Terminal, base station, communication method, and integrated circuit

Abstract

This terminal comprises: a reception circuit that receives control information regarding a reference point for a reference time in control of the transmission timing of an uplink signal in a first cell to a second cell different from the first cell; and a control circuit that controls the transmission timing on the basis of the control information.

Description

Terminal, base station, and communication method

[0001] The present disclosure relates to a terminal, a base station, and a communication method.

[0002] In the standardization of 5G, new radio access technology (NR) has been specified by 3GPP, and the NR Release 15 (Rel.15) specification has been published.

[0003] 3GPP, TR 38.821, V16.1.0 “Solutions for NR to support non-terrestrial networks (NTN) (Release 16)”, 2021-05

[0004] However, there is room for further study on methods for improving the accuracy of signal transmission timing control.

[0005] Non-limiting examples of the present disclosure contribute to providing a terminal, a base station, and a communication method that can improve the accuracy of signal transmission timing control.

[0006] A terminal according to one embodiment of the present disclosure includes a receiving circuit that receives, in a first cell, control information regarding a reference point for a reference time in controlling the transmission timing of an uplink signal to a second cell different from the first cell, and a control circuit that controls the transmission timing based on the control information.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to an embodiment of the present disclosure, it is possible to improve the accuracy of signal transmission timing control.

[0009] Further advantages and benefits of certain aspects of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features.

[0010] 1 is a diagram showing an example of delay estimation in a service link and a feeder link; 2 is a sequence diagram showing an example of a conditional handover; 3 is a diagram showing an example of a handover; 4 is a block diagram showing an example of the configuration of a part of a base station; 5 is a block diagram showing an example of the configuration of a terminal; 6 is a block diagram showing an example of the configuration of a base station; 7 is a block diagram showing an example of the configuration of a terminal; 8 is a diagram showing an example of a handover; 9 is a diagram showing an example of a handover; 10 is a diagram showing an example of a handover; 11 is a diagram showing an example of a method for specifying epoch time; 12 is a diagram showing an example of a method for specifying epoch time; 13 is a diagram showing an example of notification of assistance information; 14 is a diagram of an exemplary architecture of a 3GPP NR system; 15 is a schematic diagram showing functional separation between NG-RAN and 5GC; 16 is a sequence diagram of a procedure for setting up / resetting an RRC (Radio Resource Control) connection; 17 is a schematic diagram showing usage scenarios of enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communications (URLLC), and

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

[0012] [Regarding Non-Terrestrial Networks (NTN)] NR Rel. 15 specifies radio 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) (see, for example, Non-Patent Document 1).

[0013] In an NTN environment, satellite coverage areas (e.g., one or more cells) for terminals in the sky, such as terrestrial terminals (e.g., user equipment (UE)), aircraft, or drones, are formed by beams from the satellite. The round trip time (RTT) of radio waves propagating between the terminal and the satellite is determined by the satellite's altitude (e.g., up to approximately 36,000 km) and the angle seen from the terminal, i.e., the relative positions of the satellite and the terminal.

[0014] For example, Non-Patent Document 1 states that in NTN, the round trip time (RTT) of radio wave propagation between a base station and a terminal takes a maximum of approximately 540 ms.

[0015] Furthermore, Non-Patent Document 1 states that in NTN, a delay difference of up to about 10 ms occurs depending on the position of the terminal within the beam (or coverage area or cell) (for example, the difference between the farthest position and the closest position from the satellite within the beam).

[0016] Furthermore, in the case of non-geostationary satellites such as low-earth orbit (LEO) satellites, the satellites move at high speeds of around 7.6 km per second, so the amount of propagation delay varies more dramatically than in terrestrial networks.

[0017] (Timing Control) In NR, for example, in order to align the reception timing of signals transmitted from each terminal at the base station (also referred to as gNB), each terminal may perform timing control (e.g., timing adjustment) based on information for correcting (adjusting) the timing (e.g., called a "Timing Advance (TA) command") notified from the base station.

[0018] As mentioned above, in NTN, propagation delays vary more dramatically than in terrestrial networks, so terminals calculate the round-trip delay time between the terminal and the base station, correct the timing, and then transmit the signal.

[0019] FIG. 1 is a diagram showing an example of processing (for example, delay time estimation processing) in NTN.

[0020] The delay time of a wireless link (e.g., referred to as a "service link") between a terminal and a satellite may be calculated based on, for example, location information of the terminal and information about the satellite's orbit or location. The location information of the terminal may be acquired by the terminal using, for example, a Global Navigation Satellite System (GNSS). The information about the satellite's orbit or location may be notified (e.g., broadcast) from a base station to the terminal as, for example, "satellite ephemeris information (or satellite ephemeris)."

[0021] Furthermore, the delay time of the wireless link (e.g., called a "feeder link") between a terrestrial base station or gateway (GW) and a satellite may be calculated, for example, at the terminal based on a common TA parameter broadcast from the base station.

[0022] Since the delay time of the feeder link changes with the movement of the satellite, information on the amount of change in delay time, such as common TA drift and common TA drift variation, may be notified to the terminal as common TA parameters in addition to the delay time of the feeder link at a certain point in time.

[0023] In this way, in NTN, the terminals correct (e.g., compensate) the round-trip delay times of the service link and feeder link before transmitting uplink signals, which enables signals transmitted from each terminal to be received at the base station within a predetermined time difference.

[0024] (Regarding control information for NTN) At least one of the following information or parameters may be included as control information for NTN from a base station to a terminal. The control information for NTN may be notified to the terminal by broadcast information such as a System Information Block (SIB). Ephemeris: satellite ephemeris information Common TA parameters Epoch time: reference time for satellite ephemeris information and common TA parameters Validity duration for UL sync information: validity period for SIB information t-Service (the timing information on when the serving cell is going to stop serving the area): remaining period of the cell Cell reference location: reference location for cell selection or handover Cell specific K_offset: offset for scheduling K_mac: information on the difference between the downlink transmission reference point and the uplink reception synchronization reference point

[0025] Here, the epoch time is, for example, a reference time for the satellite ephemeris and the common TA parameters. The satellite ephemeris and the common TA parameters are generated based on the epoch time, and the values ​​at the time of the epoch time are notified. The terminal may, for example, calculate the satellite position based on the epoch time and satellite ephemeris information, and calculate the feeder link delay time based on the epoch time and the common TA parameters.

[0026] Also, for example, the satellite ephemeris of the serving cell and the epoch time of the common TA parameter may be expressed by a system frame number (SFN) and a subframe number instead of absolute time, and may be notified to the terminal.

[0027] In a terminal, for example, the time at the beginning of a subframe (subframe start time) of the notified SFN and subframe number is interpreted as the epoch time. Here, because there is a propagation delay between the base station and the terminal, it is expected that the epoch time indicates the subframe start time at a point in time during signal propagation from the base station to the terminal, for example, a "reference point (RP)" should be clarified. For example, the reference point for the epoch time may be the point at which the uplink signal is synchronized (uplink synchronization reference point). For example, the epoch time may be the subframe start time at the point at which the uplink signal is synchronized.

[0028] The uplink signal synchronization reference point may be, for example, a point at which signals transmitted from each terminal in a cell to a base station are synchronized. For example, the uplink signal synchronization reference point may be the transmitting end of the base station, the transmitting end of the satellite, or any point between the satellite and the base station.

[0029] The terminal may calculate the satellite position and the common TA value at the transmission timing of the terminal, taking into account the propagation delay between the reference point and the terminal, for example, and transmit data.

[0030] Note that the satellite ephemeris information may include, for example, the following parameters: Position and velocity state vector ephemeris format, Position (m), Velocity (m / s), Orbital parameter ephemeris format, Semi-major axis α (m), Eccentricity e, Argument of periapsis ω (rad), Longitude of ascending node (Ω rad), Inclination i (rad), Mean anomaly M (rad) at epoch time

[0031] The common TA parameters may include, for example, the following parameters: TACommon: common TA value at epoch time TACommonDrift: variation of the common TA value TACommonDriftVariation: variation of the variation of the common TA value

[0032] The satellite ephemeris information and common TA parameters are sometimes called "assistance information."

[0033] The terminal calculates the feeder link delay (round trip delay) Delay according to the following equation (1), for example, using the parameters included in the control information for the NTN. common (t) may be calculated.

[0034] The feeder link delay may be the delay between the satellite and the point (reference point) where the upstream signal is synchronized.

[0035] (Regarding notification of neighboring cell information) In NR, a terminal in RRC_IDLE state or RRC_INACTIVE state performs neighbor cell measurement for cell reselection.

[0036] Information about neighboring cells used for neighboring cell measurement may be notified (e.g., broadcast) from a base station to a terminal. For example, the information about neighboring cells may be broadcast to a terminal by SIB type 2 (SIB2). The information about neighboring cells may include at least one of radio parameters such as carrier frequency or subcarrier spacing (SCS), and information about the time position of the SSB to be measured, called SSB measurement timing configuration (SMTC). Note that SSB stands for Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block. In neighboring cell measurement, quality measurements such as Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), and Signal to Interference and Noise Ratio (SINR) of the neighboring cells may be performed.

[0037] In addition, in NR, for example, a terminal in the RRC_CONNECTED state performs neighbor cell measurements for handover in response to an instruction from a base station and executes handover.

[0038] Information about neighboring cells used in neighboring cell measurement for handover (e.g., the same as the information about neighboring cells described above) may be notified to the terminal by, for example, terminal-dedicated RRC signaling (e.g., dedicated RRC signaling). For example, the information about neighboring cells may be notified from a base station (e.g., a serving cell) to which the terminal is connected by an "RRC reconfiguration message."

[0039] In NTN, information about neighboring cells may include notification of satellite ephemeris information and common TA parameters of the neighboring cells. The satellite ephemeris information and common TA parameters of the neighboring cells may be used, for example, by a terminal to adjust a measurement window in accordance with satellite movement. Furthermore, when performing handover, the terminal may perform timing adjustment (TA) for random access transmission (e.g., random access channel (RACH) transmission) using the satellite ephemeris information and common TA parameters of the neighboring cells.

[0040] For example, there is room for further consideration regarding the method of reporting information about neighboring cells.

[0041] (About conditional handover) In NR (e.g., Release 16), conditional handover (CHO) was introduced.

[0042] FIG. 2 is a sequence diagram illustrating an example of a CHO.

[0043] In CHO, for example, a terminal receives in advance an RRC reconfiguration message including handover conditions (hereinafter referred to as "HO conditions"). For example, a handover source base station (e.g., also referred to as a source base station, source gNB, or source cell) may transmit a handover request (HO request message) to a handover destination base station (e.g., also referred to as a target base station, target gNB, or target cell). The target base station may transmit a handover request response (HO request acknowledge message) to the source base station. Then, the source base station may transmit an RRC reconfiguration message including the HO conditions to, for example, a terminal (UE) to be handed over.

[0044] The terminal may periodically evaluate (or check, determine, or monitor) whether the HO condition is met. If the HO condition is met, the terminal may perform handover and perform an access process (e.g., RACH process) to a new cell (target base station).

[0045] For example, in Release 16, the HO condition is based on neighbor cell measurements. In the neighbor cell measurement condition, the terminal may perform handover if measurement results of neighbor cell parameters such as RSRP, RSRQ, and SINR satisfy specified criteria.

[0046] In NTN, the addition of at least one of a timing reference condition and a location reference condition in addition to a condition based on neighbor cell measurements is being discussed as an HO condition.

[0047] In timing-based CHO, for example, the terminal may perform handover within a pre-notified time range, or may perform neighbor cell measurement within a pre-notified time range and perform handover if the neighbor cell measurement result satisfies a specified criterion.

[0048] In location-based CHO, for example, the terminal may perform handover when the distance between the terminal and a reference location of a cell to which the terminal connects (e.g., a current cell or a serving cell) is greater than a pre-notified value. Alternatively, the terminal may perform handover when the distance between the terminal and the reference location of the current cell is greater than the distance between the terminal and the reference location of a neighboring cell (or is greater by a specified distance).

[0049] In this way, NTN provides terminals with HO conditions in advance, enabling handover with reduced delay even in cases where cells are switched rapidly, such as in LEO.

[0050] Conditional Handover (CHO) has been described above.

[0051] As described above, in NTN, the epoch time notified from the base station to the terminal can be expressed by the SFN and the subframe number.

[0052] 3 is a diagram showing an example of a handover process in an NTN. In FIG. 3, for example, a UE receives an RRC reconfiguration message from a serving cell (or source cell) gNB1, which includes satellite ephemeris information of a target cell (or neighboring cell) gNB2, a common TA parameter, and information about epoch time. For example, upon receiving the information about epoch time, the terminal calculates the epoch time based on the SFN and subframe timing corresponding to the received signal from gNB1.

[0053] Here, the information about epoch time received by the UE along with the information about the satellite ephemeris and common TA parameters of a neighboring cell (e.g., the cell of gNB2 in FIG. 3 ) may be a value based on the SFN and subframe number of the neighboring cell. Also, for example, as shown in FIG. 3 , the epoch time (e.g., SFN=10, subframe 3) in the current cell (e.g., the cell of gNB1) may differ from the epoch time (e.g., SFN=25, subframe 0) in the neighboring cell (e.g., the cell of gNB2). Therefore, the UE may not correctly interpret the epoch time corresponding to gNB2 from the information about epoch time received from gNB1. Furthermore, for example, if the UE does not identify (or share) a reference point for the epoch time for the satellite ephemeris and common TA parameters of the neighboring cell, it may not be able to accurately calculate the epoch time. This may easily reduce the accuracy of estimating the satellite position using the satellite ephemeris and estimating the feeder link delay amount using the common TA parameters.

[0054] It should be noted that "interpretation" may also be replaced with, for example, "identification," "judgment," "determination," "decision," "calculation," or "understanding."

[0055] In a non-limiting embodiment of the present disclosure, for example, a method is described in which a terminal correctly identifies an epoch time and a reference point of the epoch time, and improves the accuracy of the terminal's estimation of a satellite position using satellite ephemeris and the estimation of a feeder link delay amount using common TA parameters. For example, the terminal may obtain information for interpreting the epoch time of a neighboring cell from the network side.

[0056] [Overview of Communication System] A communication system according to an embodiment of the present disclosure includes a base station 100 and a terminal 200.

[0057] Fig. 4 is a block diagram showing an example configuration of a portion of base station 100. In base station 100 shown in Fig. 4, a control unit (e.g., corresponding to a control circuit) determines, in a first cell (e.g., a serving cell), control information related to a reference point for a reference time (e.g., epoch time) in controlling the transmission timing of an uplink signal to a second cell different from the first cell. A transmission unit (e.g., corresponding to a transmission circuit) transmits the control information.

[0058] Fig. 5 is a block diagram showing an example configuration of a portion of terminal 200. In terminal 200 shown in Fig. 5, a receiving unit (e.g., corresponding to a receiving circuit) receives, in a first cell (e.g., a serving cell), control information related to a reference point for a reference time (e.g., epoch time) in controlling the transmission timing of an uplink signal to a second cell different from the first cell. A control unit (e.g., corresponding to a control circuit) controls the transmission timing based on the control information.

[0059] 6 is a block diagram showing an example of the configuration of base station 100 according to this embodiment. Base station 100 includes, for example, data generation section 101, control section 102, data transmission processing section 103, wireless transmission section 104, antenna 105, wireless reception section 106, and data reception processing section 107.

[0060] At least one of the data generation unit 101, the control unit 102, the data transmission processing unit 103, and the data reception processing unit 107 shown in Fig. 6 may be included in, for example, the control unit shown in Fig. 4. Also, at least one of the wireless transmission unit 104 and the antenna 105 shown in Fig. 6 may be included in, for example, the transmission unit shown in Fig. 4.

[0061] The data generating unit 101 generates, for example, a downlink signal for each terminal 200, and outputs the generated downlink signal to the data transmission processing unit 103. The downlink signal generated in the data generating unit 101 may include at least any of signals such as user data (for example, a Physical Downlink Shared Channel (PDSCH)), a control signal (for example, a Physical Downlink Control Channel (PDCCH)), a synchronization signal (for example, an SSB), a reference signal (RS: Reference Signal), and Medium Access Control (MAC) control information.

[0062] The control unit 102 may generate system information (e.g., broadcast information) such as a Master Information Block (MIB) or an SIB, and individual control information (e.g., RRC control information such as an RRC reconfiguration message). The control unit 102 outputs the generated information to the data transmission processing unit 103.

[0063] For example, basic control information including the SFN may be notified to the terminal 200 by the MIB. Furthermore, for example, the SIB may include information (e.g., minimum necessary information) for accessing a cell (e.g., base station 100), neighboring cell information for neighboring cell measurement or cell selection, and other broadcast information. Furthermore, the system information (e.g., SIB) may include control information for the NTN, including at least one of parameters corresponding to the cell, such as satellite ephemeris, common TA parameters, Epoch time, and expiration time. Furthermore, the system information (e.g., SIB) may include information for neighboring cells of the NTN, including at least one of parameters corresponding to the neighboring cells, such as satellite ephemeris, common TA parameters, and Epoch time. The information for neighboring cells of the NTN may include information corresponding to each of the other cells (e.g., neighboring cells).

[0064] An example of a method for transmitting information for neighboring cells (including, for example, at least one of satellite ephemeris, common TA parameters, and Epoch time) will be described later.

[0065] Furthermore, the control unit 102 may exchange cell information or SIB information with other base stations for handover or the like (for example, a handover request or a handover request response).

[0066] The data transmission processing unit 103 encodes and modulates, for example, the signal input from the data generation unit 101 and the signal input from the control unit 102 , and outputs the modulated signal to the radio transmission unit 104 .

[0067] The radio transmitting section 104 performs transmission processing such as D / A conversion, up-conversion, and amplification on the signal input from the data transmission processing section 103 , and transmits the radio signal after transmission processing from the antenna 105 .

[0068] The radio receiving unit 106 performs reception processing such as down-conversion and A / D conversion on a data signal (e.g., a Physical Uplink Shared Channel (PUSCH)), a control signal (e.g., a Physical Uplink Control Channel (PUCCH)), or a random access signal (e.g., a Physical Random Access Channel (PRACH)) from the terminal 200 received via the antenna 105, and outputs the signal after the reception processing to the data reception processing unit 107.

[0069] The data reception processing unit 107 performs, for example, channel estimation, demodulation processing, and decoding processing on the received signal input from the radio receiving unit 106. The data reception processing unit 107 outputs the decoded signal.

[0070] [Configuration of Terminal] Next, an example of the configuration of the terminal 200 will be described.

[0071] 7 is a block diagram showing an example of the configuration of terminal 200 according to this embodiment. Terminal 200 includes, for example, antenna 201, wireless receiving section 202, data reception processing section 203, location information acquisition section 204, timing adjustment section 205, data transmission processing section 206, and wireless transmitting section 207.

[0072] At least one of the data reception processing unit 203, the location information acquisition unit 204, the timing adjustment unit 205, and the data transmission processing unit 206 shown in Fig. 7 may be included in, for example, the control unit shown in Fig. 5. Also, at least one of the antenna 201 and the wireless receiving unit 202 shown in Fig. 7 may be included in, for example, the receiving unit shown in Fig. 5.

[0073] The radio receiving unit 202 performs receiving processing such as down-conversion and A / D conversion on downlink signals, such as data signals (e.g., PDSCH) and control signals (e.g., PDCCH) from the base station 100, received via the antenna 201, and outputs the processed signals to the data receiving processing unit 203 and outputs information on the receiving timing to the timing adjustment unit 205.

[0074] The data reception processing unit 203 performs demodulation processing and decoding processing on a received signal (e.g., PDCCH or PDSCH) input from the radio receiving unit 202, for example. The control signal (e.g., PDCCH) may include, for example, allocation information of a downlink data signal (e.g., PDSCH) or allocation information of an uplink data signal (e.g., PUSCH). The downlink data signal (e.g., PDSCH) may include, for example, user data. The downlink data signal (e.g., PDSCH) may include broadcast information such as system information, RRC control information (e.g., RRC reconfiguration message), MAC Control Element (MAC CE) control information, a RACH response (e.g., msg2, also referred to as Random Access Response (RAR)), or a TA command.

[0075] In addition, the data reception processing unit 203 performs reception processing of, for example, information for NTN (e.g., including at least one of satellite ephemeris, common TA parameters, and Epoch time) contained in broadcast information or RRC control information (e.g., an RRC Reconfiguration message), and information used for cell selection, neighboring cell measurement, or handover, and outputs the signal after reception processing to the timing adjustment unit 205.

[0076] The location information acquisition unit 204 acquires, for example, location information (information such as latitude, longitude, and altitude) of the terminal 200. The location information of the terminal 200 may be acquired by a GNSS function such as the Global Positioning System (GPS). The location information acquisition unit 204 outputs the acquired location information of the terminal 200 to the timing adjustment unit 205.

[0077] The timing adjustment section 205 controls (adjusts) the transmission timing of a transmission signal (uplink signal), for example, and outputs information relating to timing adjustment to the radio transmission section 207.

[0078] For example, the timing adjustment unit 205 may calculate the distance between the terminal 200 and a satellite based on the location information of the terminal 200 input from the location information acquisition unit 204 and the satellite ephemeris information input from the data reception processing unit 203. Then, the timing adjustment unit 205 calculates the distance between the terminal 200 and a satellite and the radio wave propagation speed (approximately 3×10 8 m / s), the propagation delay time between the satellite and the terminal 200 (e.g., the service link) may be calculated.

[0079] Furthermore, for example, the timing adjustment unit 205 may calculate the propagation delay time between the base station 100 and the satellite (for example, a feeder link) based on the common TA parameters input from the data reception processing unit 203.

[0080] For example, the timing adjustment unit 205 may use information on the epoch time when estimating the satellite position based on the satellite ephemeris information and / or when estimating the feeder link delay amount based on the common TA parameters.

[0081] Furthermore, the timing adjustment unit 205 may adjust the transmission timing of an uplink signal (for example, uplink data or a RACH signal) by using, for example, the propagation delay times of the service link and the feeder link. For example, the timing adjustment unit 205 adjusts the transmission timing of an uplink signal (for example, uplink data or a RACH signal) by compensating for the propagation delay times of the service link and the feeder link, so that the signal is received at a specified timing in the base station 100. TA ) and timing adjustment may be performed according to the

[0082] In formula (2), N TA indicates the TA value notified by the TA command, for example, and N TAoffset indicates the offset to the TA value, and T c indicates the basic time unit. UEspecific denotes a terminal-specific TA value based on the service link delay time estimated from the location information of the terminal 200 and the position of the satellite, and T commonindicates a common TA value based on the feeder link delay time calculated from the common TA parameter. The first term of equation (2) is the same as, for example, the Rel. 15 NR specification, and in equation (2), the value of the first term is the terminal-specific TA value (T UEspecific ) and common TA value (T common ) is added.

[0083] In addition, the timing adjustment unit 205 may perform timing adjustment according to the timing adjustment value shown in equation (2), for example, based on the reception timing of a signal (e.g., an SSB signal) received from the base station 100 and input from the radio receiving unit 202.

[0084] The data transmission processing unit 206 performs, for example, error correction coding and modulation processing on the input transmission data, and outputs the modulated signal to the radio transmission unit 207. The transmission data may be, for example, a signal (e.g., PUSCH) transmitted in time and frequency resources allocated by the base station 100, or a signal (e.g., PRACH signal, also referred to as msg1) transmitted in random access processing.

[0085] The radio transmitting unit 207 performs transmission processing such as D / A conversion, up-conversion, and amplification on the signal input from the data transmission processing unit 206, and transmits the radio signal after the transmission processing from the antenna 201. The radio transmitting unit 207 may transmit the signal at a timing specified by information input from the timing adjusting unit 205, for example.

[0086] [Example of Operation of Base Station and Terminal] Next, an example of operation of base station 100 and terminal 200 will be described.

[0087] In this embodiment, for example, base station 100 generates information about the epoch time of a neighbor cell using the system frame number (SFN) and subframe number in the serving cell of base station 100. Base station 100 may, for example, convert the SFN and subframe number of the epoch time of the neighbor cell into the SFN and subframe number in the serving cell of base station 100, regenerate information about the epoch time based on the converted SFN and subframe number, and notify terminal 200 in the serving cell of base station 100.

[0088] The terminal 200 interprets the epoch time of the neighboring cell based on the SFN and subframe number of the serving cell or the cell from which the terminal 200 has received information about the epoch time.

[0089] Furthermore, the reference point of the epoch time of the neighboring cell may be set to a point where uplink signals in the neighboring cell are synchronized (for example, an uplink synchronization reference point). Note that the reference point of the epoch time of the neighboring cell may be defined in advance in a specification (for example, a standard). Alternatively, information regarding the reference point of the epoch time of the neighboring cell (for example, indicating that it is a point where uplink signals in the neighboring cell are synchronized) may be notified to terminal 200.

[0090] The following describes a method for transmitting information (including, for example, satellite ephemeris, common TA parameters, and epoch time) for neighboring cells transmitted from base station 100, and a method for interpreting epoch time in terminal 200. As examples, two methods (method 1 and method 2) for processing at the time of handover will be described.

[0091] <Method 1> In method 1, the base station 100 converts, for example, the epoch time (for example, SFN and subframe number) of a neighboring cell into a value based on the SFN and subframe number in the base station 100. For example, control information related to the epoch time notified from the base station 100 to the terminal 200 indicates the epoch time of the base station 100 (for example, the serving cell of the terminal 200) that corresponds to the epoch time of the neighboring cell.

[0092] FIG. 8 is a diagram showing an example of the handover operation of the base station 100 and the terminal 200 in Method 1.

[0093] In the example shown in Fig. 8, gNB1 (e.g., base station 100) communicates with UEs in cell 1 formed by satellite 1, and gNB2 communicates with UEs in cell 2 formed by satellite 2. The UE (e.g., terminal 200) shown in Fig. 8 is connected to gNB1.

[0094] For example, during handover, gNB1, which is the base station from which the handover originates (source base station), sends a handover request (HANDOVER REQUEST) to gNB2, which is the base station to which the handover is directed (target base station) (process (1) shown in Figure 8).

[0095] The source base station gNB1 receives a handover request response (HANDOVER REQUEST ACKNOWLEDGE) from the target base station gNB2 (process (2) shown in Figure 8).

[0096] The handover request response may include, for example, system information used to receive and access signals from the target base station (or target cell).

[0097] Furthermore, the handover request response may include, for example, as shown in FIG. 8 , satellite ephemeris information, common TA parameters, and information regarding epoch time for satellite 2 forming the target cell (cell 2). Here, the epoch time may be expressed by an SFN and a subframe number. For example, in the handover request response, the source base station (gNB1) may be notified of an epoch time value based on an SFN and a subframe number based on the timing of the target cell (e.g., cell 2). Furthermore, the reference point of the epoch time may be set to a point where the uplink signal of the target cell is synchronized (e.g., an uplink synchronization reference point).

[0098] In the example shown in Fig. 8, SFN 25 and subframe 0 based on the timing of the target cell (cell 2) are notified to the source base station (gNB1) as the epoch time. Also, in the example shown in Fig. 8, the reference point for the epoch time of the target cell may be the transmission point of the target base station (gNB2) or may be satellite 2 that forms the target cell (cell 2).

[0099] The source base station (gNB1) notifies the UE in cell 1 of control information such as the system information of the target cell, satellite ephemeris information, common TA parameters, epoch time, and expiration date acquired from the target base station (gNB2) (process (3) shown in FIG. 8 ). This information may be notified to the UE by, for example, an RRC message (RRC reconfiguration message) or an SIB.

[0100] Here, in method 1, the source base station (gNB1) converts (or rewrites) the SFN and subframe number based on the timing of the target cell (cell 2) for the epoch time into the SFN and subframe number based on the timing of the source cell (cell 1) of the source base station (gNB1). In the example shown in Fig. 8, the source base station (gNB1) converts SFN 25, subframe 0 of the target cell indicated in the information related to the epoch time into SFN 10, subframe 3 of the source cell, which have the same timing as SFN 25, subframe 0 of the target cell. The source base station (gNB1) may notify the UE in cell 1 of information related to the epoch time indicating the converted SFN 10, subframe 3.

[0101] In addition, the information notified from the source base station (gNB1) to the UE may include, for example, information regarding handover conditions.

[0102] In Figure 8, for example, when the UE receives the above information via an RRC message or SIB from the gNB1 to which the UE is connected, the UE determines (or evaluates or monitors) whether the notified handover condition is satisfied. For example, to determine whether the handover condition is satisfied or to confirm after the handover condition is satisfied, the UE may perform reception quality measurement using the SSB of the target cell.

[0103] Furthermore, for example, when the carrier frequency of the connected cell and the adjacent cell differ, the UE may open the receiving window at the arrival timing of the SSB signal of the target cell to be measured and receive the signal of the target cell. Furthermore, the UE may close the receiving window at a timing different from the arrival timing of the SSB signal of the target cell to be measured and stop receiving the signal of the target cell. In this case, the UE may estimate a propagation delay using satellite ephemeris information and common TA parameters of the target cell and adjust the timing of the receiving window based on the estimated propagation delay.

[0104] Furthermore, the UE may access the target cell (e.g., transmit a RACH) to execute handover (e.g., process (4) shown in FIG. 8 ). At this time, the UE may estimate propagation delays (service link delay and feeder link delay) using satellite ephemeris information and common TA parameters of the target cell, and transmit uplink RACH and the like (e.g., adjust transmission timing) based on the estimated propagation delay.

[0105] At this time, for example, the UE may interpret the epoch time of the target cell based on the SFN and subframe timing of the cell to which the UE is connected (the source cell). In the example shown in Fig. 8, the UE interprets the epoch time as SFN 10, subframe 3 based on the SFN and subframe timing of gNB1, which is the source cell. Then, the UE may calculate the satellite position from the satellite ephemeris information based on the interpreted epoch time, and calculate the feeder link delay amount (e.g., a common TA value) from the common TA parameter.

[0106] 8, the reference point of the epoch time of the target cell is the point where the uplink signal of the target cell is synchronized (uplink synchronization reference point). The UE may estimate the real-time epoch time based on, for example, the reception timing of the signal from the target cell and the estimated propagation delay between the UE and the reference point.

[0107] In this way, in method 1, base station 100 converts the epoch time of a neighboring cell based on the SFN and subframe used in base station 100, and notifies terminal 200. As a result, in method 1, terminal 200 can correctly identify the timing of the epoch time of the neighboring cell even when it is unable to receive a signal from the neighboring cell (for example, a signal including the SFN of the neighboring cell, such as an MIB or PBCH).

[0108] Note that, in method 1, a case has been described in which the epoch time of a neighboring cell is converted based on the SFN and subframes used in base station 100, but the present invention is not limited to this. For example, base station 100 may notify terminal 200 of the epoch time of a neighboring cell generated based on the SFN and subframes used in base station 100. Alternatively, base station 100 may notify terminal 200 of the epoch time of a neighboring cell generated in an external device (e.g., a core network or another control device) based on the SFN and subframes used in base station 100. In this case, information or parameters may also be generated for satellite ephemeris and common TA parameters that match the epoch time based on the SFN and subframes used in base station 100.

[0109] <Method 2> In method 2, the base station 100 notifies the terminal 200 of, for example, the epoch time (e.g., SFN and subframe number) of the neighboring cell, as well as a value related to the difference between the SFN and subframe number corresponding to the epoch time in the base station 100 and the SFN and subframe number corresponding to the epoch time in the neighboring cell. For example, the control information related to the epoch time notified from the base station 100 to the terminal 200 indicates the difference between the epoch time of the neighboring cell and the epoch time of the base station 100 (e.g., the serving cell of the terminal 200).

[0110] FIG. 9 is a diagram showing an example of the handover operation of the base station 100 and the terminal 200 in Method 2.

[0111] In the example shown in Fig. 9, gNB1 (e.g., base station 100) communicates with UEs in cell 1 formed by satellite 1, and gNB2 communicates with UEs in cell 2 formed by satellite 2. The UE (e.g., terminal 200) shown in Fig. 9 is connected to gNB1.

[0112] 9 may be the same as those in Method 1 (FIG. 8). Also, the reference point of the epoch time of the target cell may be set to a point where the uplink signal of the target cell is synchronized (for example, an uplink synchronization reference point), as in Method 1.

[0113] As in method 1, the source base station (gNB1) notifies the UE (terminal 200) in cell 1 of control information such as the system information of the target cell, satellite ephemeris information, common TA parameters, epoch time, and expiration date acquired from the target base station (gNB2) (process (3) shown in FIG. 9 ). This information may be notified to the UE by, for example, an RRC message (RRC reconfiguration message) or an SIB.

[0114] Here, in method 2, the source base station (gNB1) may determine information (e.g., referred to as "SFN difference") regarding the difference (or difference) in SFN between the target cell (cell 2) and the source cell (cell 1) for an epoch time. The source base station may obtain information regarding the SFN difference, for example, by exchanging information with the target base station. In the example shown in FIG. 9, the source base station (gNB1) may generate an SFN difference indicating 15, which is the difference between the SFN of 25 of the target cell and the SFN of 10 of the source cell at the same time. The source base station (gNB1) may notify the UE in cell 1 of the generated information regarding the SFN difference.

[0115] 9, for example, when the UE receives the above information via an RRC message or SIB from the gNB1 to which the UE is connected, the UE determines (or evaluates or monitors) whether the notified handover condition is satisfied. For example, to determine whether the handover condition is satisfied or to confirm after the handover condition is satisfied, the UE may perform reception quality measurement using the SSB of the target cell.

[0116] Furthermore, the UE may access the target cell (e.g., transmit a RACH) to execute handover (e.g., process (4) shown in Fig. 9 ). At this time, the UE may estimate propagation delays (service link delay and feeder link delay) using satellite ephemeris information and common TA parameters of the target cell, and transmit uplink RACH and the like (e.g., adjust transmission timing) based on the estimated propagation delay.

[0117] For example, the UE may interpret the time obtained by subtracting (or adding) an SFN difference from the epoch time notified by the source base station (gNB1) based on the SFN and subframe timing used in gNB1 (the source cell) to which the UE is connected as the epoch time of a neighboring cell (e.g., a target cell). In the example shown in Fig. 9, the UE may interpret the timing of SFN 10, obtained by subtracting SFN difference 15 from SFN 25 indicated in the epoch time notified by gNB1 in the source cell, as the timing of SFN 25 in the neighboring cell. Then, the terminal 200 may calculate a satellite position from satellite ephemeris information based on the interpreted epoch time, and calculate a feeder link delay amount (e.g., a common TA value) from a common TA parameter.

[0118] In addition, in FIG. 9 , the reference point of the epoch time of the target cell is the point where the uplink signal of the target cell is synchronized (uplink synchronization reference point), so the UE may estimate the real-time epoch time based on the reception timing of the signal from the target cell and the estimated propagation delay between the UE and the reference point.

[0119] The UE may use the calculated information to adjust the timing of the reception window for measuring the quality of the target cell, or adjust the timing when accessing the target cell when performing handover.

[0120] In this way, in method 2, base station 100 notifies terminal 200 of the epoch time of the neighboring cell as well as the difference in SFN between the neighboring cell and the cell of base station 100. As a result, in method 2, even if terminal 200 cannot receive a signal from the neighboring cell (for example, a signal including the SFN of the neighboring cell, such as MIB and PBCH), it can identify (or derive) the timing of the SFN of the neighboring cell and correctly identify the epoch time of the neighboring cell.

[0121] Note that information regarding the SFN difference is not limited to notification at the time of handover, and may be separately notified to terminal 200 by SIB or RRC control information.

[0122] In addition, in the example of Figure 9, we have described a case where base station 100 notifies terminal 200 of information regarding the difference in SFN, but in addition to the difference in SFN, information regarding the difference in subframe numbers between the source cell and the target cell may also be notified to terminal 200.

[0123] Methods 1 and 2 have been described above.

[0124] For example, information about the SFN is reported to terminal 200 by at least one of MIB and PBCH (e.g., sometimes referred to as "MIB / PBCH") broadcast in each cell. For example, when terminal 200 is located near a neighboring cell (e.g., a target cell), the reception quality (e.g., SNR: Signal to Noise Ratio) of the signal from the neighboring cell is good, and terminal 200 is likely to be able to receive the MIB / PBCH of the neighboring cell and acquire the SFN of the neighboring cell. On the other hand, when terminal 200 is located far from the neighboring cell, the SNR of the signal from the neighboring cell is poor, and terminal 200 is likely to be unable to receive the MIB / PBCH and acquire the SFN of the neighboring cell. For example, in the case of a conditional handover, terminal 200 receives information about the neighboring cell (e.g., including the epoch time of the neighboring cell) from base station 100 before the actual timing of handover. Therefore, at a time before the actual timing of handover, terminal 200 is likely to be located far away from the neighboring cell, and is likely to be unable to receive the MIB / PBCH of the neighboring cell (e.g., information regarding the SFN of the neighboring cell).

[0125] In this embodiment, the terminal 200 receives, for example, control information for specifying an epoch time (e.g., a reference time) in transmission timing control (including, for example, determination of a satellite position or calculation of a feeder link delay time) of an uplink signal (e.g., a RACH) to an adjacent cell in a cell to which the terminal 200 is connected, and controls the transmission timing based on the received control information.

[0126] For example, terminal 200 can correctly interpret the epoch time of a neighboring cell included in control information (e.g., an RRC Reconfiguration message or an SIB) received from base station 100, which is the serving cell, based on the timing of the SFN and subframe in the serving cell. Therefore, for example, terminal 200 can improve the accuracy of estimating the satellite position and the feeder link delay amount in the neighboring cell even if it does not receive information about the SFN and / or subframe of the neighboring cell via the MIB / PBCH or SIB of the neighboring cell.

[0127] Furthermore, even when the terminal 200 does not receive the MIB / PBCH or SIB of the neighboring cell, for example, when the terminal 200 is located far from the neighboring cell, the terminal 200 can correctly interpret the epoch time of the neighboring cell, and therefore can correctly determine the expiration date of the notified information regarding the neighboring cell.

[0128] Furthermore, in this embodiment, as shown in Figures 8 and 9, information for a neighboring (or target) cell (e.g., including satellite ephemeris, common TA parameters, and epoch time) is information generated in the neighboring (or target) base station. In this case, the epoch time reference point may be set to a point at which the uplink signals of the neighboring cells are synchronized. This allows the base station 100 to easily generate information on the satellite ephemeris and common TA parameters of the neighboring cells based on the epoch time reference point. Furthermore, the terminal 200, for example, identifies the epoch time reference point, and thereby estimates the real-time epoch time based on the reception timing of a signal from the neighboring cell and the estimated propagation delay between the terminal 200 and the reference point when accessing the neighboring (target) cell, thereby appropriately calculating the TA value of the transmission timing of the uplink signal.

[0129] Therefore, according to this embodiment, it is possible to improve the accuracy of the transmission timing control of the uplink signal.

[0130] If handover is not triggered within a validity period from the epoch time interpreted by the above-described method, terminal 200 may determine that handover has failed and notify base station 100. After determining that handover has failed, terminal 200 may again receive from base station 100 an RRCReconfiguration message or SIB updated to new parameters.

[0131] Second Embodiment The configurations of base station 100 and terminal 200 according to this embodiment may be the same as those in the first embodiment, for example.

[0132] In this embodiment, for example, base station 100 does not need to notify terminal 200 performing conditional handover within the cell of base station 100 of satellite ephemeris information, common TA parameters, and information regarding epoch time of the target cell.

[0133] For example, the base station 100 (e.g., the control unit 102) may notify the terminal 200 performing a normal handover of the satellite ephemeris information, common TA parameters, and epoch time information of the target cell by using an RRC reconfiguration message at the time of handover. On the other hand, the base station 100 may not notify the terminal 200 performing a conditional handover of the satellite ephemeris information, common TA parameters, and epoch time information of the target cell. In addition, at this time, the base station 100 may not acquire this information from the target base station.

[0134] In addition, in this embodiment, for example, terminal 200 may receive the satellite ephemeris information, common TA parameters, and epoch time information of the target cell from the target cell, without receiving them from the cell to which terminal 200 is connected (e.g., the source cell or the serving cell).

[0135] For example, when performing a conditional handover, terminal 200 (e.g., data reception processing unit 203) may receive information about the NTN (e.g., SIB) from the target cell and acquire satellite ephemeris information, common TA parameters, and information about the epoch time of the target cell before accessing the target cell (e.g., transmitting a RACH). When performing a conditional handover, terminal 200 does not need to receive information about the NTN of the target cell (e.g., information about the epoch time) from a cell to which terminal 200 connects (e.g., a serving cell or a source cell).

[0136] For example, terminal 200 accesses the target cell (for example, transmits a RACH) after acquiring satellite ephemeris information, common TA parameters, and epoch time information of the target cell included in the SIB. At this time, terminal 200 may set the reference point of the epoch time of the target cell (for example, a neighboring cell) as the synchronization point of the uplink in the target cell. Note that the reference point of the epoch time of the target cell may be specified in advance in, for example, a specification (for example, a standard). Alternatively, information regarding the reference point of the epoch time of the target cell (for example, indicating the point at which the uplink signal is synchronized in the target cell) may be notified to terminal 200.

[0137] Furthermore, for example, if a conditional handover is not performed, the terminal 200 does not need to receive information regarding the NTN from the target cell.

[0138] Note that terminal 200 may receive information about the NTN of the target cell before RACH processing to the target cell in handover from the source cell to the target cell. For example, terminal 200 may receive SIB related to the NTN of the target cell between when a handover condition is satisfied and handover is triggered and when RACH transmission is performed.

[0139] Furthermore, when accessing a target cell (e.g., transmitting a RACH), the terminal 200 (e.g., the timing adjustment unit 205) may acquire satellite ephemeris information, common TA parameters, and epoch time information contained in information about the NTN (e.g., SIB) received from the target cell, and then perform timing adjustment based on equation (2).

[0140] FIG. 10 is a diagram showing an example of handover operation of base station 100 and terminal 200 in this embodiment.

[0141] In the example shown in Figure 10, gNB1 (e.g., base station 100) communicates with UEs in cell 1 formed by satellite 1, and gNB2 communicates with UEs in cell 2 formed by satellite 2.

[0142] A UE (e.g., terminal 200) shown in Figure 10 is connected to gNB1. Also, in Figure 10, the UE performs conditional handover. As shown in Figure 10, for example, the UE moves from a position within cell 1 where it cannot receive the MIB / PBCH or SIB (e.g., SIB related to NTN) of cell 2 to a position where it can receive the MIB / PBCH or SIB of cell 2.

[0143] For example, during a conditional handover, the source base station gNB1 sends a handover request (HANDOVER REQUEST) to the target base station gNB2 (process (1) shown in Figure 10).

[0144] The source base station gNB1 receives a handover request response (HANDOVER REQUEST ACKNOWLEDGE) from the target base station gNB2 (process (2) shown in Figure 8).

[0145] The handover request response may include, for example, system information used to receive and access signals from the target base station (or target cell).

[0146] Here, when a conditional handover is performed, the handover request response does not need to include information regarding satellite ephemeris information, common TA parameters, and epoch time for satellite 2 that forms the target cell (cell 2).

[0147] The source base station (gNB1) notifies the UE (terminal 200) in cell 1 of the system information of the target cell acquired from the target base station (gNB2) (process (3) shown in FIG. 10 ). This information may be notified to the UE by, for example, an RRC message (RRC reconfiguration message) or an SIB. In this way, the UE performing conditional handover in cell 1 does not acquire, from gNB1, information on the satellite ephemeris information, common TA parameters, and epoch time of the target cell (cell 2).

[0148] In Figure 10, when a UE receives system information, for example, via an RRC message or SIB from the gNB1 to which the UE is connected, it may determine (or evaluate, monitor) whether the handover conditions are met, as in embodiment 1.

[0149] When the handover condition is satisfied, the UE may access the target cell (for example, transmit a RACH) to execute handover (for example, process (4) shown in FIG. 10 ). At this time, the UE may acquire information on the satellite ephemeris information, common TA parameters, and epoch time of the target cell by, for example, receiving an MIB or SIB related to the NTN of the target cell from the target cell before transmitting the RACH. For example, when the terminal 200 cannot receive an MIB (for example, including the SFN of the target cell) or an SIB related to the NTN of the target cell, the terminal 200 does not acquire information on the satellite ephemeris information, common TA parameters, and epoch time of the target cell.

[0150] The UE may then estimate propagation delay (service link delay and feeder link delay) using the satellite ephemeris information of the target cell and the common TA parameters, and transmit uplink RACH, etc. (e.g., adjust the transmission timing) based on the estimated propagation delay.

[0151] At this time, the UE may interpret the epoch time of the target cell based on the SFN and subframe timing of the target cell. In the example shown in Fig. 10, the UE interprets the epoch time of the target cell as SFN 25, subframe 0 based on the SFN and subframe timing of the target cell gNB2. Then, the UE may calculate the satellite position from the satellite ephemeris information based on the interpreted epoch time, and calculate the feeder link delay amount (e.g., a common TA value) from the common TA parameter.

[0152] 10, the reference point of the epoch time of the target cell is the point where the uplink signal of the target cell is synchronized (uplink synchronization reference point). The UE may estimate the real-time epoch time based on, for example, the reception timing of the signal from the target cell and the estimated propagation delay between the UE and the reference point.

[0153] As described above, in the present embodiment, the terminal 200 receives, for example, control information from a neighboring cell in a cell to which the terminal 200 is connected, for specifying an epoch time (e.g., a reference time) in transmission timing control (including, for example, determination of a satellite position or calculation of a delay time of a feeder link) of an uplink signal (e.g., a RACH) to the neighboring cell, and controls the transmission timing based on the received control information.

[0154] The base station 100 (e.g., source base station) does not notify the terminal 200 of the satellite ephemeris information, common TA parameters, and epoch time information of the target cell, which may be unable to receive MIB information from the target cell of the conditional handover (e.g., unable to acquire the SFN of the target cell) and therefore unable to correctly interpret the epoch time of the target cell. This makes it possible to reduce the amount of information to be notified, for example, the control overhead.

[0155] Furthermore, when terminal 200 approaches the target cell, terminal 200 acquires satellite ephemeris information, common TA parameters, and epoch time information included in the SIB of the target cell. In this case, terminal 200 can acquire the SFN of the target cell from, for example, MIB information from the target cell, and can therefore correctly interpret the epoch time of the target cell.

[0156] Furthermore, in this embodiment, information for the neighboring (or target) cell (including, for example, satellite ephemeris, common TA parameters, and epoch time) is information generated in the neighboring (or target) base station. In this case, the reference point of the epoch time may be set to a point at which the uplink signal of the target cell (for example, the neighboring cell) is synchronized. For example, by identifying the reference point of the epoch time, the terminal 200 can appropriately calculate the TA value of the transmission timing of the uplink signal by estimating the real-time epoch time based on the reception timing of the signal from the target cell and the estimated propagation delay amount between the terminal 200 and the reference point when accessing the target cell.

[0157] Furthermore, terminal 200 only needs to acquire satellite ephemeris information, common TA parameters, and epoch time information of the target cell before accessing the target cell. Therefore, terminal 200 is likely to have sufficient time from receiving notification of conditional handover until accessing the target cell, and since the execution timing of handover can be estimated from the handover conditions, terminal 200 can receive the SIB of the target cell with ample time to spare.

[0158] Therefore, according to this embodiment, it is possible to improve the accuracy of the transmission timing control of the uplink signal.

[0159] Third Embodiment The configurations of base station 100 and terminal 200 according to this embodiment may be the same as those in the first embodiment, for example.

[0160] In this embodiment, for example, base station 100 may notify terminal 200 of information regarding the epoch time based on the SFN and subframe number of the target cell, which is acquired from the target cell, as is.

[0161] For example, the base station 100 (e.g., the control unit 102) may notify the terminal 200 performing a normal handover or a conditional handover of the satellite ephemeris information, the common TA parameters, and the epoch time information of the target cell by using an RRC reconfiguration message. Here, the epoch time may be based on the SFN and the subframe number of the target cell.

[0162] Furthermore, for example, the reference point of the epoch time may be set to a synchronization point of the uplink in the target cell. Note that the reference point of the epoch time of the target cell may be, for example, predefined in a specification (e.g., a standard). Alternatively, information regarding the reference point of the epoch time of the target cell (e.g., indicating that it is a point at which the uplink signal is synchronized in the target cell) may be notified to terminal 200.

[0163] Also, in this embodiment, for example, terminal 200 (e.g., data reception processing unit 203) receives an RRCReconfiguration message from base station 100 (e.g., serving cell or source cell), and acquires satellite ephemeris information, common TA parameters, and epoch time information of the target cell.

[0164] Furthermore, terminal 200 may acquire, for example, information regarding the SFN of the target cell from the target cell (for example, a neighboring cell). The information regarding the SFN of the target cell may be notified, for example, by the MIB / PBCH from the target cell. For example, terminal 200 may acquire the SFN of the target cell when it is located close to the target cell (for example, when the SNR of the signal from the target cell is sufficient).

[0165] Furthermore, the terminal 200 may, for example, interpret the epoch time at the time of acquiring the SFN of the target cell, and identify the satellite position and calculate the propagation delay amount (e.g., TA value) from the satellite ephemeris information and common TA parameters notified from the source cell.

[0166] Furthermore, the terminal 200 (e.g., the timing adjustment unit 205), for example, when transmitting a RACH to a target cell, may perform timing adjustment based on equation (2) based on the satellite ephemeris information, common TA parameters, and epoch time information of the target cell.

[0167] In this case, since the reference point of the epoch time is the point at which the uplink signal of the target cell is synchronized, the terminal 200 may estimate the real-time epoch time based on the reception timing of the signal from the target cell and the estimated propagation delay between the terminal 200 and the reference point.

[0168] In this way, terminal 200 receives control information regarding the NTN of the target cell (e.g., including the epoch time of the target cell) from the cell to which terminal 200 is connected (e.g., the source cell or serving cell), and receives information regarding the SFN of the target cell from the target cell.

[0169] FIG. 11 is a diagram showing an example of handover operation of base station 100 and terminal 200 in this embodiment.

[0170] In the example shown in Figure 11, gNB1 (e.g., base station 100) communicates with UEs in cell 1 formed by satellite 1, and gNB2 (e.g., base station 100) communicates with UEs in cell 2 formed by satellite 2.

[0171] A UE (e.g., terminal 200) shown in Fig. 11 is connected to gNB 1. As shown in Fig. 11, for example, within cell 1, the UE moves from a position where it cannot receive the MIB / PBCH or SIB (e.g., SIB related to NTN) of cell 2 to a position where it can receive the SIB / PBCH or SIB of cell 2.

[0172] 11, the process (1) and the process (2) may be the same as those in the first embodiment. The reference point of the epoch time may be set to a point where the uplink signal of the target cell is synchronized (for example, an uplink synchronization reference point).

[0173] The source base station (gNB1) notifies the UE in cell 1 of the system information, satellite ephemeris information, common TA parameters, and epoch time information of the target cell acquired from the target base station (gNB2) (process (3) shown in FIG. 11 ). This information may be notified to the UE by, for example, an RRC message (RRC reconfiguration message) or an SIB.

[0174] In Figure 11, for example, when the UE receives an RRC message or SIB from the gNB1 to which the UE is connected, it may determine (or evaluate, monitor) whether the handover conditions are met, as in embodiment 1.

[0175] Here, if the UE does not receive the MIB / PBCH (e.g., including the SFN of the target cell) from the target cell (cell 2), the UE does not need to interpret the epoch time of the target cell received from the source cell (cell 1). Then, for example, if the terminal 200 approaches the target cell and receives the MIB / PBCH (e.g., including the SFN of the target cell) from the target cell (cell 2), the terminal 200 may interpret the epoch time of the target cell received from the source cell (cell 1).

[0176] In this way, the UE receives the target cell's satellite ephemeris information, common TA parameters and epoch time information from the source base station (or source cell), and receives the SFN information for interpreting the epoch time from the target base station (or target cell).

[0177] Then, the UE may calculate the satellite position from the satellite ephemeris information based on the interpreted epoch time, and calculate the feeder link delay amount (for example, a common TA value) from the common TA parameter.

[0178] For example, information regarding the SFN is reported to terminal 200 via the MIB / PBCH broadcast in each cell. For example, when terminal 200 is located near a neighboring cell (e.g., a target cell), the reception quality (e.g., SNR) of the signal from the neighboring cell is good, and terminal 200 is likely to be able to receive the MIB / PBCH of the neighboring cell and acquire the SFN of the neighboring cell. On the other hand, when terminal 200 is located far from the neighboring cell, the SNR of the signal from the neighboring cell is poor, and terminal 200 may not be able to receive the MIB / PBCH and acquire the SFN of the neighboring cell. For example, in the case of a conditional handover, terminal 200 receives information regarding the neighboring cell (e.g., including the epoch time of the neighboring cell) from base station 100 before the actual timing of handover. Therefore, at a time before the actual timing of handover, terminal 200 is likely to be located far from the neighboring cell and may not be able to receive the MIB / PBCH of the neighboring cell (e.g., information regarding the SFN of the neighboring cell). In this case, terminal 200 cannot correctly interpret the epoch time information based on the SFN of the target cell.

[0179] In contrast, in this embodiment, terminal 200 receives, from the currently connected cell (source cell), satellite ephemeris information of the target cell, common TA parameters, and epoch time information based on the SFN of the target cell. Furthermore, when terminal 200 is located close to the target cell, it receives the MIB / PBCH of the target cell from the target cell and acquires SFN information. In this way, in this embodiment, terminal 200 interprets epoch time information notified from the source cell after acquiring the SFN information of the target cell. This allows terminal 200 to correctly interpret (or derive) the epoch time based on the SFN of the target cell and appropriately estimate satellite position information and feeder link delay time.

[0180] Furthermore, in this embodiment, information for the neighboring (or target) cell (including, for example, satellite ephemeris, common TA parameters, and epoch time) is information generated in the neighboring (or target) base station. In this case, the reference point of the epoch time may be set to a point at which the uplink signals of the neighboring cells are synchronized. For example, by identifying the reference point of the epoch time, the terminal 200 can appropriately calculate the TA value of the transmission timing of the uplink signal by estimating the real-time epoch time based on the reception timing of the signal from the target cell and the estimated propagation delay amount between the terminal 200 and the reference point when accessing the target cell.

[0181] Furthermore, terminal 200 only needs to acquire satellite ephemeris information, common TA parameters, and epoch time information of the target cell before accessing the target cell. Therefore, there is a high possibility that there will be sufficient time between when terminal 200 receives notification of a conditional handover and when it accesses the target cell, and the execution timing of handover can be estimated from the handover conditions. Therefore, terminal 200 can receive the MIB of the target cell with ample time to perform timing adjustment for RACH transmission (for example, calculation of a TA value).

[0182] Note that base station 100 may notify terminal 200 of the satellite ephemeris information, common TA parameters, and epoch time information of the target cell at multiple timings.

[0183] For example, in NR, information related to the SFN is 10-bit information, and takes values ​​ranging from 0 to 1023. Therefore, the SFN has one cycle of 1024 frames (e.g., referred to as an "SFN cycle"), and the SFN is reset to 0 at each SFN cycle. For example, since one frame is 10 ms, the SFN is reset at each 10.24 seconds. For this reason, for example, as shown in FIG. 12 , when terminal 200 receives the MIB / PBCH of a neighboring cell (e.g., a target cell) and acquires (e.g., reads) the SFN of the neighboring cell, it may not be possible to determine which SFN cycle's SFN and subframe number correspond to the epoch time previously received.

[0184] 12 , for example, terminal 200 acquires the epoch time of the target cell during SFN cycle 1, and acquires the SFN of the target cell during SFN cycle 2. In this case, terminal 200 cannot determine whether the SFN and subframe number indicating the epoch time of the target cell correspond to SFN cycle 2, SFN cycle 1, or an SFN cycle earlier than SFN cycle 1.

[0185] Therefore, for example, base station 100 may notify terminal 200 of the satellite ephemeris information, common TA parameters, and epoch time information of the target cell at least every SFN cycle (for example, 10.24 seconds) as shown in Fig. 13. The satellite ephemeris information, common TA parameters, and epoch time information of the target cell may be notified to terminal 200 by, for example, an RRC reconfiguration message. Terminal 200 may receive the satellite ephemeris information, common TA parameters, and epoch time information of the target cell at least every SFN cycle, for example.

[0186] Here, the satellite ephemeris information, common TA parameters, and epoch time information of the target cell may be updated to match the epoch time expressed by the most recent SFN. For example, the information notified in SFN cycle 1 may be information based on the SFN of SFN cycle 1, and the information notified in SFN cycle 2 may be information based on the SFN of SFN cycle 2.

[0187] Terminal 200 receives, for example, satellite ephemeris information of the target cell, common TA parameters, and epoch time information via an RRC Reconfiguration message at multiple times. At this time, terminal 200 may determine (or assume) that the SFN indicated in the epoch time is an SFN in the same SFN cycle as the time at which the RRC Reconfiguration message is received. Alternatively, terminal 200 may determine (or assume) that the SFN indicated in the epoch time is the SFN closest to the time at which the RRC Reconfiguration message is received.

[0188] As a result, at the time when terminal 200 receives the MIB of the target cell and acquires the SFN, it can uniquely identify the SFN indicated in the epoch time and correctly interpret the epoch time.

[0189] Although an example has been described in which the satellite ephemeris information, common TA parameters, and epoch time information of the target cell are notified to terminal 200 by an RRCReconfiguration message, the present invention is not limited to this and may be reported by an SIB. In this case, terminal 200 may receive the corresponding SIB at predetermined intervals (for example, at intervals of an SFN cycle).

[0190] (Embodiment 4) The configurations of the base station 100 and the terminal 200 according to this embodiment may be the same as, for example, those of Embodiment 1. In addition to the base station 100 and the terminal 200, the communication system according to this embodiment may include an NTN control device (also referred to as an NTN control center, for example) 300.

[0191] The NTN control device 300 controls, for example, multiple base stations 100 and satellites. For example, the NTN control device 300 may generate at least one of satellite ephemeris and common TA parameters corresponding to each of the multiple base stations 100 (or satellites).

[0192] The NTN control device 300 may, for example, notify each base station 100 of at least one of the assistance information (e.g., satellite ephemeris and common TA parameters) notified from each base station 100 to the terminal 200. For example, the base station 100 (e.g., the control unit 102) receives assistance information (e.g., including satellite ephemeris and common TA parameters) related to the satellites used by each base station 100 from the NTN control device 300. Then, the base station 100 may notify the terminal 200 of the received information. Note that SIB or RRC control information may be used for notification to the terminal 200.

[0193] Here, the information transmitted from the NTN control device 300 to the base station 100 and the information notified from the base station 100 to the terminal 200 may include information regarding the cell (serving cell) configured by the base station 100 and information regarding a neighboring cell (or target cell) not configured by the base station 100.

[0194] Furthermore, the base station 100 (e.g., the control unit 102) may directly notify the terminal 200 of information including the satellite ephemeris and common TA parameters received from the NTN control device 300. In this case, the reference point of the epoch time may be set to a point set by the NTN control device 300 (e.g., a serving cell or a neighboring cell).

[0195] Alternatively, the base station 100 may, for example, estimate a satellite orbit, and based on the estimated satellite orbit, generate new information from information including satellite ephemeris and common TA parameters received from the NTN control device 300, and notify the terminal 200. In this case, the reference point of the epoch time may be set to the reference point of the base station 100 that generated the information, for example, the reference point of the serving cell for the terminal 200.

[0196] FIG. 14 is a diagram showing an example of the operation of the base station 100 (gNB), the terminal 200 (UE), and the NTN control device 300 (NTN control center) in this embodiment.

[0197] In the example shown in Fig. 14, gNB1 (e.g., base station 100) communicates with UEs in cell 1 formed by satellite 1, and gNB2 communicates with UEs in cell 2 formed by satellite 2. The UE (e.g., terminal 200) shown in Fig. 14 is connected to gNB1.

[0198] 14, for example, the NTN control device 300 acquires information about the satellite position and time from each satellite (e.g., satellite 1 and satellite 2). For communication used to acquire the information about the satellite position and time, a control line different from the communication line for NTN, such as a telemetry line, is assumed.

[0199] The NTN control device 300 may generate information (e.g., assistance information) about each satellite (e.g., satellite 1 and satellite 2), such as satellite ephemeris information and common TA parameters, based on, for example, information about the satellite position and time obtained from each satellite.

[0200] Then, the NTN control device 300 notifies, for example, each base station 100 (for example, gNB1 and gNB2) of the generated information. At this time, the NTN control device 300 may notify, for example, each base station 100 of information related to the satellite (or base station) that forms an adjacent cell in addition to information corresponding to that base station 100. In the example shown in FIG. 14, both information related to satellite 1 and information related to satellite 2 are notified to each of gNB1 and gNB2.

[0201] Each base station 100 notifies the terminal 200 (UE) of information about the satellite (for example, satellite ephemeris information and common TA parameters) received from the NTN control device 300. Furthermore, each base station 100 notifies the terminal 200 of information about epoch time, along with the information about the satellite. The information about epoch time may include, for example, information about the SFN and subframe notified as the epoch time, and information about a reference point for the epoch time.

[0202] Below, methods for setting information about epoch time (for example, method 1 and method 2) will be described.

[0203] <Method 1> In method 1, the base station 100 may notify the terminal 200 of the satellite ephemeris information and the common TA parameter information generated in the NTN control device 300 as is, for example.

[0204] In this case, information about the epoch time may be generated, for example, in the NTN control device 300. For example, the NTN control device 300 may set the SFN and subframe number to be notified as the epoch time, and the reference point for the epoch time.

[0205] For example, which cell (e.g., serving cell or neighboring cell) each of the SFN and subframe number and the reference point is based on may be specified in advance in a specification (e.g., a standard). Alternatively, information on the cell that is the reference for the SFN and subframe number (e.g., referred to as information on the SFN and subframe number) may be notified to base station 100, or information on the cell that is the reference for the reference point (e.g., referred to as information on the reference point) may be notified to base station 100.

[0206] For example, the information on the SFN and subframe may indicate which cell (e.g., a serving cell or a neighboring cell) the SFN and subframe number notified as epoch time are based on. Furthermore, for example, the information on the reference point may indicate which cell (e.g., a serving cell or a neighboring cell) the reference point of the epoch time is a synchronization point of an uplink signal in. The information on the SFN and subframe number notified as epoch time and the information on the reference point may include a cell ID as a parameter indicating which cell the information is based on, or may include a value indicating either the serving cell or the neighboring cell.

[0207] Base station 100 may notify terminal 200, for example, of satellite ephemeris, common TA parameters, and epoch time, as well as information on SFN and subframe number, and information on reference point. Each of the information on SFN and subframe number, and information on reference point may be notified to terminal 200 individually or as common information.

[0208] For example, terminal 200 may identify which cell the SFN and subframe number are based on based on information on the SFN and subframe number notified as the epoch time, and may identify which cell's reference point is the point with which the uplink signal is synchronized based on information on the reference point. Then, terminal 200 may interpret the epoch time based on the identified SFN and subframe number and the reference point, and calculate the TA value for uplink transmission.

[0209] In this way, in method 1, the SFN and subframe number notified as the epoch time, and information indicating which cell the reference point of the epoch time is based on, are notified to terminal 200. This allows terminal 200 to identify the SFN, subframe number, and reference point for the epoch time and appropriately interpret the epoch time, thereby appropriately deriving satellite position information and a common TA value and accurately calculating the TA value for uplink transmission.

[0210] <Method 2> In method 2, the base station 100 may, for example, use the satellite ephemeris information and common TA parameter information generated in the NTN control device 300 to newly generate (e.g., update) at least one of the satellite ephemeris information and the common TA parameter of the cell of the base station 100 (e.g., the serving cell) and the neighboring cell, and notify the generated information to the terminal 200.

[0211] For example, the base station 100 may estimate the satellite orbits for the satellite to which the base station 100 is connected (or used) and the satellite of an adjacent cell, and based on the estimated satellite orbits, newly generate at least one of the satellite ephemeris information and common TA parameter information for the cell of the base station 100 and the adjacent cell.

[0212] This allows the base station 100 to notify the terminal 200 of more accurate satellite ephemeris information and common TA parameter information based on, for example, the satellite orbits of the satellites that form each cell.

[0213] In this case, the information regarding the epoch time may be generated in, for example, the base station 100. For example, the base station 100 may set the epoch time (e.g., SFN and subframe) based on the SFN and subframe number of the cell formed by the base station 100. Furthermore, the base station 100 may set the reference point of the epoch time to a reference point corresponding to the base station 100 (or the cell formed by the base station 100). In this case, the information regarding the SFN and subframe number may indicate that the SFN and subframe number notified as the epoch time are based on the serving cell. Furthermore, for example, the information regarding the reference point may indicate whether the reference point of the epoch time is a synchronization point of the uplink signal in the serving cell.

[0214] Thus, for example, when information for a neighboring (or target) cell (e.g., including satellite ephemeris, common TA parameters, and epoch time) is generated in a device (e.g., base station 100 or NTN control device 300) different from the neighboring (or target) base station, the reference point for the epoch time may be set to the point at which the uplink signal of the serving cell is synchronized.

[0215] For example, when terminal 200 receives satellite ephemeris information, common TA parameter information, and epoch time information, it may determine that the SFN and subframe number information notified as the epoch time and that the reference point of the epoch time is based on the serving cell, interpret the epoch time, and calculate the TA value for uplink transmission.

[0216] Since the SFN and subframe number notified as the epoch time, and the reference point of the epoch time are set based on the serving cell, the terminal 200 can appropriately interpret the epoch time in the serving cell and appropriately derive the satellite position information and common TA value of the serving cell and neighboring cells, and can therefore accurately calculate the TA value during uplink transmission.

[0217] Furthermore, since the terminal 200 can interpret the epoch time without receiving signals from neighboring cells, for example, it can derive satellite position information and a common TA value in neighboring cells even in an environment where it cannot receive neighboring cell signals.

[0218] The NTN control device 300 may generate satellite ephemeris and notify each base station 100, and each base station may generate a common TA parameter. Also, for example, the epoch time for the satellite ephemeris information may be different from the epoch time for the common TA parameter.

[0219] Methods 1 and 2 have been described above.

[0220] As described above, in the present embodiment, base station 100 determines, in the serving cell, control information related to a reference point for epoch time in controlling the transmission timing of uplink signals to a neighboring cell (or a target cell) (e.g., information indicating which cell's uplink signal is a point with which synchronization is performed), and transmits the control information to terminal 200. Terminal 200 receives, in the serving cell, the control information related to the reference point for epoch time of the neighboring cell (or the target cell), and controls the transmission timing of uplink signals to the neighboring cell based on the control information.

[0221] This allows the terminal 200 to identify (or share) the reference point of the epoch time for the satellite ephemeris of the neighboring cell and the common TA parameters, thereby correctly interpreting the epoch time and improving the accuracy of estimating the satellite position using the satellite ephemeris for the neighboring cell and the delay amount of the feeder link using the common TA parameters.

[0222] Therefore, according to this embodiment, it is possible to improve the accuracy of the transmission timing control of the uplink signal.

[0223] Fifth Embodiment The configurations of base station 100 and terminal 200 according to this embodiment may be the same as those of the first embodiment, for example.

[0224] In this embodiment, for example, the epoch time for the satellite ephemeris information and common TA parameter information of the neighboring cell (or the target cell) may be expressed in absolute time (for example, in the format of the clock).

[0225] For example, the base station 100 (e.g., the control unit 102) generates the epoch time for the satellite ephemeris information and common TA parameter information of the base station 100 (e.g., the serving cell) as an SFN and a subframe number, similar to any of the first to fourth embodiments.

[0226] Meanwhile, the base station 100 generates epoch times for the satellite ephemeris information and common TA parameter information of neighboring cells or neighboring base stations as information in a time format, which may be, for example, absolute time, Coordinated Universal Time (UTC), or UNIX (registered trademark) time.

[0227] Furthermore, the base station 100 (e.g., the control unit 102) may broadcast time information to the terminal 200 that cannot use a GNSS function such as GPS. For example, the base station 100 may notify the terminal 200 of information including the relationship between the timing of an SFN and time (e.g., the start time of the SFN that transmits SIB9), such as SIB9 specified in 3GPP TS38.331.

[0228] For example, if the GNSS function is available, the terminal 200 acquires time information using the GNSS function. If the GNSS function is unavailable, the terminal 200 acquires time information by receiving SIB9, for example.

[0229] Then, when terminal 200 receives satellite ephemeris information for neighboring cells, common TA parameter information, and information on the epoch time corresponding thereto, terminal 200 interprets the epoch time as time information.

[0230] This allows the terminal 200 to appropriately interpret the epoch time for the satellite ephemeris information and common TA parameter information for neighboring cells notified by the base station 100, without being aware of which cell the epoch time is based on.

[0231] The embodiments of the present disclosure have been described above.

[0232] In each of the above-mentioned embodiments, examples of conditional handover have been described, but this is not limited to this, and a similar method can also be used when performing normal handover or when notifying neighboring cell information for cell selection.

[0233] Furthermore, in each of the above-described embodiments, different operations may be performed for handover and cell selection. For example, base station 100 may notify terminal 200 of an epoch time based on the SFN and subframe number of base station 100 (e.g., serving cell) and assistance information (satellite ephemeris, common TA parameters) as information about a neighboring cell to be used for cell selection or neighboring cell measurement, and may notify terminal 200 of an epoch time based on the SFN and subframe number of the target base station or target cell and assistance information (satellite ephemeris, common TA parameters) as information about a target cell to be used for handover. Furthermore, the reference point for the epoch time of the assistance information (satellite ephemeris, common TA parameters) of the neighboring cell to be used for cell selection or neighboring cell measurement may be the synchronization point of the uplink signal in the serving cell, and the reference point for the epoch time of the assistance information (satellite ephemeris, common TA parameters) of the target cell to be used for handover may be the synchronization point of the uplink signal in the target cell. In the case of cell selection or neighbor cell measurement, terminal 200 may be in a position where it cannot receive the MIB, PBCH, or SIB of the neighbor cell at the time of receiving this information from base station 100. Therefore, by notifying terminal 200 of the epoch time, satellite ephemeris, and common TA parameters based on the SFN and subframe number of the serving cell, terminal 200 can correctly interpret the epoch time information based on the SFN and subframe timing of the serving cell and can appropriately control the measurement window using the information on the satellite ephemeris and common TA parameters. Furthermore, during handover, terminal 200 is likely to be located near a neighbor cell.Therefore, by notifying terminal 200 of the epoch time, satellite ephemeris, and common TA parameters based on the SFN and subframe number of the target cell, terminal 200 can acquire the SFN and subframe information of the target cell from the MIB / PBCH of the target cell, and can therefore correctly interpret the epoch time information and access the target cell using the satellite ephemeris and common TA parameter information.

[0234] In addition, information about the neighboring cells for cell selection or neighboring cell measurement may be broadcast in an SIB, and information about the neighboring cells for handover may be notified to terminal 200 by RRC control information such as an RRC Reconfiguration message, for example.

[0235] In addition, as the satellite ephemeris information and common TA parameter information of the neighboring cell, the base station 100 may notify the terminal 200 of, for example, information regarding whether or not the information is the same as the satellite ephemeris information and common TA parameter information of the cell of the base station 100 (e.g., the serving cell).

[0236] In addition, the satellite ephemeris information and the common TA parameter information may be notified as "EpochTime" and "TAInfo", respectively, in the NTN-Config of SIB19, for example.

[0237] Furthermore, in each of the above-described embodiments, when information such as satellite ephemeris and common TA parameters is notified to terminal 200 by an SIB, the epoch time may be implicitly notified by the first (e.g., start) or last (e.g., end) subframe of the SI-window in which the SIB is transmitted. In this case, base station 100 notifies terminal 200, as neighbor cell information, the epoch time, satellite ephemeris, and common TA parameters based on the SFN and / or subframe timing of base station 100 (e.g., serving cell). Alternatively, when the epoch time, satellite ephemeris, and common TA parameters based on the SFN and / or subframe timing of base station 100 (e.g., serving cell) are notified to terminal 200, the epoch time may be implicitly notified by the first or last subframe of the SI-window in which the SIB is transmitted.

[0238] In each of the above-described embodiments, a cell may be an area defined by the received power of an SSB or a Channel State Information - Reference Signal (CSI-RS) transmitted by a base station (or a satellite), or may be an area defined by a geographical location. Also, the cell in each of the above-described embodiments may be replaced with a beam defined by an SSB.

[0239] In each of the above-described embodiments, satellite ephemeris information, which is information related to satellite positions, may be reported by system information or may be stored in advance by terminal 200. Furthermore, satellite ephemeris information may be updated when communication is possible. Furthermore, terminal 200 may identify satellite positions using information other than satellite ephemeris information.

[0240] In addition, in each of the above-described embodiments, the base station may be read as a "network."

[0241] In addition, in the above-described embodiments, the target cell during handover has been described as an example, but the target cell may be interpreted as a neighboring cell. Also, the neighboring cell may be interpreted as a cell different from the serving cell. Furthermore, one aspect of the present disclosure can be applied not only to handover but also to neighboring cell measurements for cell selection or cell reselection.

[0242] Furthermore, as neighboring cell information, satellite ephemeris and common TA parameters of neighboring cells may be broadcast by SIB, and terminal 200 may use this information during cell selection or cell reselection in the RRC_IDLE state. Furthermore, during handover in the RRC_CONNECTED state, terminal 200 may be notified of information indicating which neighboring cell information to use as target cell information by terminal-specific RRC control information. This makes it possible to reduce the amount of information notified to terminal 200 during handover.

[0243] Furthermore, in each of the above-described embodiments, terminal 200 may measure reception quality using other signals such as CSI-RS instead of SSB signals.

[0244] In addition, in each of the above-described embodiments, an example has been described in which GNSS such as GPS (for example, position detection using satellite signals) is used, but this is not limiting, and position detection may be performed using, for example, a terrestrial cellular base station, a Wi-Fi (registered trademark) signal or a Bluetooth (registered trademark) signal, an acceleration sensor, or a combination of these detection methods. Furthermore, altitude information may be obtained from a barometric pressure sensor, etc.

[0245] Furthermore, in the above-described embodiment, uplink transmission from terminal 200 to base station 100 has been described, but an example of the present disclosure is not limited to this and may be applied to data in a downlink from base station 100 to terminal 200 or a link (e.g., a sidelink) between terminals 200. Furthermore, in the above-described embodiment, transmission of a RACH signal has been described as an example of uplink transmission, but the transmission target is not limited to RACH and may be other signals or channels.

[0246] Furthermore, an embodiment of the present disclosure may be applied regardless of the type of satellite, such as a geostationary Earth orbit satellite (GEO), a medium Earth orbit satellite (MEO), a low Earth orbit satellite (LEO), or a high elliptical orbit satellite (HEO). Furthermore, an embodiment of the present disclosure may be applied to non-terrestrial communications, such as a high-altitude airborne satellite (HAPS) or a drone base station.

[0247] Furthermore, although the above-described embodiment has been described using an NTN environment (e.g., a satellite communication environment) as an example, the present disclosure is not limited thereto. The present disclosure may be applied to other communication environments (e.g., at least one terrestrial cellular environment of LTE and NR). For example, one embodiment of the present disclosure may be applied to terrestrial communications in an environment where the cell size is large and the propagation delay between the base station 100 and the terminal 200 is longer (e.g., above a threshold). Furthermore, the present disclosure may be applied to communications other than NTN in which handover or cell selection is applied.

[0248] In addition, in the above-described embodiment, the form of satellite communication may be a configuration in which the base station functions are located on a satellite (e.g., a "regenerative satellite"), or a configuration in which the base station functions are located on the ground and a satellite relays communication between the base station and a terminal (e.g., a "transparent satellite"). For example, in one embodiment of the present disclosure, the downlink and the uplink may be links between a terminal and a satellite, or links via a satellite.

[0249] Moreover, the various parameters in the above embodiments are merely examples, and other numerical values ​​may be used. For example, the SFN of the epoch time, the subframe number of the epoch time, the number of frames in one cycle of the SFN, and the number of cells (or the number of satellites) are not limited to the values ​​shown in the above examples. Furthermore, the reference point of the epoch time is not limited to either the gNB or the satellite, and may be another point.

[0250] Furthermore, the method of notifying the control information from the base station 100 to the terminal 200 is not limited to the above-mentioned example, and may be notified (or reported, indicated, or set) by at least one of system information such as MIB and SIB, RRC control information, MAC control information, and downlink control information (DCI), or may be set in advance in the terminal 200, or may be specified in advance in a standard.

[0251] The base station may be referred to as a gNodeB or a gNB, and the terminal may be referred to as a UE.

[0252] Time resource units such as system frames and subframes may be replaced with slots, time slots, minislots, frames, subframes, and the like.

[0253] Furthermore, the notation "... section" in the above-described embodiments may be replaced with other notations such as "... circuitry," "... device," "... unit," or "... module."

[0254] (Supplementary Note) Information indicating whether the terminal 200 supports the functions, operations, or processes described in the above-described embodiments 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.

[0255] The capability information may include an information element (IE) that individually indicates whether or not the terminal 200 supports at least one of the functions, operations, or processes described in the above-described embodiments. Alternatively, the capability information may include an information element that indicates whether or not the terminal 200 supports a combination of any two or more of the functions, operations, or processes described in the above-described embodiments.

[0256] For example, the base station 100 may determine (or decide or assume) the functions, operations, or processes that the terminal 200 that transmitted the capability information supports (or does not support) based on the capability information received from the terminal 200. The base station 100 may perform operations, processes, or controls according to the determination result based on the capability information. For example, the base station 100 may control communications for the NTN based on the capability information received from the terminal 200.

[0257] Note that the fact that terminal 200 does not support some of the functions, operations, or processes described in the above-described embodiments may be interpreted as meaning that such some of the functions, operations, or processes are restricted in terminal 200. For example, information or a request regarding such restrictions may be notified to base station 100.

[0258] Information regarding the capabilities or limitations of terminal 200 may, for example, be defined in a standard, or may be implicitly notified to base station 100 in association with information known at base station 100 or information transmitted to base station 100.

[0259] (Control Signal) In the present disclosure, a downlink control signal (or downlink control information) related to an embodiment of the present disclosure may be, for example, a signal (or information) transmitted in a Physical Downlink Control Channel (PDCCH) of a physical layer, or a signal (or information) transmitted in a Medium Access Control Control Element (MAC CE) or Radio Resource Control (RRC) of a higher layer. Furthermore, the signal (or information) is not limited to being notified by a downlink control signal, but may be predefined in a specification (or standard) or preconfigured in a base station and a terminal.

[0260] In the present disclosure, an uplink control signal (or uplink control information) related to an embodiment of the present disclosure may be, for example, a signal (or information) transmitted in a PUCCH of a physical layer, or a signal (or information) transmitted in a MAC CE or RRC of a higher layer. Furthermore, the signal (or information) is not limited to being notified by an uplink control signal, but may be predefined in a specification (or standard) or preconfigured in a base station and a terminal. Furthermore, the uplink control signal may be replaced with, for example, uplink control information (UCI), 1st stage sidelink control information (SCI), or 2nd stage SCI.

[0261] (Base Station) In an embodiment of the present disclosure, the base station may be a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a parent device, a gateway, or the like. In sidelink communication, a terminal may play the role of a base station. Instead of a base station, a relay device that relays communication between an upper node and a terminal may be used. Alternatively, a roadside unit may be used.

[0262] (Uplink / Downlink / Sidelink) An embodiment of the present disclosure may be applied to, for example, any of the uplink, downlink, and sidelink. For example, an embodiment of the present disclosure may be applied to a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), or a Physical Random Access Channel (PRACH) in the uplink, a Physical Downlink Shared Channel (PDSCH), a PDCCH, or a Physical Broadcast Channel (PBCH) in the downlink, or a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Control Channel (PSCCH), or a Physical Sidelink Broadcast Channel (PSBCH) in the sidelink.

[0263] The PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. The PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel. The PBCH and PSBCH are examples of a broadcast channel, and the PRACH is an example of a random access channel.

[0264] (Data Channel / Control Channel) An embodiment of the present disclosure may be applied to, for example, either a data channel or a control channel. For example, the channel in an embodiment of the present disclosure may be replaced with any of the data channels PDSCH, PUSCH, and PSSCH, or the control channels PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0265] (Reference Signal) In one embodiment of the present disclosure, a reference signal is, for example, a signal known by both a base station and a mobile station, and may also be called a Reference Signal (RS) or a pilot signal. The reference signal may be any of a Demodulation Reference Signal (DMRS), a Channel State Information - Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), or a Sounding Reference Signal (SRS).

[0266] (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 be, for example, a time resource unit such as a frame, a superframe, a subframe, a slot, a time slot subslot, a minislot, or a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier-Frequency Division Multiplexing (SC-FDMA) symbol, or another time resource unit. Furthermore, the number of symbols included in one slot is not limited to the number of symbols exemplified in the above-mentioned embodiment, and may be another number of symbols.

[0267] (Frequency Band) An embodiment of the present disclosure may be applied to either a licensed band or an unlicensed band.

[0268] (Communication) An 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 an 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.

[0269] An embodiment of the present disclosure may be applied to a terrestrial network, a non-terrestrial network (NTN) using a satellite or a high altitude pseudo satellite (HAPS), or a terrestrial network in which transmission delay is large compared to the symbol length or slot length, such as a network with a large cell size or an ultra-wideband transmission network.

[0270] (Antenna Port) In one embodiment of the present disclosure, an antenna port refers to a logical antenna (antenna group) consisting 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 consisting of multiple antennas. For example, the number of physical antennas that an antenna port is composed of is not specified, and the antenna port may be specified as the smallest unit by which a terminal station can transmit a reference signal. Furthermore, an antenna port may also be specified as the smallest unit by which a weighting of a precoding vector is multiplied.

[0271] 5G NR System Architecture and Protocol Stack 3GPP continues work on the next release of fifth-generation cellular technology (also referred to simply as "5G"), which includes the development of new radio access technology (NR) operating in the frequency range up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, allowing for the prototyping and commercial deployment of 5G NR-compliant devices (e.g., smartphones).

[0272] For example, the system architecture generally assumes a Next Generation - Radio Access Network (NG-RAN) comprising gNBs. The gNBs provide UE-side termination of NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols. The gNBs are connected to each other via an Xn interface. The gNBs are also connected to a Next Generation Core (NGC) via a Next Generation (NG) interface, more specifically to an Access and Mobility Management Function (AMF) (e.g., a specific core entity performing AMF) via an NG-C interface, and to a User Plane Function (UPF) (e.g., a specific core entity performing UPF) via an NG-U interface. The NG-RAN architecture is shown in Figure 15 (see, for example, 3GPP TS 38.300 v15.6.0, section 4).

[0273] The NR user plane protocol stack (see, for example, 3GPP TS 38.300, section 4.4.1) includes a PDCP (Packet Data Convergence Protocol (see, for example, TS 38.300, section 6.4)) sublayer, a RLC (Radio Link Control (see, for example, TS 38.300, section 6.3)) sublayer, and a MAC (Medium Access Control (see, for example, TS 38.300, section 6.2)) sublayer, which are terminated on the network side in the gNB. A new access stratum (AS) sublayer (SDAP: Service Data Adaptation Protocol) has also been introduced above PDCP (see, for example, 3GPP TS 38.300, section 6.5). A control plane protocol stack has also been defined for the NR (see, for example, TS 38.300, section 4.4.2). An overview of Layer 2 functions is described in Section 6 of TS 38.300. The functions of the PDCP sublayer, RLC sublayer, and MAC sublayer are listed in clauses 6.4, 6.3, and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in clause 7 of TS 38.300.

[0274] For example, the Medium-Access-Control layer handles logical channel multiplexing and scheduling and scheduling-related functions, including handling various numerologies.

[0275] For example, the physical layer (PHY) is responsible for coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. The physical layer also handles 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 specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels include the Physical Random Access Channel (PRACH), the Physical Uplink Shared Channel (PUSCH), and the Physical Uplink Control Channel (PUCCH) as uplink physical channels, and the Physical Downlink Shared Channel (PDSCH), the Physical Downlink Control Channel (PDCCH), and the Physical Broadcast Channel (PBCH) as downlink physical channels.

[0276] NR use cases / deployment scenarios 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 approximately three times higher than those offered by IMT-Advanced. On the other hand, URLLC imposes stricter requirements on ultra-low latency (0.5 ms for user plane latency in both UL and DL) and high reliability (1-10-5 within 1 ms). Finally, mMTC preferably requires high connection density (1,000,000 devices / km in urban environments).２ ), wide coverage in adverse environments, and extremely long battery life (15 years) for a low-cost device may be desired.

[0277] Therefore, OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not be valid for another use case. For example, low-latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also referred to 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 accordingly to maintain similar CP overhead. NR may support one or more subcarrier spacing values. Correspondingly, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, etc. are currently considered. The symbol length Tu and subcarrier spacing Δf are directly related by the formula 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.

[0278] In the new radio system 5G-NR, for each numerology and each carrier, a resource grid of subcarriers and OFDM symbols is defined for each uplink and downlink. Each element of the resource grid is called a resource element and is specified based on a frequency index in the frequency domain and a symbol position in the time domain (see 3GPP TS 38.211 v15.6.0).

[0279] <Functional Separation Between NG-RAN and 5GC in 5G NR> Figure 16 shows the functional separation between NG-RAN and 5GC. The logical node of NG-RAN is gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0280] 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, dynamic allocation (scheduling) of resources to UEs in both uplink and downlink; - IP header compression, ciphering and integrity protection of data; - AMF selection at UE attach time if routing to the AMF cannot be determined from the information provided by the UE; - Routing of user plane data towards the UPF; - Routing of control plane information towards the AMF; - Connection setup and release; - Scheduling and transmission of paging messages; - Scheduling and transmission of system broadcast information (sourced from the AMF or Operation, Admission, Maintenance (OAM)); - Configuration of measurements and measurement reports for mobility and scheduling; - Transport level packet marking in the uplink; - Session management; Support for network slicing; - QoS flow management and mapping to data radio bearers; - Support for UEs in RRC_INACTIVE state; - NAS message delivery function; - Radio access network sharing; - Dual connectivity; - Close coordination between NR and E-UTRA.

[0281] The Access and Mobility Management Function (AMF) hosts the following main functions: - Termination of Non-Access Stratum (NAS) signaling; - Security of NAS signaling; - Security control of Access Stratum (AS); - Signaling between Core Network (CN) nodes for mobility between 3GPP access networks; - Reachability to idle mode UEs (including control and execution of paging retransmissions); - Registration area management; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization including checking of roaming rights; - Mobility management control (subscription and policy); - Support for network slicing; - Selection of Session Management Function (SMF).

[0282] Furthermore, the User Plane Function (UPF) hosts the following main functions: - anchor point for intra-RAT / inter-RAT mobility (if applicable); - external PDU (Protocol Data Unit) session point for interconnection with data networks; - packet routing and forwarding; - packet inspection and policy rule enforcement for the user plane part; - traffic usage reporting; - uplink classifier to support routing of traffic flows to the data network; - branching point to support multi-homed PDU sessions; - QoS processing for the user plane (e.g. packet filtering, gating, UL / DL rate enforcement); - uplink traffic validation (mapping of SDF to QoS flows); - downlink packet buffering and triggering of downlink data notifications.

[0283] Finally, the Session Management Function (SMF) hosts the following main functions: session management; allocation and management of IP addresses for UEs; selection and control of UPF; configuration of traffic steering in the User Plane Function (UPF) to route traffic to the appropriate destination; policy enforcement and QoS of the control part; downlink data notification.

[0284] <RRC connection setup and reconfiguration procedure> Figure 17 shows some of the interactions between the UE, gNB, and AMF (5GC entities) when the UE transitions from RRC_IDLE to RRC_CONNECTED in the NAS part (see TS 38.300 v15.6.0).

[0285] RRC is a higher layer signaling (protocol) used to configure the UE and gNB. With this transition, the AMF prepares UE context data (including, for example, PDU session context, security keys, UE radio capabilities, 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, and the UE responding with a SecurityModeComplete message to the gNB. The gNB then sends an RRCReconfiguration message to the UE, and upon receiving an RRCReconfigurationComplete from the UE, the gNB performs reconfiguration to set up Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB). For signaling-only connections, the steps related to RRCReconfiguration are omitted because SRB2 and DRB are not set up. Finally, the gNB notifies the AMF that the setup procedure is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0286] Accordingly, the present disclosure provides a 5th Generation Core (5GC) entity (e.g., AMF, SMF, etc.) that includes: a control circuit that, upon operation, establishes a Next Generation (NG) connection with a gNodeB; and a transmitter that, upon operation, transmits an initial context setup message to the gNodeB via the NG connection so that a signaling radio bearer between the gNodeB and a user equipment (UE) is set up. Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling, including a resource allocation configuration information element (IE), to the UE via the signaling radio bearer. The UE then transmits in uplink or receives in downlink based on the resource allocation configuration.

[0287] <IMT Usage Scenarios Beyond 2020> Figure 18 shows some use cases for 5G NR. The 3rd Generation Partnership Project 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 specifications for enhanced mobile broadband (eMBB) has been completed. Current and future work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to expanding support for eMBB. Figure 18 shows some examples of envisioned usage scenarios for IMT beyond 2020 (see, for example, ITU-R M.2083 Figure 2).

[0288] The URLLC use case has stringent performance requirements for throughput, latency, and availability. It is envisioned as one of the enabling technologies for future applications such as wireless control of industrial production or manufacturing processes, remote medical surgery, automated power transmission and distribution in smart grids, and road safety. URLLC's ultra-high reliability is supported by identifying technologies that meet the requirements set by TR 38.913. Key requirements for NR URLLC in Release 15 include a target user plane latency of 0.5 ms on the uplink (UL) and 0.5 ms on the downlink (DL). The overall URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a 32-byte packet size with a user plane latency of 1 ms.

[0289] From a physical layer perspective, reliability can be improved in many possible ways. Current room for reliability improvement includes defining a separate CQI table for URLLC, more compact DCI formats, PDCCH repetition, etc. However, this room can be expanded to achieve ultra-high reliability as NR (with respect to the key requirements of NR URLLC) becomes more stable and developed. Specific use cases for NR URLLC in Release 15 include Augmented Reality / Virtual Reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0290] Additionally, the technology enhancements targeted by NR URLLC aim to improve latency and reliability. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level repetition in the data channel, and preemption in the downlink. Preemption means that a transmission with already allocated resources is stopped and the already allocated resources are used for another transmission with a later requested lower latency / higher priority. Therefore, a previously allowed transmission is preempted by a later transmission. Preemption is applicable regardless of the specific service type. For example, a transmission of service type A (URLLC) may be preempted by a transmission of service type B (eMBB, etc.). Technology enhancements for reliability improvement include a dedicated CQI / MCS table for a target BLER of 1E-5.

[0291] The use case of mMTC (massive machine type communication) is characterized by a very large number of connected devices that typically transmit relatively small amounts of data that are not sensitive to delays. These devices are required to be low-cost and have very long battery life. From the NR perspective, utilizing very narrow bandwidth portions is one solution that saves power and extends battery life from the UE's perspective.

[0292] As mentioned above, the scope of reliability improvement in NR is expected to be broader. One of the key requirements for all cases, for example, URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can improve reliability from a radio perspective and a network perspective. Generally, there are two to three key areas that can help improve reliability. These areas include compact control channel information, repetition of data channels / control channels, and diversity in the frequency, time, and / or spatial domains. These areas are generally applicable to reliability improvement regardless of the specific communication scenario.

[0293] For NR URLLC, further use cases with more stringent requirements are envisaged, such as factory automation, transportation, and power distribution, with high reliability (up to 10-6 level reliability), high availability, packet size up to 256 bytes, time synchronization down to a few μs (depending on the use case, the value can be 1 μs or a few μs depending on the frequency range and low latency in the order of 0.5 ms to 1 ms (e.g., 0.5 ms latency on the targeted user plane)).

[0294] Furthermore, for NR URLLC, there may be several technical enhancements from the physical layer perspective. These technical enhancements include PDCCH (Physical Downlink Control Channel) enhancements for compact DCI, PDCCH repetition, and increased PDCCH monitoring. Also, UCI (Uplink Control Information) enhancements relate to enhanced Hybrid Automatic Repeat Request (HARQ) and CSI feedback enhancements. There may also be PUSCH enhancements related to minislot-level hopping and retransmission / repetition enhancements. The term "minislot" refers to a Transmission Time Interval (TTI) that contains fewer symbols than a slot (a slot comprises 14 symbols).

[0295] <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 (Guaranteed Bit Rate QoS flows (GBR)) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Thus, at the NAS level, a QoS flow is the finest granularity of QoS classification in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI) carried in an encapsulation header over the NG-U interface.

[0296] For each UE, 5GC establishes one or more PDU sessions. For each UE, the NG-RAN establishes at least one Data Radio Bearer (DRB) for each PDU session, e.g., as shown above with reference to Figure 17. Additional DRBs for the QoS flows of that PDU session can be configured later (when this is up to the NG-RAN). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and 5GC associate UL and DL packets with QoS flows, while AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0297] Figure 19 shows the non-roaming reference architecture for 5G NR (see TS 23.501 v16.1.0, section 4.23). An Application Function (AF) (e.g., an external application server hosting 5G services, as illustrated in Figure 18) interacts with the 3GPP core network to provide services. For example, it may access a Network Exposure Function (NEF) to support applications that affect traffic routing, or interact with a policy framework for policy control (e.g., QoS control) (see Policy Control Function (PCF)). Based on operator deployment, Application Functions considered trusted by the operator can interact directly with associated Network Functions. Application Functions not permitted by the operator to directly access Network Functions interact with associated Network Functions using an external exposure framework via the NEF.

[0298] Figure 19 further illustrates further 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-provided services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and run in a cloud computing environment.

[0299] Therefore, the present disclosure provides an application server (e.g., an AF in a 5G architecture) comprising: a transmitter that, in operation, sends a request including QoS requirements for at least one of a URLLC service, an eMMB service, and an mMTC service to at least one of 5GC functions (e.g., an NEF, an AMF, an SMF, a PCF, an UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE according to the QoS requirements; and a control circuit that, in operation, performs a service using the established PDU session.

[0300] The present disclosure can be realized by software, hardware, or software in conjunction with hardware. Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may also be called an IC, system LSI, super LSI, or ultra LSI.

[0301] The integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0302] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology may be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

[0303] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a radio transceiver and processing / control circuitry. The radio transceiver may include a receiver and a transmitter, or both functions. The radio transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0304] The communication devices are not limited to portable or mobile devices, but also include any kind of non-portable or fixed equipment, devices, and systems, such as smart home devices (such as home appliances, lighting equipment, smart meters or measuring devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0305] Communications include data communications via cellular systems, wireless LAN systems, communication satellite systems, and the like, as well as data communications via combinations of these.

[0306] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0307] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0308] A terminal according to one embodiment of the present disclosure includes a receiving circuit that receives, in a first cell, control information regarding a reference point for a reference time in controlling the transmission timing of an uplink signal to a second cell different from the first cell, and a control circuit that controls the transmission timing based on the control information.

[0309] In one embodiment of the present disclosure, the control information indicates whether the reference point is a synchronization point of an uplink signal in the first cell or the second cell.

[0310] In one embodiment of the present disclosure, the receiving circuit receives information indicating whether the reference time is based on the first cell or the second cell.

[0311] In one embodiment of the present disclosure, when the information regarding the control of the transmission timing is generated in the base station of the second cell, the control information indicates that the reference point is the point at which the uplink signal is synchronized in the second cell.

[0312] In one embodiment of the present disclosure, when the information regarding the control of the transmission timing is generated in a device other than the base station of the second cell, the control information indicates that the reference point is the point at which the uplink signal is synchronized in the first cell.

[0313] In one embodiment of the present disclosure, the reference time for the second cell is expressed in absolute time.

[0314] A base station according to one embodiment of the present disclosure includes, in a first cell, a control circuit that determines control information regarding a reference point for a reference time in controlling the transmission timing of an uplink signal to a second cell different from the first cell, and a transmission circuit that transmits the control information.

[0315] In a communication method according to one embodiment of the present disclosure, a terminal receives, in a first cell, control information regarding a reference point for a reference time in controlling the transmission timing of an uplink signal to a second cell different from the first cell, and controls the transmission timing based on the control information.

[0316] In a communication method according to one embodiment of the present disclosure, a base station determines, in a first cell, control information regarding a reference point for a reference time in controlling the transmission timing of an uplink signal to a second cell different from the first cell, and transmits the control information.

[0317] One aspect of the present disclosure is useful in wireless communication systems.

[0318] REFERENCE SIGNS LIST 100 Base station 101 Data generation unit 102 Control unit 103, 206 Data transmission processing unit 104, 207 Wireless transmission unit 105, 201 Antenna 106, 202 Wireless reception unit 107, 203 Data reception processing unit 200 Terminal 204 Location information acquisition unit 205 Timing adjustment unit 300 NTN control device

Claims

1. a receiving circuit for receiving, in a first cell, information on a system frame number and a subframe number based on an uplink synchronization reference point as control information related to a second cell different from the first cell; a control circuit for determining a reference time in the auxiliary information based on the control information; A terminal comprising:

2. The reference time in the auxiliary information is at least one of a reference time in information about a satellite position and a parameter of uplink transmission timing control. The terminal according to claim 1.

3. The control information is a system frame number and a subframe number based on the timing of the first cell and a synchronization reference point of the uplink. The terminal according to claim 1.

4. The control information, in the case of a handover, is a system frame number and a subframe number based on the timing of the second cell and the uplink synchronization reference point of the second cell. The terminal according to claim 1.

5. The control information is, in a first case, a system frame number and a subframe number based on the timing of the first cell and a synchronization reference point of the uplink of the first cell, and, in a second case, a system frame number and a subframe number based on the timing of the second cell and a synchronization reference point of the uplink of the second cell. The terminal according to claim 1.

6. Control information regarding the timing of the first cell and a system frame number and a subframe number based on the uplink synchronization reference point of the first cell is received in a System Information Block (SIB), and control information regarding the timing of the second cell and a system frame number and a subframe number based on the uplink synchronization reference point of the second cell is received in a message for RRC reconfiguration. The terminal according to claim 1.

7. In a first cell, information on a system frame number and a subframe number based on an uplink synchronization reference point is received as control information regarding a second cell different from the first cell; determining a reference time in the auxiliary information based on the control information; Communication methods.

8. The reference time in the auxiliary information is at least one of a reference time in information about a satellite position and a parameter of uplink transmission timing control. The communication method according to claim 7.

9. The method of claim 8, wherein the control information is a system frame number and a subframe number based on the timing of the first cell and a synchronization reference point of the uplink. The communication method according to claim 7.

10. The control information, in the case of a handover, is a system frame number and a subframe number based on the timing of the second cell and a synchronization reference point of the uplink of the second cell. The communication method according to claim 7.

11. The control information is, in a first case, a system frame number and a subframe number based on the timing of the first cell and a synchronization reference point of the uplink of the first cell, and, in a second case, a system frame number and a subframe number based on the timing of the second cell and a synchronization reference point of the uplink of the second cell. The communication method according to claim 7.

12. Control information regarding the timing of the first cell and a system frame number and a subframe number based on the uplink synchronization reference point of the first cell is received in a System Information Block (SIB), and control information regarding the timing of the second cell and a system frame number and a subframe number based on the uplink synchronization reference point of the second cell is received in a message for RRC reconfiguration. The communication method according to claim 7.

13. A control circuit for determining a reference time in the auxiliary information in the first cell; a transmitting circuit for transmitting, in a first cell, information on a system frame number and a subframe number based on an uplink synchronization reference point as control information regarding a second cell different from the first cell and including the reference time; A base station comprising:

14. The reference time in the auxiliary information is at least one of a reference time in information about a satellite position and a parameter of uplink transmission timing control. The base station according to claim 13.

15. The control information is a system frame number and a subframe number based on the timing of the first cell and a synchronization reference point of the uplink of the first cell. The base station according to claim 13.

16. The control information, in the case of a handover, is a system frame number and a subframe number based on the timing of the second cell and a synchronization reference point of the uplink of the second cell. The base station according to claim 13.

17. The control information is, in a first case, a system frame number and a subframe number based on the timing of the first cell and a synchronization reference point of the uplink of the first cell, and, in a second case, a system frame number and a subframe number based on the timing of the second cell and a synchronization reference point of the uplink of the second cell. The base station according to claim 13.

18. Control information regarding the timing of the first cell and a system frame number and a subframe number based on the uplink synchronization reference point of the first cell is received in a System Information Block (SIB), and control information regarding the timing of the second cell and a system frame number and a subframe number based on the uplink synchronization reference point of the second cell is received in a message for RRC reconfiguration. The base station according to claim 13.

19. In a first cell, a reference time in the auxiliary information is determined; In a first cell, transmitting information of a system frame number and a subframe number based on an uplink synchronization reference point as control information regarding a second cell different from the first cell, the control information including the reference time; Communication methods.

20. The reference time in the auxiliary information is at least one of a reference time in information about a satellite position and a parameter of uplink transmission timing control.

20. The communication method of claim 19.

21. The control information is a system frame number and a subframe number based on the timing of the first cell and a synchronization reference point of the uplink of the first cell.

20. The communication method of claim 19.

22. The control information, in the case of a handover, is a system frame number and a subframe number based on the timing of the second cell and a synchronization reference point of the uplink of the second cell.

20. The communication method of claim 19.

23. The control information is, in a first case, a system frame number and a subframe number based on the timing of the first cell and a synchronization reference point of the uplink of the first cell, and, in a second case, a system frame number and a subframe number based on the timing of the second cell and a synchronization reference point of the uplink of the second cell.

20. The communication method of claim 19.

24. Control information regarding the timing of the first cell and a system frame number and a subframe number based on the uplink synchronization reference point of the first cell is received in a System Information Block (SIB), and control information regarding the timing of the second cell and a system frame number and a subframe number based on the uplink synchronization reference point of the second cell is received in a message for RRC reconfiguration.

20. The communication method of claim 19.

25. A method for receiving, in a first cell, control information relating to a second cell different from the first cell; A process of determining a reference time in the auxiliary information based on the control information; and Integrated circuits.

26. A process for determining a reference time in the auxiliary information in a first cell; and transmitting, in a first cell, control information regarding a second cell different from the first cell, the control information including the reference time. Integrated circuits.