rel.15 transmission slot timing specification, in the nth slot, a signal including DCI is transmitted from the base station to the terminal, and in the n+K2th slot, the PUSCH signal is transmitted from the terminal to the base station.

[0030] On the other hand, as shown in Figure 1(b), NTN is considering setting an offset "Koffset" to compensate for the longer propagation delay compared to terrestrial cellular networks, in relation to the Rel.15 transmission slot timing specifications.

[0031] A base station may specify the timing (e.g., slot) for receiving the UL signal at the base station, for example, by Koffset. The UL signal may include, for example, uplink control information (UCI) such as HARQ-ACK, or a PUSCH signal containing uplink data signals.

[0032] Koffset can include, for example, cell-specific Koffsets that are notified (or reported) individually to each cell (e.g., "K offset,cell (represented as "), and terminal-specific (UE-specific) Koffset(K offset,UE ) will be considered. Furthermore, in the following, K offset,cell and K offset,UE It is sometimes abbreviated as "Koffset".

[0033] For example, the cell-specific Koffset may be set based on the RTT at the location within the cell where the propagation delay (e.g., D_cell) between the satellite (or base station) and the terminal is greatest, as shown in Figure 2. The cell-specific Koffset may be broadcast to the entire cell, for example, by including it in the system information. The terminal-specific Koffset may be set individually for each terminal (UE) based on the terminal's location or propagation delay amount (e.g., D_UE), as shown in Figure 2. The terminal-specific Koffset may be notified to each terminal individually, for example.

[0034] Figure 3 shows an example of transmit slot timing based on terminal-specific Koffset. In Figure 3, for example, the base station (gNB) transmits DCI at the time (slot n) and then calculates the slot after the offset K2 and terminal-specific Koffset (for example, slot (n + K2 + K offset,UE The timing of the terminal's (UE) PUSCH transmission may be set so that it receives PUSCH in )).

[0035] As shown in Figure 3, timing adjustment based on terminal-specific Koffsets can reduce data transmission delays compared to timing adjustment based on cell-specific Koffsets, for example, because it is based on terminal-specific RTT.

[0036] [PDCCH order RACH] NR Rel.15 specifies that the PDCCH order RACH, for example, is defined as a terminal receiving a PDCCH that triggers the transmission of PRACH, and then transmitting PRACH in the "next available RO".

[0037] In terrestrial networks, compared to NTN, propagation delay is shorter and transmission and reception timings are almost simultaneous, so the possibility of a difference in the recognition of the "next available RO" between the base station and the terminal is extremely low.

[0038] On the other hand, NTN experiences longer propagation delays compared to terrestrial networks, making it easier for base stations and terminals to misjudge the "next available RO." For this reason, NTN is considering introducing Koffset for PRACH transmission. By introducing Koffset, the RO will be determined according to the propagation delay, thus reducing the likelihood of misjudgments in the recognition of the "next available RO" between base stations and terminals.

[0039] However, since PDCCH order RACH can also be applied when a terminal is in the RRC_CONNECTED state but the base station does not identify (in other words, understand) the terminal's synchronization status, if a terminal with a terminal-specific Koffset is set and moves far from the location where the Koffset was set, the terminal's PRACH transmission may not be in time to reach the RO specified by the terminal-specific Koffset.

[0040] Figure 4 shows an example of setting the RO in PDCCH order RACH. In Figure 4, the base station (e.g., gNB) assumes that it will receive the PRACH at a timing based on the terminal-specific Koffset, based on the transmission timing of the PDCCH that triggers the PRACH transmission. The terminal (e.g., UE) may determine the RO based on the reception timing of the PDCCH that triggers the PRACH transmission and the terminal-specific Koffset, and transmit the PRACH at the determined RO.

[0041] Here, as shown in Figure 4, if the actual location of the terminal differs from the location corresponding to the terminal-specific Koffset set on the terminal (for example, the location assumed by the base station) (for example, if the terminal is farther away from the base station (or satellite)), the timing at which the terminal actually transmits PRACH may differ from the timing of PRACH assumed by the base station (for example, it may be delayed). In other words, the terminal may not be able to transmit PRACH at the appropriate transmission timing (for example, RO) based on the terminal-specific Koffset.

[0042] Therefore, in one non-limiting embodiment of this disclosure, for example, in an environment where the propagation delay between a terminal and a base station increases, such as in an NTN environment, appropriate timing control is realized in response to the propagation delay between the terminal and the base station.

[0043] [Overview of the communication system] A communication system according to one embodiment of the present disclosure comprises a base station 100 and a terminal 200.

[0044] Figure 5 is a block diagram showing a partial configuration example of the base station 100. In the base station 100 shown in Figure 5, the control unit 109 (corresponding to, for example, a control circuit) determines a transmission opportunity based on a control signal for uplink reception, using either a cell-specific offset or a parameter different from the cell-specific offset. The wireless receiving unit 102 (corresponding to, for example, a receiving circuit) performs uplink reception during a transmission opportunity.

[0045] Figure 6 is a block diagram showing some configuration examples of terminal 200. In terminal 200 shown in Figure 6, the control unit 209 (corresponding to a control circuit, for example) determines a transmission opportunity based on a control signal for uplink transmission, using either a cell-specific offset or a parameter different from the cell-specific offset. The wireless transmission unit 205 (corresponding to a transmission circuit, for example) performs uplink transmission when a transmission opportunity arises.

[0046] (Embodiment 1) [Base station configuration] Figure 7 is a block diagram showing an example of the configuration of a base station 100 according to this embodiment. The base station 100 includes an antenna 101, a wireless receiving unit 102, a PRACH detection unit 103, a data reception processing unit 104, a timing control information generation unit 105, a data generation unit 106, a data transmission processing unit 107, and a wireless transmission unit 108. The PRACH detection unit 103, the data reception processing unit 104, the timing control information generation unit 105, the data generation unit 106, and the data transmission processing unit 107 may be included in the control unit 109.

[0047] The wireless receiver 102 performs reception processing, such as down-conversion and A / D conversion, on data signals (e.g., PUSCH), control signals (e.g., PUCCH including UCI such as HARQ-ACK), and random access signals (e.g., PRACH signals) received from the terminal 200 via the antenna 101, and outputs the processed signals to the data reception processing unit 104 and the PRACH detection unit 103.

[0048] The PRACH detection unit 103 detects the PRACH Preamble signal and estimates the transmission and reception timings based on timing information input from the timing control information generation unit 105, for example. For example, the PRACH detection unit 103 may perform correlation processing on the received PRACH Preamble signal between the sequence number corresponding to the set Preamble number and a replica signal of the Preamble signal generated using the cyclic shift amount.

[0049] The correlation processing in the PRACH detection unit 103 may be performed in the time domain to calculate the delay profile, or it may be performed in the frequency domain by performing correlation processing (division) and then IFFT (Inversed Fourier Transform) to calculate the delay profile. The calculated delay profile may be used to estimate at least one of the transmission timing and reception timing.

[0050] The PRACH detection unit 103 outputs information regarding at least one of the estimated transmission timing and reception timing to the timing control information generation unit 105. For example, the PRACH detection unit 103 may calculate the difference between the reference timing of the base station 100 and the arrival timing of the received signal, and output the calculation result to the timing control information generation unit 105.

[0051] Furthermore, the PRACH detection unit 103 may detect a PRACH (e.g., a PDCCH order RACH) that has been sent to terminal 200 as a transmission request (in other words, triggered) at a PRACH transmission timing (or transmission opportunity; for example, RO) based on the timing calculated from the timing offset. In this embodiment, for example, the PRACH detection unit 103 may detect a PRACH (e.g., a PDCCH order RACH) at an RO based on the timing calculated from the cell-specific Koffset. For example, when the PRACH detection unit 103 triggers PRACH transmission to terminal 200 by a PDCCH order RACH, it may control the PRACH reception timing using the cell-specific Koffset, regardless of the terminal-specific Koffset setting for terminal 200 (in other words, it may assume reception based on the cell-specific Koffset).

[0052] Here, for example, in a DCI for PDCCH order RACH, if "random access preamble index" is not specified, "Contention based RACH" is set, in which terminal 200 randomly selects a preamble index. In this case, the PRACH detection unit 103 may, for example, perform PRACH detection on multiple (for example, all) series set in the cell. On the other hand, for example, in a DCI for PDCCH order RACH, if "random access preamble index" is specified, "non-contention RACH" is set, in which terminal 200 sends PRACH based on the specified preamble index. In this case, the PRACH detection unit 103 may, for example, perform PRACH detection on a specified series.

[0053] Examples of PRACH transmission timing will be discussed later.

[0054] The data reception processing unit 104 performs demodulation and decoding processing on received data signals that are different from PRACH, such as PUSCH or PUCCH, based on timing information input from the timing control information generation unit 105. The data reception processing unit 104 may also perform channel estimation and timing estimation based on the received data signals. The data reception processing unit 104 outputs information regarding the estimated timing to the timing control information generation unit 105.

[0055] Here, the receiving slot for a received data signal such as PUSCH or PUCCH may be set to a timing based on the terminal-specific Koffset for terminal 200 for which a terminal-specific Koffset is set, and may be set to a timing based on the cell-specific Koffset for terminal 200 for which a terminal-specific Koffset is not set.

[0056] The timing control information generation unit 105 generates a TA command for the terminal 200 based on information output from the PRACH detection unit 103 and the data reception processing unit 104 (for example, timing estimation results). There may be multiple types of TA commands. The timing control information generation unit 105 may also generate a cell-common timing adjustment value. The cell-common timing adjustment value may be generated based on, for example, the size of the cell formed by the satellite beam, the length of the feeder link, and at least one of the feeder link delay amount.

[0057] Furthermore, the timing control information generation unit 105 may set a cell-specific Koffset based on, for example, the propagation delay amount corresponding to the location furthest from the satellite within the cell, based on at least one of the satellite's altitude and cell size. The timing control information generation unit 105 may also calculate the propagation delay amount of terminal 200 based on information regarding the terminal 200's location notified by terminal 200 and information regarding the satellite's position calculated at the base station 100 or ground gateway (GW), and set a terminal-specific Koffset based on the propagation delay amount of terminal 200. The timing control information generation unit 105 may output timing information, including the set Koffset information, to the data transmission processing unit 107, the PRACH detection unit 103, and the data reception processing unit 104.

[0058] The data generation unit 106 generates downlink data signals for the terminal 200, including user data, synchronization signals, system information (notification information), individual control information (e.g., RRC control information), MAC control information, and downlink control information (DCI). The data generation unit 106 outputs the generated downlink data signals to the data transmission processing unit 107.

[0059] The data transmission processing unit 107 encodes and modulates the downlink data signal output from the data generation unit 106 and the timing information output from the timing control information generation unit 105, and outputs the modulated signal to the wireless transmission unit 108.

[0060] The wireless transmission unit 108 performs transmission processing such as D / A conversion, upconversion, and amplification on the signal output from the data transmission processing unit 107, and transmits the processed wireless signal from the antenna 101.

[0061] [Device Configuration] Next, we will explain an example configuration for terminal 200.

[0062] Figure 8 is a block diagram showing an example of the configuration of a terminal 200 according to this embodiment. The terminal 200 includes a PRACH generation unit 201, a data generation unit 202, a location information acquisition unit 203, a timing adjustment unit 204, a wireless transmission unit 205, an antenna 206, a wireless reception unit 207, and a demodulation / decoding unit 208. The PRACH generation unit 201, the data generation unit 202, the location information acquisition unit 203, the timing adjustment unit 204, and the demodulation / decoding unit 208 may be included in the control unit 209.

[0063] The PRACH generation unit 201 determines the PRACH transmission resource from, for example, candidate PRACH transmission resources available within the cell of the base station 100. For example, the PRACH generation unit 201 sets the time and frequency resources and Preamble numbers to be used for PRACH transmission based on information about available time and frequency resources (e.g., slots and resource blocks) and Preamble number groups. Information about available time and frequency resources and Preamble number groups for PRACH transmission may be notified, for example, from the base station 100.

[0064] Here, the time and frequency resources available for sending PRACH at terminal 200 may be called RACH occasions (ROs). For example, ROs may be set individually for each SSB. For example, during initial access, terminal 200 may select a random preamble number and send PRACH at the RO corresponding to the selected SSB (e.g., the SSB with the higher received power) at the time when the cell search (in other words, SSB search) is completed. Also, for example, if a DCI that triggers a PDCCH order RACH is received in the RRC_CONNECTED state, terminal 200 may send PRACH at a timing (RO) based on the cell-specific Koffset, without using the terminal-specific Koffset.

[0065] Furthermore, for example, if no preamble number is specified in the DCI, terminal 200 may select a random preamble number and transmit a PRACH at the RO corresponding to the SSB with higher received power. On the other hand, if both a preamble number and an SSB number are specified in the DCI, terminal 200 may transmit a PRACH with the specified preamble number at the RO corresponding to the specified SSB number.

[0066] Examples of RACH transmission timing will be discussed later.

[0067] The data generation unit 202 generates an uplink transmission data stream, time and frequency resources for data signal transmission allocated from the base station 100, and data signals to be transmitted by MCS (Modulation and Coding Scheme). The time and frequency resources and MCS may be notified, for example, by downlink control information (e.g., DCI or PDCCH) (Dynamic grant) or by RRC signaling (Configured grant). The data generation unit 202 may also generate, for example, at least one of the timing adjustment results and terminal location information described later.

[0068] The location information acquisition unit 203 acquires, for example, the location information of the terminal 200 (information such as latitude, longitude, and altitude) and the location information of the communication partner's satellite. The location information acquisition unit 203 also calculates, for example, the distance between the terminal 200 and the satellite and outputs the calculated distance information to the timing adjustment unit 204. The location information of the terminal 200 and the satellite may be acquired, for example, by a GNSS function such as GPS. Alternatively, the satellite's location information may be obtained by acquiring at least one of the orbital information and time information, known as satellite ephemeris, in advance.

[0069] The timing adjustment unit 204 adjusts the reception timing of the received signal and the transmission timing of the transmitted signal. For example, the timing adjustment unit 204 adjusts the transmission timing of the transmitted signal based on at least one of the information notified or broadcast from the base station 100 (e.g., timing information) and the information calculated by the timing adjustment unit 204.

[0070] For example, the timing adjustment unit 204 uses the distance information output from the position information acquisition unit 203 and the radio wave propagation speed (approximately 3 × 10⁻¹⁰). 8 The propagation delay time between the satellite and the terminal 200 is calculated from the (m / s) value. The timing adjustment unit 204 may then adjust the transmission timing based on one or more combinations of the following: the reception timing of the signal transmitted from the base station 100, the calculated propagation delay time, the cell-common timing adjustment value and cell-specific Koffset announced by the base station 100, the individual timing adjustment value (e.g., TA value) notified to the terminal 200 by the base station 100, and the terminal-specific Koffset notified by the base station 100. The timing adjustment may vary depending on the channel and signal. For example, the timing adjustment may vary depending on PRACH, PUSCH, PUCCH, and SRS (Sounding Reference Signal).

[0071] The wireless transmission unit 205 performs transmission processing such as D / A conversion and upconversion on the signal output from the PRACH generation unit 201 and the data signal output from the data generation unit 202. The wireless transmission unit 205 transmits the processed wireless signal from the antenna 206 to the base station 100 at a transmission timing adjusted by the timing adjustment unit 204.

[0072] The wireless receiver 207 receives a received signal from the base station 100 via the antenna 206 at a reception timing adjusted by the timing adjustment unit 204. The received signal may be a downlink signal such as PDCCH or PDSCH. The received signal may also include at least one of data and control information. The wireless receiver 207 performs reception processing on the received signal, such as downconversion and A / D conversion, and outputs the processed signal to the demodulation / decoding unit 208.

[0073] The demodulation / decoding unit 208 performs demodulation and decoding of the signal output from the wireless receiver unit 207. The signal output from the wireless receiver unit 207 may include, for example, downlink signals such as PDCCH and PDSCH. PDCCH may also include, for example, PDSCH assignment information and PUSCH assignment information. PDSCH may also include, for example, user data, RRC control information, MAC CE (Control Element) control information, RACH response (e.g., MSG2), and TA commands. For example, if the demodulated and decoded information includes timing information related to transmission timing and reception timing, the demodulation / decoding unit 208 outputs the timing information to the timing adjustment unit 204.

[0074] [Example of timing adjustment] Next, we will describe an example of setting the transmission timing of PDCCH order RACH in this embodiment.

[0075] The base station 100 may calculate the longest possible round-trip propagation delay within a cell based on, for example, the satellite's altitude, the minimum elevation angle, and at least one of the assumed cell size. The base station 100 may then set a cell-specific Koffset based on the calculated propagation delay and notify the terminal 200 within the cell of the set cell-specific Koffset. The cell-specific Koffset may be notified to the terminal 200 by broadcast information such as SIB1, or by other signals.

[0076] Furthermore, for terminal 200 that has completed initial access and is in the RRC_CONNECTED state, base station 100 may estimate the round-trip propagation delay (e.g., RTT) between terminal 200 and base station 100 based on, for example, information regarding the terminal's location and information regarding propagation delay notified by terminal 200. Then, base station 100 may set a terminal-specific Koffset based on the estimated propagation delay and notify terminal 200 of the set terminal-specific Koffset. The terminal-specific Koffset may be notified to terminal 200 by, for example, at least one of RRC information, MAC CE, and DCI.

[0077] Terminal 200 may, for example, transmit an uplink signal such as PUSCH or PUCCH (e.g., HARQ-ACK) in a slot determined based on the cell-specific Koffset when no terminal-specific Koffset is set, such as when transmitting MSG3 during initial access. Terminal 200 may also, for example, transmit a PUSCH or PUCCH (e.g., HARQ-ACK) in a slot determined based on the terminal-specific Koffset after setting the terminal-specific Koffset.

[0078] Here, the radio resources (time and frequency resources) used for transmitting PRACH are called RO (RACH occasion). The slots available for PRACH transmission are called "RACH slots." For example, multiple RACH slots may be set within a frame (e.g., 10ms). Furthermore, one or more ROs may be set within a RACH slot.

[0079] The base station 100 may, for example, notify the terminal 200 of parameters (or information) related to RACH using "RACH-ConfigCommon," which is one of the RRC parameters, via SIB or RRC signaling.

[0080] For example, parameters related to the RACH slot or the RO settings within a RACH slot may be notified by "prach-ConfigurationIndex" in RACH-ConfigCommon. Also, for example, the association between SSB and RO may be notified by "ssb-perRACH-OccasionAndCB-PreamblesPerSSB" in RACH-ConfigCommon.

[0081] Furthermore, the base station 100 may, for example, trigger a PRACH transmission to terminal 200 if downlink transmission data occurs after the TA timer expires, or when there has been no communication for a certain period and the synchronization state of terminal 200 cannot be determined, for terminal 200 in the RRC_CONNECTED state. This trigger for PRACH transmission may be notified to terminal 200, for example, by DCI for PDCCH order RACH. In NR Rel. 15, for example, a trigger for PDCCH order RACH means when a specific field in DCI (e.g., resource allocation) is a specific bit sequence (e.g., all 0). Note that the trigger for PRACH transmission is not limited to this and may be by a method different from that specified in NR Rel. 15.

[0082] For DCIs for PDCCH order RACH, the following information, as described in TS38.212, may be notified, for example: - Random Access Preamble index - 6 bits according to ra-PreambleIndex - UL / SUL indicator - 1 bit. If the value of the "Random Access Preamble index" is not all zeros and if the UE is configured with supplementaryUplink in ServingCellConfig in the cell, this field indicates which UL carrier in the cell to transmit the PRACH; otherwise, this field is reserved - SS / PBCH index - 6 bits. If the value of the "Random Access Preamble index" is not all zeros, this field indicates the SS / PBCH that shall be used to determine the RACH occasion for the PRACH transmission; otherwise, this field is reserved. - PRACH Mask index - 4 bits. If the value of the "Random Access Preamble index" is not all zeros, this field indicates the RACH occasion associated with the SS / PBCH indicated by "SS / PBCH index" for the PRACH transmission,; otherwise, this field is reserved - Reserved bits - 10 bits

[0083] The base station 100 may specify a sequence of PDCCH order RACH by, for example, specifying a value other than 0 for the Random Access Preamble index (e.g., Preamble number). Furthermore, when specifying a sequence of PDCCH order RACH, the base station 100 may specify the RO using the SS / PBCH index (e.g., SSB number) and the PRACH Mask index (e.g., PRACH mask number). In this way, the base station 100 may specify the PRACH resource to be transmitted by the terminal 200.

[0084] Alternatively, the base station 100 may instruct contention-based RACH transmission by specifying 0 for the Random Access Preamble index. In this case, the terminal 200 may, for example, select a random preamble sequence and transmit PRACH on the RO associated with the SSB with higher received power.

[0085] In this embodiment, the base station 100 may set a cell-specific Koffset and a terminal-specific Koffset for the terminal 200. The terminal 200 may, for example, determine the transmission timing (e.g., RO) for a PUSCH or HARQ-ACK based on the terminal-specific Koffset. On the other hand, the terminal 200 may determine the transmission timing used for PRACH transmission for a PDCCH order RACH based on the cell-specific Koffset. In other words, when the terminal 200 is triggered to transmit a PRACH by a PDCCH from the base station 100, it may determine the transmission timing (e.g., RO) for the PRACH (e.g., PDCCH order RACH) using the cell-specific Koffset without using the terminal-specific Koffset.

[0086] Figure 9 shows an example of RO settings in PDCCH order RACH according to this embodiment.

[0087] In Figure 9, base station 100 anticipates receiving RACH at a timing based on the cell-specific Koffset, based on the transmission timing of the PDCCH that triggers RACH (e.g., PDCCH for RACH trigger).

[0088] For example, when terminal 200 receives a DCI for PDCCH order RACH (e.g., PDCCH for RACH trigger), it determines the RO based on the cell-specific Koffset, regardless of the terminal-specific Koffset setting, and sends PRACH at the determined RO. For example, terminal 200 may send PRACH at ROs from the slot specified by the cell-specific Koffset onward.

[0089] Here, for example, as shown in Figure 9, even if the actual location of terminal 200 differs from the location corresponding to the terminal-specific Koffset (e.g., propagation delay specific to terminal 200) set for terminal 200, base station 100 and terminal 200 transmit RACH based on the cell-specific Koffset. In other words, base station 100 and terminal 200 determine RO based on the timing offset based on RTT at the location within the cell where the propagation delay between the satellite (or base station 100) and terminal 200 is greatest. Therefore, regardless of the actual location of terminal 200 within the cell, the timing of PRACH transmission between base station 100 and terminal 200 can be synchronized. Furthermore, by using the cell-specific Koffset, terminal 200 can reliably transmit PRACH at the RO specified by base station 100, regardless of the location of terminal 200 within the cell (in other words, propagation delay).

[0090] In this case, multiple ROs may be configured, such as when using multiple SSBs (e.g., beamwaves). Below, we will describe two methods for determining the PRACH transmission timing based on the cell-specific Koffset, as examples.

[0091] <Decision method 1> In determination method 1, the base station 100 may receive PRACH in the first RO (e.g., an earlier RO) after the timing of the transmission slot of the PDCCH that triggers RACH plus the cell-specific Koffset (e.g., a slot delayed by the cell-specific Koffset) among the ROs corresponding to at least one of the selected SSB and preamble numbers for the terminal 200. Similarly, the terminal 200 may transmit PRACH in the first RO (e.g., an earlier RO) after the timing based on the reception slot of the PDCCH that triggers RACH and the cell-specific Koffset among the ROs corresponding to at least one of the selected SSB and preamble numbers.

[0092] Figure 10 shows an example of the relationship between cell-specific Koffset and RO when multiple ROs are set, each corresponding to multiple SSBs.

[0093] For example, when multiple ROs are set for multiple SSBs, each corresponding to a different RO, the relationship between the cell-specific Koffset and the ROs can be described as follows: 1) The slot specified by the Koffset is set before the first RO of the first SSB (e.g., the SSB with the smallest index; SSB1 in Figure 10) (RO#1 in Figure 10); 2) The slot specified by the Koffset is set after the first RO of the first SSB (e.g., the SSB with the smallest index) and before the last RO of the last SSB (e.g., the SSB with the largest index) (Case 2). For example, in the Case 2 example in Figure 10, the slot specified by the cell-specific Koffset is set after the first RO#1 of the first SSB1 and before the last RO#4 of the last SSB4 (between RO#2 and RO#3 in Figure 10).

[0094] For example, if RO#3 corresponding to SSB3 is set for terminal 200, in both Case 1 and Case 2, terminal 200 will transmit PRACH at the earlier timing corresponding to RO#3 (RO#3 corresponding to SSB3 of frame n) after the timing specified by Koffset shown in Figure 10. Similarly, base station 100 will receive (for example, assume reception) PRACH at RO#3 corresponding to SSB3 of frame n shown in Figure 10.

[0095] Thus, in determination method 1, terminal 200 may select an earlier RO (for example, an RO set for terminal 200) that is later than the timing based on the cell-specific Koffset. This allows terminal 200 to send a PRACH at an earlier timing after the timing specified by the Koffset, thereby reducing the delay until PRACH transmission.

[0096] <Decision method 2> In determination method 2, the base station 100 may receive a PRACH at an RO corresponding to at least one of the selected SSB and preamble number, such that, for example, the first RO (RO#1 in Figure 10) of the first SSB (e.g., the SSB with the lowest index; SSB1 in Figure 10) is after the transmission slot of the PDCCH that triggers the RACH and the timing slot defined by the cell-specific Koffset (e.g., a slot delayed by the cell-specific Koffset from the transmission slot of the PDCCH that triggers the RACH). Similarly, the terminal 200 may transmit a PRACH at an RO corresponding to at least one of the selected SSB and preamble number, such that, for example, the first RO of the first SSB (in other words, the first RO) is after the reception slot of the PDCCH that triggers the RACH and the timing based on the cell-specific Koffset.

[0097] As an example, we will explain the case where RO#3, which corresponds to SSB3, is configured for terminal 200.

[0098] For example, in Case 1 of Figure 10, RO#1 (e.g., the first RO) corresponding to SSB1 of frame n is set after the timing specified by Koffset, so terminal 200 sends PRACH at RO#3 of frame n.

[0099] On the other hand, in Case 2 of Figure 10, RO#1 corresponding to SSB1 of frame n (for example, the first RO) is set before the timing specified by Koffset, and RO#1 corresponding to SSB1 of frame n+1 (for example, the first RO) is set after the timing specified by Koffset. Therefore, terminal 200 does not send PRACH in RO#3 of frame n, but sends PRACH in RO#3 of frame n+1, where RO#1 corresponding to SSB1 is set after the timing specified by Koffset.

[0100] Thus, in decision method 2, terminal 200 selects an RO (RO#3 in frame n+1 in case 2 of Figure 10) that is included in an earlier set of ROs from among the sets of ROs that are later than the timing based on the cell-specific Koffset (for example, the set including RO#1 to RO#4 in Figure 10). As a result, terminal 200 controls PRACH transmission on a unit of the same set of ROs (RO#1 to RO#4 in Figure 10), regardless of the timing relationship between the timing specified by the cell-specific Koffset and the RO, making PRACH timing management easier.

[0101] The above describes an example of how to determine the timing of PRACH transmission based on the cell-specific Koffset.

[0102] Thus, in this embodiment, terminal 200 determines the RO of a PRACH transmission using either a cell-specific Koffset or a terminal-specific Koffset (e.g., a parameter different from the cell-specific offset) based on a control signal related to uplink transmission (e.g., PDCCH). For example, terminal 200 may determine the RO using the cell-specific Koffset when triggered to transmit a PRACH by a PDCCH. Similarly, base station 100 may determine the RO of a PRACH transmission using the cell-specific Koffset without using the terminal-specific Koffset when triggered to transmit a PRACH by a PDCCH.

[0103] By using a cell-specific Koffset, the RO for PRACH transmission is determined regardless of the terminal 200's location, thus suppressing timing discrepancies in PRACH transmission between the base station 100 and the terminal 200. For example, any terminal 200 located within the base station 100's cell can transmit PRACH at a timing based on the cell-specific Koffset.

[0104] Furthermore, even if, for example, the terminal 200 is located further from the satellite than the location assumed by the base station 100, the terminal 200 can avoid cases where it is unable to transmit PRACH at the RO specified by the base station 100 in time, and can reliably transmit PRACH.

[0105] Furthermore, in this embodiment, for example, the base station 100 identifies the timing (e.g., RACH slot or RO) when the terminal 200 transmits PRACH, so the base station 100 does not need to perform blind reception of PRACH, and the processing of the base station 100 can be simplified.

[0106] Therefore, according to this embodiment, appropriate timing control can be achieved in accordance with the propagation delay between the base station 100 and the terminal 200.

[0107] In this embodiment, as an example, a case in which the cell-specific Koffset and the terminal-specific Koffset are notified to the terminal 200 has been described, but the embodiment is not limited to this. For example, the cell-specific Koffset may be notified to the terminal 200, and further, the difference (e.g., "ΔK") to the cell-specific Koffset may also be notified to the terminal 200. In this case, the terminal-specific Koffset may be set to cell-specific Koffset + ΔK. In addition, the notification of the timing offset to the terminal 200 may be made by, for example, at least one of RRC signaling, MAC CE, and DCI.

[0108] Furthermore, if terminal 200 is triggered to send a PRACH by PDCCH (i.e., when it receives a DCI for order RACH), its synchronization state is considered uncertain. Therefore, it may discard its terminal-specific Koffset and use the cell-specific Koffset for subsequent communications, including PRACH transmissions (even if b, PDSCH reception, PUSCH transmission, or PUCCH transmission, etc.), until a new terminal-specific Koffset is set.

[0109] (Embodiment 2) The configuration of the base station and terminal according to this embodiment may be the same as the configuration of the base station 100 and terminal 200 shown in Embodiment 1.

[0110] In this embodiment, when a PRACH transmission is triggered by a PDCCH, for example, the base station 100 and terminal 200 control the transmission timing and reception timing of the PRACH based on information regarding the opportunity to transmit the PRACH (e.g., RO).

[0111] For example, the base station 100 may notify the terminal 200 of information regarding the RO used for PRACH transmission by means of DCI that triggers RACH (for example, PDCCH for RACH trigger). When the terminal 200 receives DCI that triggers RACH, for example, it may determine the RO based on the information regarding the RO included in the DCI and transmit PRACH in the determined RO.

[0112] The information regarding the RO (hereinafter referred to as "RO information") may include information indicating the use of either one of, for example, a cell-specific offset and a parameter different from the cell-specific offset (for example, terminal-specific Koffset described later, or "the next available RO").

[0113] Examples of RO information will be described below.

[0114] <Example 1 of RO information> The RO information may notify, for example, the type of Koffset used for determining the RO. For example, the RO information may include information indicating the use of either one of a cell-specific Koffset and a terminal-specific Koffset (for example, an example of a parameter different from the cell-specific Koffset).

[0115] The base station 100 may notify RO information indicating the use of terminal-specific Koffset to the terminal 200 that has identified its synchronization state or location, for example. On the other hand, the base station 100 may notify RO information indicating the use of cell-specific Koffset to the terminal 200 that has not identified its synchronization state or location, or the terminal 200 whose synchronization state or location is uncertain, for example.

[0116] Thus, for the terminal 200 whose synchronization state (or position) is identified by the base station 100, appropriate timing control for the terminal 200 can be performed by setting the timing of PRACH transmission based on the terminal-specific Koffset, so that the delay of PRACH transmission can be reduced. Also, for the terminal 200 whose synchronization state (or position) is unknown or uncertain in the base station 100, by setting the timing of PRACH transmission based on the cell-specific Koffset, an RO that the terminal 200 can surely transmit can be specified regardless of the state of the terminal 200 within the cell.

[0117] <Example 2 of RO information> The RO information may include, for example, information indicating the use of either the cell-specific Koffset or the RO available to the terminal 200 (e.g., "the next available RO") (e.g., an example of a parameter different from the cell-specific Koffset) regarding the determination of the RO.

[0118] The base station 100 may notify, for example, the terminal 200 whose synchronization state or position is identified, of the RO information instructing the use of "the next available RO". On the other hand, the base station 100 may notify, for example, the terminal 200 whose synchronization state or position is not identified or the terminal 200 whose synchronization state or position is uncertain, of the RO information instructing the use of the cell-specific Koffset.

[0119] Thus, the terminal 200 whose synchronization state (or position) is identified by the base station 100 can transmit PRACH at an earlier timing by setting "the next available RO", so that the delay of PRACH transmission can be reduced. Also, for the terminal 200 whose synchronization state (or position) is unknown or uncertain in the base station 100, by setting the timing of PRACH transmission based on the cell-specific Koffset, an RO that the terminal 200 can surely transmit can be specified regardless of the state of the terminal 200 within the cell.

[0120] The above has described an example of the RO information.

[0121] Note that the RO information may be set as follows.

[0122] For example, base station 100 may notify terminal 200, whose synchronization status or location is known, of the use of non-contention-based RACH (e.g., at least one of the SSB number and preamble number) and terminal-specific Koffset via RO information.

[0123] On the other hand, the base station 100 may, for example, notify a terminal 200 that does not specify its synchronization status or location, or a terminal 200 whose synchronization status or location is uncertain, of the use of contention-based RACH and the "next available RO" by RO information. In notifying of contention-based RACH, for example, the base station 100 does not need to notify the SSB number and preamble number. Furthermore, not notifying the SSB number and preamble number can be achieved, for example, by notifying the Random Access Preamble index or ra-PreambleIndex=0.

[0124] Furthermore, the base station 100 may notify the terminal 200 of RO information instructing it to use, for example, a cell-specific Koffset, a terminal-specific Koffset, or "the next available RO."

[0125] Next, I will explain how RO information is notified.

[0126] <Notification method 1> In NR Rel.15, the DCI that indicates PDCCH order RACH uses, for example, DCI format 1_0 used for scheduling PDSCH. The number of bits used in the DCI that indicates PDCCH order RACH is less than the number of bits used for scheduling PDSCH. Therefore, DCI format 1_0 that indicates PDCCH order RACH may have more reserved bits set compared to when scheduling PDSCH.

[0127] Therefore, in notification method 1, RO information may be notified using, for example, a portion of the reserved bits of DCI format 1_0 that indicate PDCCH order RACH.

[0128] In notification method 1, RO information is notified as individual bits, which increases the flexibility of settings at base station 100. Furthermore, since RO information is notified using a portion of the reserved bits of DCI format 1_0, the increase in the total number of bits in DCI can be suppressed.

[0129] Furthermore, RO information is not limited to DCI format 1_0; it may also be communicated through other existing channels or control information (e.g., reserved bit).

[0130] <Notification method 2> NR Rel.15 specifies that DCIs that instruct PDCCH order RACH will be notified of either contention-based RACH or non-contention-based RACH.

[0131] For example, if the Random Access Preamble index (or ra-PreambleIndex) is 0 (all zeros, e.g., 0b000000), it corresponds to contention-based RACH, and terminal 200 randomly selects a preamble sequence from the ROs corresponding to the SSB selected by terminal 200 and sends PRACH.

[0132] On the other hand, when the Random Access Preamble index (or ra-PreambleIndex) is not 0 (all zeros; e.g., 0b000000), it corresponds to non-contention based RACH. The terminal 200 transmits a PRACH using a preamble sequence of the preamble number specified by the Random Access Preamble index in the RO specified by the PRACH Mask index among the ROs corresponding to the SSB specified by the SS / PBCH index.

[0133] In notification method 2, the base station 100 may implicitly notify the terminal 200 of the RO information according to, for example, whether it is contention based RACH or non-contention based RACH. For example, the base station 100 and the terminal 200 may determine the RO information according to whether the Random Access Preamble index is 0 (all zeros; e.g., 0b000000).

[0134] As an example, in the case of <Example 1 of RO information> described above, the terminal 200 may determine the RO using the cell-specific Koffset when the Random Access Preamble index is 0 (e.g., in the case of contention based RACH), and may determine the RO using the terminal-specific Koffset when the Random Access Preamble index is not 0 (e.g., in the case of non-contention based RACH).

[0135] In other words, the RO information may include either information associated with the cell-specific Koffset (e.g., information indicating contention based RACH) or information associated with the terminal-specific Koffset (e.g., information indicating non-contention based RACH).

[0136] For example, for the terminal 200 whose synchronization state or location is identified, the base station 100 may set the Random Access Preamble index to a value different from 0 and notify the terminal 200 of the SSB, RO, and preamble number. At this time, since the base station 100 identifies that the terminal 200 can transmit PRACH at the timing based on the terminal-specific Koffset set for the terminal 200, for example, the timing of the RO may be determined by the terminal-specific Koffset. Also, for example, since the Random Access Preamble index of the terminal 200 is a value different from 0, the terminal 200 may identify that the use of the terminal-specific Koffset is implicitly notified.

[0137] On the other hand, for example, for the terminal 200 whose synchronization state or location is not identified or whose synchronization state or location is uncertain, the base station 100 may set the Random Access Preamble index to 0 and trigger contention based RACH for the terminal 200. At this time, since the base station 100 does not identify whether the terminal 200 can transmit PRACH at the timing based on the terminal-specific Koffset set for the terminal 200, for example, the timing of the RO may be determined by the cell-specific Koffset. Also, for example, since the Random Access Preamble index of the terminal 200 is 0, the terminal 200 may identify that the use of the cell-specific Koffset is implicitly notified.

[0138] As another example, in the case of <Example 2 of RO information> described above, for example, when the Random Access Preamble index of the terminal 200 is 0 (for example, in the case of contention based RACH), the terminal 200 may determine the RO using the cell-specific Koffset, and when the Random Access Preamble index is not 0 (for example, in the case of non-contention based RACH), the terminal 200 may determine the RO using the "next available RO".

[0139] In other words, RO information may include either information associated with a cell-specific Koffset (e.g., information indicating a contention-based RACH) or information associated with the "next available RO" (e.g., information indicating a non-contention-based RACH).

[0140] For example, the base station 100 may set the Random Access Preamble index to a value other than 0 for a terminal 200 whose synchronization status or location is known, and notify the terminal 200 of the SSB, RO, and preamble number as non-contention based RACH. In this case, the base station 100 may determine the timing of the RO based on the "next available RO" because it has determined that the terminal 200 is able to transmit PRACH based on the timing based on the "next available RO". Also, the terminal 200 may determine that it has been implicitly notified that the "next available RO" is available because the Random Access Preamble index is a value other than 0.

[0141] On the other hand, the base station 100 may, for example, set the Random Access Preamble index to 0 for a terminal 200 whose synchronization state or location is not specified, or for a terminal 200 whose synchronization state or location is uncertain, and trigger a contention-based RACH for the terminal 200. In this case, since the base station 100 does not specify the "next available RO" for the terminal 200, it may determine the timing of the RO using the cell-specific Koffset. Also, since the terminal 200 has a Random Access Preamble index of 0, it may implicitly recognize that it has been notified to use the cell-specific Koffset.

[0142] In non-contention based RACH, the base station 100 can reduce the transmission delay of the PRACH by designating an RO based on the "next available RO" to the terminal 200 in order to receive the PRACH with the SSB and preamble number designated for the terminal 200. Also, since the base station 100 can assume the reception of the PRACH with the SSB and preamble number designated for the terminal 200, blind decoding at the base station 100 can be suppressed.

[0143] Also, in contention based RACH, the base station 100 notifies the terminal 200 that instructs the PDCCH order RACH to use the cell-specific Koffset and waits for the PRACH transmitted from the terminal 200 that is not an initial access. Since the PRACH reception timing at the base station 100 is known, blind decoding can be suppressed.

[0144] Also, as another example, in the case of <Example 2 of RO information> described above, the terminal 200 may determine the RO using the "next available RO" when, for example, the Random Access Preamble index is 0 (for example, in the case of contention based RACH), and may determine the RO using the terminal-specific Koffset when the Random Access Preamble index is not 0 (for example, in the case of non-contention based RACH).

[0145] In other words, the RO information may include either information associated with the "next available RO" (for example, information instructing contention based RACH) or information associated with the terminal-specific Koffset (for example, information instructing non-contention based RACH).

[0146] For example, the base station 100 may set the Random Access Preamble index to a value other than 0 for a terminal 200 whose synchronization status or location is known, and notify the terminal 200 of the SSB, RO, and preamble number as non-contention based RACH. In this case, the base station 100 may determine the timing of the RO by the terminal-specific Koffset, for example, because it has determined that the terminal 200 is capable of transmitting PRACH based on the timing based on the terminal-specific Koffset. Furthermore, the terminal 200 may determine that the use of the terminal-specific Koffset has been implicitly notified, for example, because the Random Access Preamble index is a value other than 0.

[0147] On the other hand, the base station 100 may, for example, set the Random Access Preamble index to 0 for a terminal 200 whose synchronization state or location is not specified, or for a terminal 200 whose synchronization state or location is uncertain, and trigger a contention-based RACH for the terminal 200. In this case, the base station 100 may, for example, determine the timing of the RO based on the terminal 200's "next available RO". Also, the terminal 200 may, for example, determine that it has been implicitly notified that it will use the "next available RO" because the Random Access Preamble index is 0.

[0148] In non-contention-based RACH, base station 100 receives PRACH for the SSB and preamble number specified to terminal 200. By specifying an RO based on the terminal-specific Koffset to terminal 200, the transmission delay of PRACH can be reduced. Furthermore, since base station 100 can anticipate receiving PRACH for the SSB and preamble number specified to terminal 200, blind decoding at base station 100 can be suppressed.

[0149] Furthermore, in Contention-based RACH, for example, terminal 200 may use PRACH resources that compete with the terminal with initial access. Therefore, base station 100 performs blind decoding for terminal 200 with initial access. For this reason, base station 100 also notifies terminal 200, which instructs PDCCH order RACH, of the use of the "next available RO" and waits for PRACH transmitted from terminal 200 that is not with initial access. Base station 100 performs blind decoding because the RO, SSB, and Preamble number selected by terminal 200 are unknown. Since base station 100 performs blind decoding similar to that of PRACH transmitted from terminal 200 with initial access, no additional complex processing is required. On the other hand, terminal 200 behaves similarly to terminal 200 with initial access, thus simplifying terminal 200's operation.

[0150] In notification method 2, RO-related information is implicitly notified to terminal 200, thus suppressing an increase in the amount of information in RO information notification. Furthermore, for example, by implicitly notifying terminal 200 of RO information based on the value of the Random Access Preamble index, appropriate notification of the RACH type (e.g., either contention-based RACH or non-contention-based RACH) and RO timing is possible depending on the status of terminal 200 as understood by base station 100.

[0151] The above explains examples of methods for notifying RO information.

[0152] Thus, in this embodiment, terminal 200 determines the RO for PRACH transmission using either a cell-specific Koffset or a parameter different from the cell-specific Koffset (e.g., terminal-specific Koffset or "next available RO") based on a control signal related to uplink transmission (e.g., RO information). Similarly, base station 100 determines the RO for PRACH reception using either a cell-specific Koffset or a parameter different from the cell-specific Koffset (e.g., terminal-specific Koffset or "next available RO") based on a control signal related to uplink reception (e.g., RO information).

[0153] By notifying the base station 100 of information regarding RO, the base station 100 can appropriately control the PRACH transmission timing, for example, according to the recognition status of the terminal 200. Therefore, according to this embodiment, appropriate timing control can be achieved in accordance with the propagation delay between the base station 100 and the terminal 200.

[0154] In this embodiment, an example was described in which information regarding the RO used for PRACH transmission is notified to terminal 200 by a DCI that triggers RACH (e.g., PDCCH for RACH trigger). However, information regarding the RO is not limited to DCI; it may also be notified (or set) to terminal 200 by other signals (e.g., SIB, RRC signaling, MAC CE). Furthermore, the method of notifying RO information is not limited to the above; for example, information regarding the RO may be notified by bits added to DCI.

[0155] Furthermore, if terminal 200 is triggered to send a PRACH by PDCCH (i.e., receives a DCI for PDCCH order RACH) and sends a PRACH with an RO determined based on the cell-specific Koffset, the synchronization state is considered uncertain. Therefore, terminal 200 may discard its held terminal-specific Koffset and use the cell-specific Koffset for subsequent communications (e.g., PDSCH reception, PUSCH transmission, or PUCCH transmission) until a new terminal-specific Koffset is set. Also, if terminal 200 sends a PRACH with an RO determined based on a parameter different from the cell-specific Koffset (e.g., terminal-specific Koffset or "next available RO"), the synchronization state is considered to be maintained. Therefore, terminal 200 may use its held terminal-specific Koffset for subsequent communications (e.g., PDSCH reception, PUSCH transmission, or PUCCH transmission).

[0156] (Embodiment 3) The configuration of the terminal and base station according to this embodiment may be the same as the configuration of the base station 100 and terminal 200 shown in Embodiment 1.

[0157] In this embodiment, for example, a method for determining the RO used in PDCCH order RACH based on an offset different from the Koffset (e.g., cell-specific Koffset and terminal-specific Koffset) is described.

[0158] Offset information may be notified to terminal 200, for example, by RRC signaling, or it may be notified to terminal 200 by being included in PDCCH that triggers RACH.

[0159] The method for setting the offset according to this embodiment will be described below.

[0160] <Setup Method 1> In configuration method 1, the offset refers to the number of slots from the transmit slot of the PDCCH that triggers RACH (e.g., PDCCH for RACH trigger). In other words, the offset in configuration method 1 is an offset in units of slots.

[0161] For example, if the offset value is N, terminal 200 may transmit PRACH in the RO corresponding to the timing of the slot N slots after the slot in which base station 100 transmitted PDCCH.

[0162] Furthermore, terminal 200 may, for example, send a PRACH at the RO corresponding to the notified SSB if the SSB and preamble number are notified by base station 100, or send a PRACH at the RO corresponding to the SSB selected by terminal 200 if the SSB and preamble number are not notified by base station 100.

[0163] <Setup Method 2> In configuration method 2, the offset refers to the number of RACH slots from the transmit slot of the PDCCH that triggers RACH (e.g., PDCCH for RACH trigger). In other words, the offset in configuration method 2 is an offset per RACH slot, including the RO (transmit opportunity) of the PRACH.

[0164] For example, if the offset value is N, terminal 200 may send a PRACH in the RO (or an RO after the RO in the Nth RACH slot) of the Nth RACH slot set in the corresponding cell, after the slot from which base station 100 sent a PDCCH. Note that the RACH slot set in the cell may be notified, for example, by the RRC parameter RACH-ConfigCommon.

[0165] Figure 11 shows an example of setting RO in setting method 2. Figure 11 shows an example where N=3. As shown in Figure 11, terminal 200 may send PRACH in the RO (for example, any of RO#1 to RO#4) in the third RACH slot after the slot in which base station 100 sent PDCCH for RACH trigger.

[0166] Furthermore, if the SSB, RO, and preamble numbers are notified by the base station 100, the terminal 200 may transmit a PRACH at the designated RO of the notified SSB. Also, if the SSB, RO, and preamble numbers are notified by the base station 100, the terminal 200 may randomly select an RO and preamble corresponding to the SSB selected by the terminal 200 and transmit a PRACH.

[0167] In configuration method 2, the offset is notified on a per-RACH slot basis. For example, compared to configuration method 1 (notification on a per-slot basis), the number of bits used to represent the offset can be reduced, thus reducing the amount of offset signaling.

[0168] <Setup Method 3> In configuration method 3, the offset refers to, for example, the number of ROs (transmit opportunities) from the transmit slot of the PDCCH that triggers RACH (e.g., PDCCH for RACH trigger). In other words, the offset in configuration method 3 is the offset per RO (transmit opportunity) of PRACH.

[0169] For example, if the offset value is N, terminal 200 may send PRACH at the Nth RO (or ROs from the Nth RO onward) among the ROs set in the corresponding cell, starting from the slot where base station 100 sent PDCCH. Note that the ROs set in the cell may be notified, for example, by the RRC parameter RACH-ConfigCommon.

[0170] Figure 12 shows an example of RO configuration in configuration method 3. Figure 12 shows an example where N=9. As shown in Figure 12, terminal 200 may transmit PRACH in the 9th RO (e.g., RO#1) after the slot in which base station 100 transmitted PDCCH for RACH trigger.

[0171] As shown in Figure 12, when ROs are frequency-division multiplexed (FDM), multiple ROs at the same timing (e.g., the same slot) may be counted in descending order of frequency. However, the method of counting ROs is not limited to ascending order of frequency; for example, they may be counted in descending order of frequency, or in a predetermined order independent of frequency.

[0172] Furthermore, if the SSB, RO, and preamble numbers are notified by the base station, terminal 200 may transmit a PRACH at the designated RO of the notified SSB. Also, if the SSB, RO, and preamble numbers are notified by the base station 100, terminal 200 may randomly select an RO and preamble corresponding to the SSB selected by terminal 200 and transmit a PRACH.

[0173] In configuration method 3, the RO unit offset is notified, so compared to configuration method 1 (slot unit notification), for example, the number of bits used to represent the offset can be reduced, and the amount of offset signaling can be reduced. Also, in configuration method 3, for example, even when ROs are frequency multiplexed, the base station 100 can appropriately specify an RO from among the frequency multiplexed ROs to the terminal 200.

[0174] <Setup Method 4> In setting method 4, the offset refers to, for example, the offset from the cell-specific Koffset or the terminal-specific Koffset. For example, terminal 200 may send PRACH in the ROs from the cell-specific Koffset or terminal-specific Koffset onward, plus the number of slots indicated by the notified offset. Note that the offset can be zero or a negative value.

[0175] Figure 13 shows an example where an offset from the cell-specific Koffset (e.g., Offset for RACH) is notified. Terminal 200 may send PRACH in ROs (e.g., ROs from Frame #n+1 onwards) that are shifted by the RACH offset notified in the cell-specific Koffset from the slot where base station 100 sent a PDCCH that triggers RACH (e.g., PDCCH for RACH trigger).

[0176] The base station 100 may specify an offset that takes into account the time required for at least one of the terminal 200's PDCCH reception, decoding, and PRACH signal generation processes. Specifying an offset prevents, for example, cases where the terminal 200's processing cannot keep up with the specified PRACH transmission timing, ensuring that the terminal 200 reliably transmits the PRACH. Furthermore, by notifying the offset as an offset from the cell-specific Koffset or terminal-specific Koffset, the number of notification bits can be reduced and control overhead can be reduced compared to setting an offset from the PDCCH transmission slot.

[0177] The base station 100 may also notify the terminal 200 of a selection of offset candidates, such as a parameter used for time resource allocation in PUSCH (e.g., K2 in PUSCH-TimeDomainResourceAllocationList) or a parameter used to control the HARQ-ACK transmission timing (e.g., dl-DataToUL-ACK in PUSCH-Config). For example, the range defined in the 3GPP specification (e.g., TS38.331) may be used as an offset candidate, or one or more values ​​set by the base station 100 for the terminal 200 may be used as an offset candidate. This limits the possible values ​​for the offset, thereby further reducing the number of notification bits.

[0178] Alternatively, base station 100 may select as the offset a value from, for example, a parameter used for time resource allocation of PUSCH (e.g., K2 in PUSCH-TimeDomainResourceAllocationList) or a parameter for controlling the HARQ-ACK transmission timing (e.g., dl-DataToUL-ACK in PUCCH-Config). The selected value may be, for example, the minimum, median, maximum, or first (or last) value from the values ​​defined in the 3GPP specification (e.g., TS38.331), or the minimum, median, maximum, or first (or last) value from one or more values ​​set by base station 100 to terminal 200. In this case, base station 100 does not need to separately notify terminal 200 of the offset, as terminal 200 can obtain the offset for PDCCH order RACH from these set parameters.

[0179] The above explains an example of how to set an offset.

[0180] In this embodiment, when the base station 100 triggers a PDCCH order RACH to the terminal 200, it specifies the PRACH transmission timing based on offsets different from the cell-specific Koffset and the terminal-specific Koffset. This allows the base station 100 and the terminal 200 to determine the timing of the PDCCH order RACH regardless of the status of the terminal 200 (e.g., synchronization state or location), thereby suppressing discrepancies in the recognition of the PRACH transmission timing between the base station 100 and the terminal 200. Furthermore, since the base station 100 can determine the PRACH transmission timing based on the offset, it does not need to perform blind decoding of the PRACH, thus simplifying the processing of the base station 100.

[0181] Furthermore, for example, by the base station 100 appropriately setting an offset for each terminal 200, it is possible to avoid cases where the terminal 200's processing cannot keep up with the PRACH transmission timing instructed by the base station 100, and the terminal 200 can reliably transmit PRACH.

[0182] Furthermore, if terminal 200 is triggered to send a PRACH by PDCCH (i.e., receives a DCI for order RACH), its synchronization state is considered uncertain. Therefore, it may discard its terminal-specific Koffset and use the cell-specific Koffset for subsequent communications, including PRACH transmissions (e.g., PDSCH reception, PUSCH transmission, or PUCCH transmission), until a new terminal-specific Koffset is set.

[0183] The embodiments of this disclosure have been described above.

[0184] In Embodiment 1, the PRACH transmission timing determination methods 1 and 2 described were examples using a cell-specific Koffset, but the method is not limited to this. Determination methods 1 and 2 may also be applied when a terminal-specific Koffset is used, for example, as in Embodiment 2 or 3.

[0185] Furthermore, while the above embodiments describe a case in which the trigger for RACH from the base station 100 is notified to the terminal 200 by PDCCH (or DCI), the invention is not limited to this. For example, the trigger for RACH may be notified to the terminal 200 by other information such as RRC information or MAC CE. For example, information regarding the Koffset used to determine the RO during handover, and information regarding the RO, may be notified (or set) to the terminal 200 by RRC parameters (or RRC information), and the terminal 200 may determine the RO when transmitting RACH to the handover cell based on the notified information.

[0186] Furthermore, each timing in the above embodiments may be defined by the transmission timing of the base station 100. For example, when terminal 200 transmits an uplink signal such as PRACH in "slot k, N slots after the PDCCH transmission slot", terminal 200 may transmit PRACH after performing timing advance so that it is received at slot k by base station 100. Note that each timing in the above embodiments is not limited to the transmission timing of base station 100, but may also be defined by the transmission or reception timing of other devices (for example, terminal 200).

[0187] In each of the above embodiments, when the RO is determined by a terminal-specific Koffset, a cell-specific Koffset, or a separately notified offset different from the Koffset, if the processing of terminal 200 does not meet the timing specified by base station 100, terminal 200 may transmit a PRACH at or after the RO following the specified RO. An example of a case where the processing of terminal 200 does not meet the specified timing is when a timing earlier than the next available RO is specified. Furthermore, if the processing of terminal 200 does not meet the specified timing, terminal 200 may, for example, determine that some recognition discrepancy has occurred between it and base station 100 and transmit a contention-based RACH at any time to prompt RRC reset, or initiate a Radio Link Failure (RLF) procedure. This enables rapid recovery of the recognition discrepancy.

[0188] Furthermore, in each of the above embodiments, the cell-specific Koffset and terminal-specific Koffset may be used not only for the transmission timing of PRACH, but also for other timings such as the transmission timing of HARQ-ACK to PDSCH, the transmission timing of PUSCH to PDCCH that schedules PUSCH, the reference timing for quality measurement when reporting CSI, or the timing of MAC CE reflection. In addition, any offset value that corrects delay can be used as a substitute for Koffset. For example, the RTT estimated at terminal 200 (or the delay time based on the round-trip time between base station 100 and terminal 200) may be used instead of Koffset.

[0189] Furthermore, in each of the above embodiments, the cell-specific Koffset may be replaced with a beam-specific Koffset.

[0190] Furthermore, each of the above embodiments may be applied to RACH transmissions instructed by RRC signaling, such as RACH transmissions during handover. In this case, the timing that serves as the basis for the offset may be, for example, the timing at which the RRC message that triggers the RACH transmission is sent, or it may be notified separately. Moreover, each of the above embodiments is not limited to handover, but can be applied to other applications as well, when notifying the timing of RACH transmissions.

[0191] Furthermore, in each of the above embodiments, the slot length varies, for example, depending on the subcarrier spacing (SCS). Also, for example, the SCS of PRACH may differ from the SCS of other channels (e.g., PDSCH or PUSCH). For example, if the SCS of PRACH differs from the SCS of other channels, the SCS used for counting the number of slots (for example, called the "reference SCS") may be set to 15kHz in FR1 (frequency region 1) and to 60kHz in FR2 (frequency region 2), similar to Rel.15. In addition, the Koffset or offset in each of the above embodiments may be normalized based on the following equation (1).

number

[0192] Furthermore, the various parameters in each of the above embodiments are merely examples, and other values ​​may be used. For example, the number of SSB types is not limited to the four types shown in Figures 10, 11, and 12, but may be any other number. Also, the number of ROs is not limited to the four or eight types shown in Figures 10, 11, and 12, but may be any other number. In addition, the number of ROs included in each RACH slot is not limited to the two or four shown in Figures 10, 11, and 12, but may be any other number.

[0193] Furthermore, while we have described an example where RO is determined based on a timing delay of the Koffset slot from the PDCCH transmission slot that triggers RACH, an additional offset may be added to consider, for example, terminal processing delays.

[0194] Furthermore, in the embodiments described above, the use of "next available RO" was explained as an example of RO setting. However, the available RO is not limited to cases where "next available RO" is set; for example, any of the ROs available in subsequent times may be set.

[0195] Furthermore, although the embodiments described above were explained using an NTN environment (e.g., a satellite communication environment) as an example, this disclosure is not limited thereto. This disclosure may also be applied to other communication environments (e.g., at least one terrestrial cellular environment of LTE and NR).

[0196] Furthermore, while the embodiments described above include examples of using GNSS such as GPS (for example, position detection using satellite signals), position detection may also be performed using ground cellular base stations, at least one of WiFi signals and Bluetooth® signals, accelerometers, or a combination thereof. In addition to latitude and longitude, the position information may also include altitude information. Alternatively, it may be a value of a separately defined coordinate system. Altitude information may be obtained from a barometric pressure sensor or the like.

[0197] Furthermore, in each of the embodiments described above, the signals and information broadcast from the base station 100 may be transmitted by at least one of SSB and SIB, or by a method that can be received by multiple terminals, for example, by a group-common DCI format (DCI format 2_x, etc.).

[0198] Furthermore, in each of the embodiments described above, the cell may be an area defined by the received power of at least one of the SSB and CSI-RS transmitted by the base station (or satellite), or it may be an area defined by its geographical location. Also, the cell in the above embodiments may be replaced by the beam defined by the SSB.

[0199] A base station may be referred to as a gNodeB or gNB. A terminal may be referred to as a UE.

[0200] Slots may be replaced with time slots, mini-slots, frames, subframes, etc.

[0201] Furthermore, in each of the embodiments described above, the form of satellite communication may be a configuration in which the base station functions reside on the satellite (e.g., "regenerative satellite"), or a configuration in which the base station functions reside on the ground and the satellite relays communication between the base station and the terminal (e.g., "transparent satellite"). In other words, for example, in one embodiment of this disclosure, the downlink and uplink may be links between the terminal and the satellite, or links via the satellite.

[0202] Furthermore, one embodiment of this disclosure can be applied regardless of the type of satellite, such as GEO, MEO (Medium Earth Orbit satellite), LEO (Low Earth Orbit satellite), or HEO (Highly Elliptical Orbit satellite). Also, one embodiment of this disclosure may be applied to non-terrestrial communications, such as HAPS (High Aerospace Platforms) or drone base stations.

[0203] Furthermore, in each of the embodiments described above, the radio wave propagation speed is set to approximately 3 × 10⁻⁶. 8 Although it is written as [m / s], it is not limited to this; for example, 2.99792××10 8 Numerical values ​​such as [m / s] may be used. The accuracy of the radio wave propagation speed may depend on the implementation.

[0204] Although the embodiments described above explained four-step random access, the random access procedure is not limited to this, and for example, two-step random access may also be used.

[0205] Furthermore, the notation "...part" in each of the embodiments described above may be replaced with other notations such as "...circuitry," "...device," "...unit," or "...module."

[0206] (supplement) Information indicating whether the terminal 200 supports the functions, operations, or processes described in each of the embodiments described above may be transmitted (or notified) from the terminal 200 to the base station 100, for example, as capability information or capability parameters of the terminal 200.

[0207] The capability information may include an information element (IE) that individually indicates whether the terminal 200 supports at least one of the functions, operations, or processes shown in each of the embodiments described above. Alternatively, the capability information may include an information element that indicates whether the terminal 200 supports any two or more combinations of the functions, operations, or processes shown in each of the embodiments described above.

[0208] The base station 100 may, for example, determine (or decide or assume) which functions, operations, or processes the source terminal 200 supports (or does not support) based on capability information received from the terminal 200. The base station 100 may perform operations, processes, or controls in accordance with the determination result based on the capability information. For example, the base station 100 may control the allocation (in other words, scheduling) of at least one downlink resource such as PDCCH or PDSCH, and an uplink resource such as PUCCH or PUSCH, based on capability information received from the terminal 200.

[0209] Furthermore, the fact that terminal 200 does not support some of the functions, operations, or processes shown in each of the embodiments described above may be interpreted as the terminal 200 having restrictions on such some functions, operations, or processes. For example, information or requests regarding such restrictions may be notified to base station 100.

[0210] Information regarding the capabilities or limitations of terminal 200 may, for example, be defined in a standard, or it may be implicitly communicated to base station 100 in association with information known at base station 100 or information transmitted to base station 100.

[0211] (Control signal) In this disclosure, the downlink control signal (or downlink control information) related to one embodiment of this disclosure may be, for example, a signal (or information) transmitted in a Physical Downlink Control Channel (PDCCH) at the physical layer, or a signal (or information) transmitted in a Medium Access Control Control Element (MAC CE) or Radio Resource Control (RRC) at a higher layer. Furthermore, the signal (or information) is not limited to being notified by the downlink control signal, but may be predetermined in a specification (or standard), or may be pre-configured in the base station and terminal.

[0212] In this disclosure, the uplink control signal (or uplink control information) related to one embodiment of this disclosure may be, for example, a signal (or information) transmitted in the physical layer PUCCH, or a signal (or information) transmitted in the upper layer MAC CE or RRC. Furthermore, the signal (or information) is not limited to being notified by the uplink control signal, but may be predetermined in the specification (or standard), or may be pre-configured in the base station and terminal. In addition, the uplink control signal may be replaced with, for example, uplink control information (UCI), 1st stage sidelink control information (SCI), or 2nd stage SCI.

[0213] (base station) In one embodiment of this disclosure, the base station may be a Transmission Reception Point (TRP), cluster head, access point, Remote Radio Head (RRH), eNodeB (eNB), gNodeB (gNB), Base Station (BS), Base Transceiver Station (BTS), master unit, gateway, etc. In side-link communication, the terminal may also assume the role of a base station. Alternatively, instead of a base station, a relay device that relays communication between a higher-level node and a terminal may be used. It may also be a roadside unit.

[0214] (Uphill rink / Downhill rink / Side rink) One embodiment of the present disclosure may be applied to, for example, an uplink, a downlink, or a sidelink. For example, one embodiment of the present disclosure may be applied to the Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH), Physical Random Access Channel (PRACH) of an uplink, the Physical Downlink Shared Channel (PDSCH), PDCCH, Physical Broadcast Channel (PBCH) of a downlink, or the Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Control Channel (PSCCH), Physical Sidelink Broadcast Channel (PSBCH) of a sidelink.

[0215] PDCCH, PDSCH, PUSCH, and PUCCH are examples of downlink control channels, downlink data channels, uplink data channels, and uplink control channels, respectively. PSCCH and PSSCH are examples of sidelink control channels and sidelink data channels. PBCH and PSBCH are examples of broadcast channels, and PRACH is an example of a random access channel.

[0216] (Data channel / Control channel) One embodiment of the present disclosure may be applied to either a data channel or a control channel, for example. For example, the channel in one embodiment of the present disclosure may be replaced with any of the data channels PDSCH, PUSCH, PSSCH, or the control channels PDCCH, PUCCH, PBCH, PSCCH, PSBCH.

[0217] (reference signal) In one embodiment of the present disclosure, the reference signal is, for example, a signal known to both the base station and the mobile station, and may be called a Reference Signal (RS) or pilot signal. The reference signal may be any of the following: Demodulation Reference Signal (DMRS), Channel State Information - Reference Signal (CSI-RS), Tracking Reference Signal (TRS), Phase Tracking Reference Signal (PTRS), Cell-specific Reference Signal (CRS), or Sounding Reference Signal (SRS).

[0218] (Time interval) In one embodiment of the present disclosure, the unit of time resource is not limited to one or a combination of slots and symbols, but may also be a time resource unit such as a frame, superframe, subframe, slot, time slot subslot, minislot, or symbol, Orthogonal Frequency Division Multiplexing (OFDM) symbol, Single Carrier - Frequency Division Multiplexing (SC-FDMA) symbol, or any other time resource unit. Furthermore, the number of symbols contained in one slot is not limited to the number of symbols exemplified in the above embodiment, but may be any other number of symbols.

[0219] (Frequency band) One embodiment of this disclosure may be applied to either a licensed band or an unlicensed band.

[0220] (communication) One embodiment of the present disclosure may be applied to communication between a base station and a terminal (Uu-link communication), communication between terminals (Sidelink communication), or Vehicle to Everything (V2X) communication. For example, the channel in one embodiment of the present disclosure may be replaced with any of PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, or PBCH.

[0221] Furthermore, one embodiment of this disclosure may be applied to any of the following: a terrestrial network, a satellite, or a non-terrestrial network (NTN) using a high-altitude pseudo-satellite (HAPS). Also, one embodiment of this disclosure may be applied to terrestrial networks with large cell sizes, ultra-wideband transmission networks, and other networks where transmission delay is large relative to symbol length or slot length.

[0222] (Antenna port) In one embodiment of this disclosure, an antenna port refers to a logical antenna (antenna group) composed of one or more physical antennas. For example, an antenna port does not necessarily refer to a single physical antenna, but may refer to an array antenna composed of multiple antennas. For example, the number of physical antennas that make up an antenna port is not specified, and it may be defined as the smallest unit on which a terminal station can transmit a reference signal. Alternatively, an antenna port may be defined as the smallest unit on which the weighting of a precoding vector is multiplied.

[0223] <5G NR System Architecture and Protocol Stack> 3GPP is continuing work on the next release of fifth-generation mobile phone technology (also simply called "5G"), which includes the development of new radio access technologies (NR) operating in the frequency range up to 100 GHz. The initial version of the 5G standard was completed at the end of 2017, which will enable the prototyping and commercial deployment of devices (e.g., smartphones) that comply with the 5G NR standard.

[0224] For example, the system architecture as a whole assumes an NG-RAN (Next Generation - Radio Access Network) with gNBs. The gNBs provide the UE-side termination for the user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols of the NG radio access. The gNBs are connected to each other by Xn interfaces. Furthermore, the gNBs are connected to the NGC (Next Generation Core) by Next Generation (NG) interfaces, more specifically to the AMF (Access and Mobility Management Function) (e.g., a specific core entity performing AMF) by NG-C interfaces, and to the UPF (User Plane Function) (e.g., a specific core entity performing UPF) by NG-U interfaces. The NG-RAN architecture is shown in Figure 14 (see, for example, 3GPP TS 38.300 v15.6.0, section 4).

[0225] The NR user plane protocol stack (see, for example, 3GPP TS 38.300, section 4.4.1) includes the PDCP (Packet Data Convergence Protocol (see section 6.4 of TS 38.300)) sublayer, RLC (Radio Link Control (see section 6.3 of TS 38.300)) sublayer, and MAC (Medium Access Control (see section 6.2 of TS 38.300)) sublayer, which are terminated on the network side in gNB. Additionally, a new Access Stratum (AS) sublayer (SDAP: Service Data Adaptation Protocol) is introduced on top of PDCP (see, for example, 3GPP TS 38.300, section 6.5). Furthermore, a control plane protocol stack is defined for NR (see, for example, TS 38.300, section 4.4.2). An overview of Layer 2 functionality is described in section 6 of TS 38.300. The functions of the PDCP sublayer, RLC sublayer, and MAC sublayer are listed in sections 6.4, 6.3, and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in section 7 of TS 38.300.

[0226] For example, the Medium-Access-Control layer handles scheduling and scheduling-related functions, including the multiplexing of logical channels and the handling of various neural networks.

[0227] For example, the Physical Layer (PHY) is responsible for coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping signals to appropriate physical time-frequency resources. The Physical Layer also handles the mapping of transport channels to physical channels. The Physical Layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmitting a particular transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels include uplink physical channels such as PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel), and PUCCH (Physical Uplink Control Channel), and downlink physical channels such as PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel), and PBCH (Physical Broadcast Channel).

[0228] The use cases / deployment scenarios of NR may include enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communication (mMTC), which have diverse requirements in terms of data rate, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps in the downlink and 10 Gbps in the uplink) and effective (user-experienced) data rates that are about three times the data rates provided by IMT-Advanced. On the other hand, for URLLC, more stringent requirements are imposed for ultra-low latency (0.5 ms each for UL and DL for user plane latency) and high reliability (1 - 10-5 within 1 ms). Finally, for mMTC, preferably a high connection density (1,000,000 devices / km 2 ) in urban environments, wide coverage in harsh environments, and extremely long-lived batteries (15 years) for low-cost devices may be required.

[0229] Therefore, an OFDM neurology suitable for one use case (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) may not be effective for other use cases. For example, low-latency services may preferably require a shorter symbol length (and thus a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also known as TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with short delay spreads. The subcarrier spacing may be optimized on a case-by-case basis to maintain similar CP overhead. There may be one or more subcarrier spacing values ​​supported by NR. Accordingly, subcarrier spacings of 15kHz, 30kHz, 60kHz, etc. are currently being considered. The symbol length Tu and subcarrier spacing Δf are directly related by the equation Δf = 1 / Tu. Similar to LTE systems, the term “resource element” can be used to mean the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0230] In the new 5G-NR wireless system, resource grids for subcarriers and OFDM symbols are defined for each neurology and each carrier, for both the uplink and downlink. Each element of the resource grid is called a resource element and is identified based on the frequency index in the frequency domain and the symbol position in the time domain (see 3GPP TS 38.211 v15.6.0).

[0231] <Functional separation between NG-RAN and 5GC in 5G NR> Figure 15 shows the functional separation between NG-RAN and 5GC. The logical nodes of NG-RAN are gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0232] For example, gNB and ng-eNB host the following main functions: - Radio resource management functions such as radio bearer control, radio admission control, connection mobility control, and dynamic allocation (scheduling) of resources to UEs on both uplink and downlink; - Compression, encryption, and integrity protection of the IP header of the data; - Selection of the AMF when the UE attaches if routing to the AMF cannot be determined from the information provided by the UE; - Routing of user plane data toward UPF; - Routing of control plane information to AMF; - Setting up and disconnecting connections; - Scheduling and sending paging messages; - Scheduling and transmission of system notification information (originating from AMF or Operation, Admission, Maintenance functions (OAM)); - Setting up measurements and measurement reporting for mobility and scheduling; - Transport-level packet marking on the uplink; - Session management; - Support for network slicing; - Management of QoS flows and mapping to data radio bearers; - Support for UEs in the RRC_INACTIVE state; - NAS message delivery function; - Sharing of wireless access network; - Dual connectivity; - Close cooperation between NR and E-UTRA.

[0233] The Access and Mobility Management Function (AMF) hosts the following main functions: - A function to terminate Non-Access Stratum (NAS) signaling; - Security of NAS signaling; - Security control of Access Stratum (AS); - Core Network (CN) node-to-node signaling for mobility between 3GPP access networks; - Reachability of the UE in idle mode (including control and execution of paging retransmissions); - Management of registration areas; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization including roaming permission checks; - Mobility management and control (enrollment and policies); - Support for network slicing; - Selection of Session Management Function (SMF).

[0234] Furthermore, the User Plane Function (UPF) hosts the following main functions: - Anchor points for intra-RAT mobility / inter-RAT mobility (where applicable); - External PDU (Protocol Data Unit) session points for interconnection with data networks; - Routing and forwarding of packets; - Packet inspection and enforcement of policy rules in the user plane. - Reporting traffic usage; - Uplink classifier to support routing of traffic flow to data networks; - Branching Point for supporting multi-homed PDU sessions; - QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement); - Verification of uplink traffic (mapping to the QoS flow of the SDF); - Downlink packet buffering and triggering function for downlink data notification.

[0235] Finally, the Session Management Function (SMF) hosts the following main functions: - Session management; - IP address allocation and management for the UE; - Selection and control of the UPF; - Traffic steering setting function in the User Plane Function (UPF) for routing traffic to the appropriate destination; - Enforcement of control plane policies and QoS; - Notification of downlink data.

[0236] <Procedures for RRC connection setup and reconfiguration> Figure 16 shows some of the interactions between the UE, gNB, and AMF (5GC entity) in the NAS part when the UE transitions from RRC_IDLE to RRC_CONNECTED (see TS 38.300 v15.6.0).

[0237] RRC is a higher-layer signaling protocol used for configuring UEs and gNBs. During this transition, the AMF prepares UE context data (including, for example, PDU session context, security key, UE Radio Capability, UE Security Capabilities, etc.) and sends it to the gNB along with an Initial Context Setup Request. The gNB then activates AS security together with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE, to which the UE responds with a SecurityModeComplete message. Subsequently, the gNB sends an RRCReconfiguration message to the UE, and upon receiving an RRCReconfigurationComplete from the UE, the gNB reconfigures itself to set up the Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB). For signaling-only connections, the RRCReconfiguration step is omitted because SRB2 and DRB are not set up. Finally, gNB notifies AMF that the setup procedure is complete with an Initial Context Setup Response.

[0238] Accordingly, this disclosure provides a 5th Generation Core (5GC) entity (e.g., AMF, SMF, etc.) comprising a control circuit that establishes a Next Generation (NG) connection with a gNodeB during operation, and a transmission unit that sends an initial context setup message to the gNodeB via the NG connection during operation so that a signaling radio bearer between the gNodeB and the user equipment (UE) is set up. Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling, including an Information Element (IE), to the UE via the signaling radio bearer. The UE then transmits on the uplink or receives on the downlink based on the resource allocation setting.

[0239] <IMT Usage Scenarios from 2020 Onward> Figure 17 shows some use cases for 5G NR. The 3rd generation partnership project for new radio (3GPP NR) is considering three use cases envisioned by IMT-2020 to support a wide variety of services and applications. The first phase of specification development for enhanced mobile-broadband (eMBB) has been completed. Current and future work will include expanding eMBB support, as well as standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC). Figure 17 shows some examples of conceptual use scenarios for IMT beyond 2020 (see, e.g., ITU-R M.2083 Figure 2).

[0240] URLLC use cases have stringent performance requirements, such as throughput, latency, and availability. URLLC use cases are envisioned as one of the key technologies to enable future applications such as wireless control of industrial production or manufacturing processes, telemedicine surgery, automation of power transmission and distribution in smart grids, and traffic safety. The ultra-high reliability of URLLC is supported by identifying technologies that meet the requirements set by TR 38.913. In NR URLLC in Release 15, a key requirement is that the target user plane latency is 0.5 ms for UL (uplink) and 0.5 ms for DL ​​(downlink). The general URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a 32-byte packet size when the user plane latency is 1 ms.

[0241] From a physical layer perspective, reliability can be improved in many ways. Current room for reliability improvement includes defining a separate CQI table for URLLC, a more compact DCI format, and PDCCH iterations. However, this room for improvement may expand towards achieving ultra-high reliability as NR becomes more stable and developed (in terms of critical requirements for NR URLLC). Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0242] Furthermore, the technical enhancements targeted by NR URLLC aim to improve latency and reliability. Technical enhancements for latency improvement include configurable neurology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level iteration on data channels, and preemption on downlink. Preemption means that a transmission for which a resource has already been allocated is stopped, and that allocated resource is used for other transmissions with lower latency / higher priority requirements that are requested later. Thus, transmissions that were already permitted are replaced by later transmissions. Preemption is applicable regardless of the specific service type. For example, a transmission of service type A (URLLC) may be replaced by a transmission of service type B (eMBB, etc.). Technical enhancements for reliability improvement include a dedicated CQI / MCS table for the 1E-5 target BLER.

[0243] A key characteristic of mMTC (massive machine type communication) use cases is the extremely large number of connected devices that typically transmit relatively small amounts of data that are less susceptible to latency. These devices require low cost and very long battery life. From a noise reduction (NR) perspective, utilizing a very narrow bandwidth is one solution that saves power from the user interface (UE) and extends battery life.

[0244] As mentioned above, the scope of reliability improvements in NR is expected to broaden. High reliability or very high reliability is a critical requirement in all cases, for example, for URLLC and mMTC. Several mechanisms can improve reliability from both a radio and network perspective. Generally, there are two to three key areas that can help improve reliability. These areas include compact control channel information, data channel / control channel repetition, and diversity in the frequency, time, and / or spatial domains. These areas are generally applicable to reliability improvements regardless of the specific communication scenario.

[0245] Regarding NR URLLC, further use cases with more stringent requirements are envisioned, such as factory automation, transportation, and power distribution. These stringent requirements include high reliability (up to 10⁻⁶ levels), high availability, packet size up to 256 bytes, and time synchronization down to a few microseconds (depending on the use case, the value can be 1 microsecond or a few microseconds depending on the frequency range and short latency of approximately 0.5 ms to 1 ms (e.g., 0.5 ms latency in the target user plane)).

[0246] Furthermore, for NR URLLC, several technical enhancements may be available from the perspective of the physical layer. These technical enhancements include enhancements to the Physical Downlink Control Channel (PDCCH) related to compact DCI, repetition of the PDCCH, and increased monitoring of the PDCCH. Also, the enhancement of UCI (Uplink Control Information) is related to the enhancement of enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback. In addition, there may be enhancements to the PUSCH related to mini-slot level hopping, and enhancements to retransmission / repetition. The term "mini-slot" refers to a Transmission Time Interval (TTI) that contains fewer symbols than a slot (a slot has 14 symbols).

[0247] <QoS Control> The 5G Quality of Service (QoS) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (GBR: Guaranteed Bit Rate QoS flow) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flow). Therefore, at the NAS level, a QoS flow is the finest granularity QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI) that is carried in an encapsulation header via the NG-U interface.

[0248] For each UE, the 5GC establishes one or more PDU sessions. For each UE, in accordance with the PDU session, the NG-RAN establishes at least one Data Radio Bearer (DRB) as shown above referring to, for example, Figure 16. Also, additional DRBs for the QoS flows of that PDU session can be set later (it depends on the NG-RAN when to set). The NG-RAN maps the packets belonging to various PDU sessions to various DRBs. While the NAS-level packet filters in the UE and 5GC associate UL packets and DL packets with QoS flows, the AS-level mapping rules in the UE and NG-RAN associate UL QoS flows and DL QoS flows with DRBs.

[0249] Figure 18 shows the 5G NR non-roaming reference architecture (see TS 23.501 v16.1.0, section 4.23). The Application Function (AF) (for example, the external application server that hosts 5G services illustrated in Figure 17) communicates with the 3GPP core network to provide services. For example, accessing the Network Exposure Function (NEF) or communicating with the policy framework for policy control (for example, QoS control) (see Policy Control Function (PCF)) to support applications that affect traffic routing. Based on operator deployment, the Application Function considered to be trusted by the operator can communicate directly with the relevant Network Function. The Application Function not permitted by the operator to directly access the Network Function communicates with the relevant Network Function using the external exposure framework via the NEF.

[0250] FIG. 18 further shows additional functional units of the 5G architecture, namely, Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN, e.g., operator services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and operate in a cloud computing environment.

[0251] Therefore, in the present disclosure, in operation, a request including QoS requirements for at least one of the URLLC service, eMMB service, and mMTC service is transmitted to at least one of the functions of the 5GC (e.g., NEF, AMF, SMF, PCF, UPF, etc.) in order to establish a PDU session including a radio bearer between the gNodeB and the UE according to the QoS requirements. An application server (e.g., AF of the 5G architecture) is provided, which includes a transmission unit and a control circuit that performs services using the established PDU session in operation.

[0252] This disclosure can be implemented in software, hardware, or software in conjunction with hardware. Each functional block used in the description of the above embodiments may be implemented in part or in whole as an integrated circuit (LSI), and each process described in the above embodiments may be controlled in part or in whole by a single LSI or a combination of LSIs. An LSI may consist of individual chips, or it may consist of a single chip that includes some or all of the functional blocks. An LSI may have data inputs and outputs. Depending on the degree of integration, LSIs may be referred to as ICs, system LSIs, super LSIs, or ultra LSIs.

[0253] The method of integration is not limited to LSIs; it may also be implemented using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, FPGAs (Field Programmable Gate Arrays) that can be programmed after LSI manufacturing, or reconfigurable processors that allow for the reconfiguration of the connections and settings of circuit cells within the LSI, may also be used. This disclosure may be implemented as digital or analog processing.

[0254] Furthermore, if advancements in semiconductor technology or related technologies lead to the emergence of integrated circuit technologies that replace LSIs, then naturally, these technologies could be used to integrate functional blocks. The application of biotechnology, for example, is a possible possibility.

[0255] This disclosure is applicable to all types of devices, systems, and equipment having communication capabilities (collectively referred to as communication equipment). Communication equipment may include a radio transceiver and a processing / control circuit. A radio transceiver may include a receiver and a transmitter, or both as functions. A radio transceiver (transmitter, receiver) may include an RF (Radio Frequency) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or similar. Non-exclusive examples of communication devices include telephones (mobile phones, smartphones, etc.), tablets, personal computers (PCs) (laptops, desktops, notebooks, etc.), cameras (digital still / video cameras, etc.), digital players (digital audio / video players, etc.), wearable devices (wearable cameras, smartwatches, tracking devices, etc.), game consoles, digital book readers, telehealth / telemedicine devices, vehicles or mobile transport with communication capabilities (cars, airplanes, ships, etc.), and combinations of the above-mentioned devices.

[0256] Communication devices are not limited to portable or movable devices, but also include all kinds of non-portable or fixed devices, devices, and systems, such as smart home devices (appliances, lighting equipment, smart meters or measuring instruments, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0257] Communication includes data communication via cellular systems, wireless LAN systems, and communication satellite systems, as well as data communication using combinations of these.

[0258] Furthermore, the communication device also includes devices such as controllers and sensors that are connected to or linked to a communication device that performs the communication functions described in this disclosure. For example, this includes controllers and sensors that generate control signals and data signals used by the communication device that performs the communication functions of the communication device.

[0259] Furthermore, communication equipment includes infrastructure facilities such as base stations, access points, and any other devices, devices, and systems that communicate with or control the aforementioned non-limited types of equipment.

[0260] A terminal according to one embodiment of the present disclosure comprises a control circuit that determines a transmission opportunity based on a control signal for uplink transmission using either a cell-specific offset or a parameter different from the cell-specific offset, and a transmission circuit that performs the uplink transmission at the transmission opportunity.

[0261] In one embodiment of the present disclosure, the control circuit uses the cell-specific offset when the uplink transmission is triggered by the control signal.

[0262] In one embodiment of the present disclosure, the control circuit selects an earlier transmission opportunity from among the transmission opportunities that occur after the timing based on the cell-specific offset.

[0263] In one embodiment of the present disclosure, the control circuit selects a transmission opportunity included in the set of transmission opportunities that falls after the timing based on the cell-specific offset.

[0264] In one embodiment of the present disclosure, the control signal includes information indicating the use of either the cell-specific offset or the parameter.

[0265] In one embodiment of the present disclosure, the parameter is either a terminal-specific offset or a parameter relating to the transmission opportunity available to the terminal.

[0266] In one embodiment of the present disclosure, the control signal includes either first information associated with the cell-specific offset or second information associated with the parameter.

[0267] In one embodiment of the present disclosure, the uplink signal is a signal of a random access channel (RACH), the first information includes information indicating a contention-based RACH, and the second information includes information indicating a non-contention-based RACH.

[0268] In one embodiment of the present disclosure, the parameter is an offset different from each of the cell-specific offset and the terminal-specific offset.

[0269] In one embodiment of the present disclosure, the offset is an offset in units of slots including the transmission opportunity.

[0270] In one embodiment of the present disclosure, the offset is an offset in units of the transmission opportunity.

[0271] A base station according to one embodiment of the present disclosure includes a control circuit that determines a transmission opportunity using either a cell-specific offset or a parameter different from the cell-specific offset based on a control signal related to uplink reception, and a reception circuit that performs the uplink reception in the transmission opportunity.

[0272] In a communication method according to one embodiment of the present disclosure, a terminal determines a transmission opportunity using either a cell-specific offset or a parameter different from the cell-specific offset based on a control signal related to uplink transmission, and performs the uplink transmission in the transmission opportunity.

[0273] In a communication method according to one embodiment of the present disclosure, a base station determines which of a first offset specific to a terminal and a second offset specific to a cell to use based on a control signal related to uplink reception, and performs the uplink reception based on the determined offset.

[0274] All disclosures in the specification, drawings, and abstract contained in the Japanese application 2021-055853, filed on March 29, 2021, are incorporated herein by reference. [Industrial applicability]

[0275] One aspect of this disclosure is useful for wireless communication systems. [Explanation of Symbols]

[0276] 100 base stations 101,206 antennas 102,207 Wireless receiver 103 PRACH detection unit 104 Data Reception Processing Unit 105 Timing control information generation unit 106,202 Data Generation Unit 107 Data transmission processing unit 108,205 Wireless Transmitter 109,209 Control Unit 200 terminals 201 PRACH generation section 203 Location information acquisition unit 204 Timing adjustment section 208 Demodulation / Decoding Section

Claims

1. A control circuit that determines the transmission opportunity using a cell-specific offset based on a control signal for uplink transmission, In the aforementioned transmission opportunity, the transmission circuit that performs the uplink transmission, It is equipped with, When the uplink transmission is triggered using the downlink control channel (Physical Downlink Control Channel (PDCCH)), the control circuit determines the transmission opportunity to be a RACH occasion (RO) that is after the timing based on the cell-specific offset and corresponds to one SSB index set from multiple options by the base station. Terminal.

2. The control circuit selects an earlier transmission opportunity from among the transmission opportunities that are later than the timing based on the cell-specific offset. The terminal according to claim 1.

3. The control circuit selects a transmission opportunity included in the set of transmission opportunities that occurs after the timing based on the cell-specific offset. The terminal according to claim 1.

4. The control circuit determines the transmission opportunity based on the control signal, using either the cell-specific offset or a parameter different from the cell-specific offset. The terminal according to claim 1.

5. The aforementioned parameters are parameters relating to the transmission opportunities available to the terminal. The terminal according to claim 4.

6. The control signal includes either first information associated with the cell-specific offset or second information associated with the parameter. The terminal according to claim 4.

7. The aforementioned uplink transmission is a physical random access channel (PRACH) transmission. The terminal according to claim 1.

8. The cell-specific offset is an offset per slot including the transmission opportunity. The terminal according to claim 1.

9. A control circuit that determines a transmission opportunity using a cell-specific offset based on a control signal related to uplink reception, In the aforementioned transmission opportunity, the receiving circuit that performs the uplink reception, It is equipped with, When the uplink reception is triggered using the downlink control channel (Physical Downlink Control Channel (PDCCH)), the control circuit determines the transmission opportunity to be a RACH occasion (RO) that is after the timing based on the cell-specific offset and corresponds to one SSB index set by multiple sources for the terminal. Base station.

10. The device is, Based on the control signal for uplink transmission, the cell-specific offset is used to determine the transmission opportunity. During the aforementioned transmission opportunity, the uplink transmission is performed. When the uplink transmission is triggered using the downlink control channel (Physical Downlink Control Channel (PDCCH)), the transmission opportunity is determined to be a RACH occasion (RO) that is after the timing based on the cell-specific offset and corresponds to one SSB index set by the base station from among multiple options. Communication method.

11. The base station is, Based on the control signal for uplink reception, the cell-specific offset is used to determine the transmission opportunity. During the aforementioned transmission opportunity, the aforementioned uplink reception is performed, When the uplink reception is triggered using the downlink control channel (Physical Downlink Control Channel (PDCCH)), the transmission opportunity is determined to be a RACH occasion (RO) that is after the timing based on the cell-specific offset and corresponds to one SSB index set by multiple sources for the terminal. Communication method.

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