Terminal and communication method

Abstract

This terminal comprises: a control unit that, when transitioning to a radio resource control (RRC) idle state or an RRC inactive state in a non-terrestrial network (NTN), starts measurement on the basis of whether or not a first condition is satisfied, and determines a cell to be used in cell selection or cell reselection on the basis of whether or not a second condition is satisfied; and a communication unit that camps on the cell determined by the cell selection or the cell reselection and executes communication.

Description

Terminal and Communication Method

[0001] The present invention relates to a terminal and a communication method in a wireless communication system.

[0002] In NR (New Radio), which is a successor system to LTE (Long Term Evolution) (also referred to as "5G"), technologies that meet requirements such as a large-capacity system, high data transmission speed, low latency, simultaneous connection of a large number of terminals, low cost, and power saving are being studied (for example, Non-Patent Document 1).

[0003] Currently, NTN (Non-Terrestrial Network) is also being studied. NTN uses a non-terrestrial network such as a satellite to provide services to areas that cannot be covered mainly in terms of cost by a terrestrial 5G network (for example, Non-Patent Document 2 and Non-Patent Document 3).

[0004] 3GPP TS 38.300 V18.0.0 (2023-12)3GPP TR 38.821 V16.2.0 (2023-03)Kohashi et al., "A Study on Downlink Frequency Sharing in a HAPS Mobile Communication System", IEICE General Conference, B-17-1, 20203GPP TS 38.211 V18.1.0 (2023-12)3GPP TS 38.331 V18.0.0 (2023-12)3GPP TS 38.304 V18.0.0 (2023-12)3GPP TS 38.133 V18.4.0 (2023-12)

[0005] Since NTN mobility reuses, for example, the mobility mechanism in TN, it is not optimized for NTN. Therefore, there is a problem that the cell selection mechanism has low accuracy, is wasteful, and is unstable. By applying cell selection or cell reselection criteria considering NTN-specific information, it may be possible to appropriately determine the cells to be used.

[0006] The present invention has been made in view of the above points, and an object thereof is to enhance mobility in NTN (Non-Terrestrial Network).

[0007] According to the disclosed technology, a terminal is provided having a control unit that, when transitioning to an RRC (Radio Resource Control) idle state or an RRC inactive state in an NTN (Non-Terrestrial Network), starts measurement based on whether a first condition is met and determines a cell to be used in cell selection or cell re-selection based on whether a second condition is met, and a communication unit that camps on to the cell determined by the cell selection or cell re-selection and performs communication.

[0008] According to the disclosed technology, it is possible to enhance mobility in NTN (Non-Terrestrial Network).

[0009] This is a diagram showing an example of NTN (1). This is a diagram showing an example of NTN (2). This is a diagram showing an example of NTN (3). This is a diagram showing an example of NTN (4). This is a diagram showing an example of NTN (5). This is a flowchart for explaining an example of cell selection in an embodiment of the present invention. This is a diagram showing an example of the functional configuration of the base station 10 in an embodiment of the present invention. This is a diagram showing an example of the functional configuration of the terminal 20 in an embodiment of the present invention. This is a diagram showing an example of the hardware configuration of the base station 10 or terminal 20 in an embodiment of the present invention. This is a diagram showing an example of the configuration of the vehicle 2001 in an embodiment of the present invention.

[0010] Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which the present invention is applied are not limited to those described below.

[0011] In the operation of the wireless communication system according to the embodiments of the present invention, existing technologies may be used as appropriate. However, such existing technologies include, for example, existing LTE, but are not limited to existing LTE. Furthermore, the term "LTE" as used herein has a broad meaning that includes LTE-Advanced and LTE-Advanced and later technologies (e.g., NR), unless otherwise specified.

[0012] Furthermore, in the embodiments of the present invention described below, terms such as SS (Synchronization signal), PSS (Primary SS), SSS (Secondary SS), PBCH (Physical broadcast channel), PRACH (Physical random access channel), PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), PUCCH (Physical Uplink Control Channel), and PUSCH (Physical Uplink Shared Channel), which are used in existing LTE systems, will be used. This is for convenience of description, and similar signals, functions, etc., may be called by other names. Also, the above terms in NR correspond to NR-SS, NR-PSS, NR-SSS, NR-PBCH, NR-PRACH, NR-PDCCH, NR-PDSCH, NR-PUCCH, NR-PUSCH, etc. However, even if a signal is used in NR, it is not necessarily explicitly stated as "NR-".

[0013] Furthermore, in the embodiments of the present invention, the duplex system may be a TDD (Time Division Duplex) system, an FDD (Frequency Division Duplex) system, or any other system (for example, a Flexible Duplex).

[0014] Furthermore, in the embodiments of the present invention, "configuring" wireless parameters may mean that predetermined values ​​are pre-configured, or that wireless parameters notified from the base station 10 or terminal 20 are configured.

[0015] Figure 1 shows an example of NTN (1). NTN (Non-Terrestrial Network) uses non-terrestrial equipment such as satellites to provide services to areas that cannot be covered by terrestrial 5G networks, mainly due to cost constraints. Furthermore, NTN can provide more reliable services. For example, it is envisioned to be applied to IoT (Inter-of-Things), ships, buses, trains, and critical communications. NTN also has scalability through efficient multicast or broadcast.

[0016] As an example from NTN, as shown in Figure 1, satellite 10A can retransmit signals transmitted from ground base station 10B to provide service to areas where ground base stations are not located, such as mountainous regions.

[0017] The terrestrial 5G network may have the configuration described below. The terrestrial 5G network includes one or more base stations 10 and terminals 20. The base station 10 is a communication device that provides one or more cells and communicates wirelessly with the terminals 20. The physical resources of the radio signal are defined in the time domain and the frequency domain, the time domain may be defined by the number of OFDM symbols, and the frequency domain may be defined by the number of subcarriers or resource blocks. The base station 10 transmits synchronization signals and system information to the terminals 20. The synchronization signals are, for example, NR-PSS and NR-SSS. The system information is transmitted, for example, in NR-PBCH and is also called broadcast information.

[0018] Base station 10 transmits control signals or data to terminal 20 via DL (Downlink) and receives control signals or data from terminal 20 via UL (Uplink). Both base station 10 and terminal 20 are capable of transmitting and receiving signals using beamforming. Furthermore, both base station 10 and terminal 20 are capable of applying MIMO (Multiple Input Multiple Output) communication to DL or UL. In addition, both base station 10 and terminal 20 may communicate via SCell (Secondary Cell) and PCell (Primary Cell) using CA (Carrier Aggregation).

[0019] Terminal 20 is a communication device equipped with wireless communication capabilities, such as a smartphone, mobile phone, tablet, wearable device, or M2M (Machine-to-Machine) communication module. Terminal 20 receives control signals or data from base station 10 via DL and transmits control signals or data to base station 10 via UL, thereby utilizing various communication services provided by the wireless communication system.

[0020] Figure 2 shows an example of NTN (2). The area per cell or beam in NTN is much larger compared to terrestrial networks (TN). Figure 2 shows an example of NTN configured by satellite retransmission. The connection between satellite 10A and NTN gateway 10B is called a feeder link, and the connection between satellite 10A and UE20 is called a service link.

[0021] As shown in Figure 2, the difference in delay between the near-side UE20A and the far-side UE20B is, for example, 10.3 ms for GEO (Geosynchronous orbit) and 3.2 ms for LEO (Low Earth orbit). The beam size in NTN is, for example, 3500 km for GEO and 1000 km for LEO.

[0022] Figure 3 shows an example of an NTN (3). As shown in Figure 3, an NTN is realized by a satellite in space or an aircraft in the air. For example, a GEO satellite may be located at an altitude of 35,786 km and have a geostationary orbit. For example, a LEO satellite may be located at an altitude of 500-2000 km and orbit with a period of 88-127 minutes. For example, a HAPS (High Altitude Platform Station) may be located at an altitude of 8-50 km and perform a circular flight.

[0023] As shown in Figure 3, the GEO satellite, LEO satellite, and HAPS aircraft may be connected to the ground station gNB via a gateway. The service area may also increase in the order of HAPS, LEO, and GEO.

[0024] For example, NTN can extend the coverage of a 5G network to areas that are not yet serviced or are already serviced. Also, for example, NTN can improve the continuity, availability, and reliability of services in ships, buses, trains, or other critical communications. The fact that it is NTN may be notified by the transmission of a special parameter to the terminal 20, and this special parameter may be, for example, a parameter related to the determination of Timing Advance (TA) based on information relating to satellites or aircraft.

[0025] Figure 4 shows an example of NTN (4). Figure 4 shows an example of an NTN network architecture assumed in the case of a transparent payload. As shown in Figure 4, the CN (Core Network) 10D, gNB 10C, and gateway 10B are connected. Gateway 10B is connected to satellite 10A via a feeder link. Satellite 10A is connected to terminal 20A or VSAT (Very small aperture terminal) 20B via a service link. NR Uu is established between gNB 10C and terminal 20A or VSAT 20B.

[0026] Furthermore, NTN's network architecture may employ FDD or TDD. Also, the ground cells may be fixed or mobile. Additionally, terminal 20 may have the capability to support GNSS (Global Navigation Satellite System). For example, FR1 may be assumed to be a power class 3 handheld device. Also, at least FR2 may be assumed to be a VSAT device.

[0027] Furthermore, NTN's network architecture may also assume a regenerative payload. For example, the gNB function may be mounted on a satellite or aircraft. Alternatively, the gNB-DU may be mounted on a satellite or aircraft, and the gNB-CU may be deployed as a ground station.

[0028] Figure 5 shows an example (5) of NTN. As shown in Figure 5, the TA in NTN includes a common TA corresponding to the distance from the satellite / HAPS 10A to the reference point (RP) in the feeder link, and a UE-specific TA corresponding to the distance from the satellite / HAPS 10A to the UE 20 in the service link. The TA in the service link is a UE-specific TA and differs depending on the location of the UE 20. The feeder link includes a user-transparent delay corresponding to the distance from the reference point to the gNB / gateway 10B.

[0029] The reference point for UL synchronization may be determined by the network implementation. For example, the reference point may be any point on the satellite, gNB, GW, or feeder link. In the gNB or GW, the time domains of DL and UL may be aligned to facilitate implementation. In the satellite, UE operations related to the common TA may not be performed to reduce the UE load.

[0030] In NTN, TA may be calculated, for example, as TTA = (NTA + NTA, UE - specific + NTA, common + NTA, offset) × TC (see Non-Patent Document 4).

[0031] In the case of PRACH, the NTA is 0 and is notified by a TA command via MAC-CE (Medium Access Control - Control Element). The NTA may also be a closed-loop TA.

[0032] NTA,UE-specific is the TA specific to the UE. NTA,UE-specific may be a value estimated by the UE using its own equipment to compensate for service link delays in advance. NTA,UE-specific is calculated based on the UE's position and the celestial position of the serving satellite.

[0033] NTA,common is a common TA controlled by the network. Hereafter, NTA,common will also be referred to as the common TA. For example, if the reference point is a satellite, a value of 0 is supported. NTA,offset may be a fixed value used for TA calculation as defined in the specification.

[0034] Mobility in NTN is being considered. For example, cell reselection between NTNs is being considered. Position-based or time-based measurement initiation may be performed for both cells fixed relative to the Earth and cells in motion. Adjacent cell information may be transmitted via SIB19. Cell selection between NTNs is being considered. For example, a UE may skip TN measurements based on TN coverage information broadcast via SIB25. Also, with regard to handover, time-based and position-based conditions may be supported for triggering a Conditional Handover (CHO). RACH-less handover may be supported for NTN-NTN handovers. Hard or soft switching of satellites may be supported.

[0035] With regard to UE measurement and cell reselection criteria, the mechanism for TN mobility is reused in the case of NTN mobility and does not need to be extended in R17 / 18 NR NTN mobility.

[0036] The UE can identify target cells and perform SS-RSRP (Reference Signal Received Power) and SS-RSRQ (Reference Signal Received Quality) measurements of the identified cells. Cell selection criteria based on RSRP / RSRQ measurements may be applied.

[0037] For example, mobility in RRC_IDLE and RRC_INACTIVE may be performed as follows (see Non-Patent Document 1).

[0038] The same operation as in TN may be applied to mobility in RRC_IDLE for NTN, or the same operation as in TN may be applied to mobility in RRC_INACTIVE for NTN.

[0039] The network may broadcast multiple tracking area codes (TACs) for each PLMN within an NR NTN cell. Changes to the TAC in the system information are under network control and may not be precisely synchronized with real-time beam irradiation on the ground.

[0040] In the case of NTN-TN mobility, the network may broadcast cell information regarding NR TN and EUTRA TN coverage areas in SIB25. This is supported for Earth-fixed, quasi-earth-fixed, and Earth-mobile cells. The coverage information is a list of geographical TN areas and also indicates the relevant frequency information. UEs can skip TN measurements based on the broadcasted TN coverage information.

[0041] The UE can implicitly determine the network type (terrestrial or non-terrestrial) by the presence of cellBarredNTN in SIB1. The NTN ephemeris is provided in SIB19. An NTN cell includes the ephemeris of the serving cell's NTN payload and optionally the ephemeris of the adjacent cell's NTN payload.

[0042] For example, the measurement at NTN may be performed as follows (see Non-Patent Document 1).

[0043] The same operations as those in the measurement in TN may be applied to the measurement in NTN.

[0044] The network may perform the following settings: - For each carrier and for a given set of cells according to UE capabilities, set multiple SMTCs (SS / PBCH block Measurement Timing Configuration) in parallel - Set measurement gaps based on multiple SMTCs - Assistance information (e.g., ephemeris, common TA parameter, k ｍａｃ ) is provided in SIB19 for the UE to perform measurements on adjacent cells in RRC_IDLE / RRC_INACTIVE / RRC_CONNECTED

[0045] The NW-controlled adjustment of SMTCs can be based on UE assistance information reported in RRC_CONNECTED. UEs in the RRC_IDLE / RRC_INACTIVE state can adjust SMTCs based on their location and the assistance information in SIB19.

[0046] UE assistance information consists of the service link propagation delay difference between the serving cell and adjacent cells. For UEs in the idle / non-active mode state, whether to perform NTN adjacent cell measurements on cells shown in SIB3 / SIB4 but not included in SIB19 may be determined by the UE implementation. For UEs in the connected mode, whether to perform NTN adjacent cell measurements on cells included in the measurement settings but not included in SIB19 may be determined by the UE implementation.

[0047] The UE can perform time-based and location-based measurements on adjacent cells in RRC_IDLE / RRC_INACTIVE. - Timing and location information associated with the serving cell are provided in SIB19. - The timing information refers to the UTC time when the serving cell stops providing services to the current geographical area. - The location information refers to the following.

[0048] - In a quasi-earth-fixed cell scenario, this includes a distance threshold to the reference position of the serving cell and a distance threshold to the reference position.

[0049] - In the Earth-moving cell scenario, this includes a distance threshold to the reference position of the serving cell at epoch time, and a distance threshold to the reference position.

[0050] Time-based measurement initiation may be applicable in the case of feeder link switching for cell (re)selection. Measurement rules for cell reselection based on timing and position information may be defined.

[0051] For example, the measurement rules for cell reselection may be as follows (see Non-Patent Document 6).

[0052] To limit the required measurements, the following rules are used by the UE: 1> Serving cell is Srxlev>S ＩｎｔｒａＳｅａｒｃｈＰ and Squal > S ＩｎｔｒａＳｅａｒｃｈＱ If the following conditions are met: 2> distanceThrush and referenceLocation are broadcast in SIB19, and the UE supports initiating location-based measurements and acquires location information: 3> If the distance between the UE and the serving cell reference location referenceLocation is shorter than distanceThrush, the UE does not need to perform intra-frequency measurements.

[0053] 3> Otherwise, the UE shall perform intra-frequency measurements.

[0054] 2> Otherwise, the UE is not required to perform intra-frequency measurements. 1> Otherwise, the UE shall perform intra-frequency measurements. 1> The UE shall apply the following rules to the NR inter-frequency and inter-RAT frequency included in the system information and provided to the UE with priority.

[0055] - For NR frequency intervals or RAT intervals that have a higher reselection priority than the current NR frequency interval, the UE shall perform measurements of the higher priority NR frequency intervals or RAT intervals (see Non-Patent Document 7).

[0056] If the t-Service for a serving cell is present in SIB19 and the UE supports time-based measurement initiation, the UE shall perform intra-frequency, inter-frequency, or inter-RAT measurements before the t-Service, regardless of the distance between the UE and the reference position of the serving cell, or whether the serving cell satisfies Srxlev > SIntraSearchP and Squal > SIntraSearchQ, or Srxlev > SNonIntraSearchP and Squal > SNonIntraSearchQ. The exact time to initiate measurements before the t-Service depends on the UE implementation. The UE shall perform higher-priority inter-NR frequency or inter-RAT frequency measurements regardless of the remaining service time of the serving cell (i.e., remaining time until the t-Service) (see Non-Patent Document 7).

[0057] For a UE camped on an NTN cell, if the UE supports skipping TN measurements and the UE obtains its location information, and if the coverAreaInfoList and tn-AreaIdList are broadcast in the system information, the UE may not perform TN frequency measurements regardless of the frequency policy if the UE is not within the TN coverage of the frequencies provided via the tn-AreaIdList.

[0058] Cell reselection for NR UE for satellite access may be as follows (see Non-Patent Document 7):

[0059] The UE shall measure the SS-RSRP and SS-RSRQ levels of the serving cells and evaluate the cell selection criterion S for each serving cell at least once per M1*N1 DRX cycle.

[0060] - For one SMTC set in the UE, if the SMTC periodicity (TSMTC) > 20 ms and the DRX cycle ≤ 0.64 seconds and NSMTC = 1, then M1 = 2. - If the SMTC periodicity (TSMTC) > 20 ms and the DRX cycle ≤ 0.64 seconds and 1 < NSMTC ≤ 4, then M1 = 2.5. - Otherwise, M1 may be 1.

[0061] Here, NSMTC is the number of SMTCs set by the SAN (Satellite Access Node). The UE shall filter the SS-RSRP and SS-RSRQ measurements of the serving cell using at least two measurements. Within the set of measurements used for filtering, at least two measurements shall be spaced at least by DRX cycles / 2.

[0062] Cell selection and re-selection may be performed as follows:

[0063] The UE shall perform measurements for the purposes of cell selection and re-selection. When evaluating the Srxlev and Squal of non-serving cells for the purpose of re-selection evaluation, the UE shall use the parameters provided by the serving cell, and for the final check of the cell selection criteria, the UE shall use the parameters provided by the target cell for cell re-selection.

[0064] The Non-access stratum (NAS) can control the RAT on which cell selection should be performed, for example, by indicating the RAT associated with the selected PLMN, and by maintaining a list of prohibited registration areas and equivalent PLMNs. The UE shall select a suitable cell based on the measurement and cell selection criteria in the RRC_IDLE or RRC_INACTIVE state.

[0065] To facilitate the cell selection process, stored information for several RATs may be used by the UE, if available. When camping on to a cell, the UE shall periodically search for a better cell according to the cell reselection criteria. If a better cell is found, that cell is selected. A change in cell may mean a change in the RAT. Further details regarding performance requirements for cell reselection can be found in Non-Patent Literature 7.

[0066] The cell selection condition S may also be satisfied if the following conditions are met (see Non-Patent Document 6).

[0067] Srxrev > 0 and Squal > 0, where SrvLev = Qrxlevmeas - (Qrxlevmin + Qrxlevminoffset) - Pcompensation - Qoffsettemp and Squal = Qqualmeas - (Qqualmin + Qqualminoffset) - Qoffsettemp

[0068] Traditionally, NTN Mobility in RRC_IDLE or RRC_INACTIVE as defined in 5G has been inaccurate, wasteful, and potentially unstable.

[0069] For example, due to very small differences in RSRP between the cell center and the cell edge, the determination of candidate cells for cell re-selection presents challenges in terms of low robustness and accuracy.

[0070] For example, there is a problem in TN cells where unnecessary measurements of NTN cells (i.e., NTN measurements) are performed. In NTN cells, UEs do not perform measurements to reduce power consumption if there are no UEs within the coverage area broadcast by SIB25. On the other hand, in TN cells, NTN cells are constantly monitored, and measurements may be unnecessary.

[0071] For example, there is the issue of frequent HO triggers. In the current cell selection process, the best cell may not be chosen, and further HO triggers may be immediately met. Unnecessary overhead and / or many disconnections may occur.

[0072] It should be noted that this embodiment is applicable to both 5G NTN and 6G NTN.

[0073] Figure 6 is a flowchart illustrating an example of cell selection in an embodiment of the present invention. In step S101, the UE is in idle mode (RRC_IDLE) or inactive mode (RRC_INACTIVE). In step S102, the UE initiates measurement and / or applies cell selection criteria for NTN Mobility based on a mechanism other than location or time-based. The UE may apply the cell selection criteria to cell selection or cell re-selection to determine which cell to use, camp on to that cell, and perform communication.

[0074] For NTN mobility in RRC_IDLE / RRC_INACTIVE, the UE may perform the following actions A) and / or B).

[0075] Action A) Measurement initiation may be performed based on a mechanism other than a position / time-based mechanism.

[0076] Depending on whether certain conditions are met or not, the UE may or may not perform the measurement. The measurement may be an intra-frequency measurement or an inter-frequency measurement.

[0077] Measurement of TA information-based data may be initiated. TA information may be any of the following: • Cell: TA information of the serving cell or TA information of an adjacent cell. • Type: UE-specific TA, applicable common TA parameters, UE estimated propagation delay, UE estimated T_TA, and combinations thereof.

[0078] The conditions related to TA information may be any of the following: • When the difference between the adjacent cell TA and the UE estimated TA is greater than or less than the threshold. • When the UE estimated adjacent cell TA is greater than the threshold. This threshold may be set via SIB19.

[0079] Velocity-based measurement initiation may be performed.

[0080] The speed-related conditions may be any of the following: • The UE supports speed-based measurement initiation and has acquired its own speed. • The UE speed relative to the serving satellite is less than or greater than the UE speed relative to the adjacent satellite.

[0081] Operation B) For NTN Mobility, any of the following 1)-3) may be applied as cell selection conditions, or a combination thereof.

[0082] 1) The conditions may also be based on the TA information of adjacent cells. For example, adjacent cells with smaller TA information or a smaller TA difference compared to the UE estimated TA of the serving cell may be included as candidate cells for cell reselection. For example, adjacent cells with TA information or a smaller TA difference compared to the UE estimated TA of the serving cell than a threshold or a range of values ​​may be included as candidate cells for cell reselection.

[0083] 2) The condition may also be based on the distance from the UE or serving cell reference position to the adjacent cell reference position. For example, adjacent cells with a small distance may be included as candidate cells for cell re-selection. For example, adjacent cells that have a distance smaller than a threshold or whose distance is within a certain range may be included as candidate cells for cell re-selection.

[0084] 3) The conditions may also be based on the service time of adjacent cells. For example, the service time of adjacent cells may be provided by adjacent cell information broadcast by SIB19. For example, adjacent cells with long service times may be included as candidate cells for cell reselection. For example, adjacent cells with service times longer than a threshold or within a certain range may be included as candidate cells for cell reselection.

[0085] The above thresholds or ranges of values ​​may be broadcast via SIB19, which is an SIB for NTN. The above thresholds or ranges of values ​​may be applied individually or simultaneously as a combination. The above criteria (TA information, distance, service time) may be used to reduce the number of candidate cells. For example, when a UE determines candidate cells for cell reselection, the UE may exclude cells that do not meet the conditions related to the above criteria. For example, adjacent cells with larger TA information or TA differences compared to the UE estimated TA of the serving cell may be excluded from the candidate cells for cell reselection.

[0086] A UE within an NTN cell may decide whether to perform or skip a measurement of the NTN cell based on information provided by the network.

[0087] 1) The type of information may also be: • NTN cell area ID. For example, the NTN area ID can be defined to identify an NTN coverage area in a TN system. • NTN cell reference position, e.g., cell center. • NTN cell distance radius. • NTN cell movement speed. • Multiple or a list of NTN coverage area information.

[0088] 2) The information may also be notified via the following signaling: - It may be broadcast via the TN cell's SIB.

[0089] 3) The behavior of a UE upon receiving such information may be as follows: If there is no UE in the area corresponding to the broadcasted NTN cell or frequency, the UE may skip measuring the NTN cell or frequency.

[0090] The operation in which a UE within an NTN cell decides whether to perform or skip measurement of the NTN cell based on information provided by the network may be performed, for example, in RRC_IDLE or RRC_INACTIVE.

[0091] The UE may prioritize the selection of the candidate cells for re-selection as follows:

[0092] Option 1) The cells to be used may be determined based on the priority of cell types. For example, the cell type may be a TN cell or an NTN cell. For example, the preferred cell type may be notified from BS to UE. Each cell may be associated with either TN or NTN.

[0093] Option 2) The cell to be used may be determined based on the measurement result and the "offset". For example, the offset may be applied to the measurement result to determine the cell. In the case of an RSRP or RSRQ-based mechanism, the RSRP or RSRQ offset may be specified. In the case of the TA, distance, or service time-based mechanism described above, the TA, distance, or service time offset may be specified. This may be used as the cell selection criterion S in the RSRP or RSRQ-based mechanism described above, or as the cell selection criterion based on TA, distance, or service time.

[0094] For example, the offset Qoffset_ntn may be applied to the above-mentioned cell selection criterion S as follows:

[0095] Srxlev=Q_rxlevmeas-(Q_rxlevmin+Q_rxlevminoffset)-P_compensation-Q_offset_temp-Q_offset_ntn

[0096] Squal=Q_qualmeas-(Q_qualmin+Q_qualminoffset)-Q_offset_temp-Q_offset_ntn

[0097] A similar mechanism may be applied to cell selection criteria based on TA, distance, or service time. The offset may be notified per cell, per cell group, or per cell type, or it may be predefined.

[0098] Option 3) The cells used may be determined based on the priority index. Each cell may be associated with a priority index. For example, cells with a higher priority index (smaller or larger priority value) may be selected. An offset related to priority may be specified, and such offset may be notified per cell, per cell group, or per cell type.

[0099] Option 4) The cells to be used may be determined based on the following information:

[0100] - Distance from the serving cell reference position. For example, candidate cells with a smaller distance from the serving cell reference position may be selected. - TA difference compared with the serving cell TA information. For example, candidate cells with a smaller TA compared with the serving cell TA information may be selected. - Service time. For example, candidate cells with a longer service time may be selected.

[0101] Furthermore, the above operation may be applied to a UE in the RRC_IDLE or RRC_INACTIVE state, for example. Also, instead of determining a single cell, the above operation may be applied to determining candidate cells for cell re-selection.

[0102] In the embodiment described above, the terminal 20 can apply cell selection or cell re-selection criteria in the NTN, taking into account NTN-specific information, to appropriately determine which cell to use.

[0103] In other words, it can enhance mobility within the NTN (Non-Terrestrial Network).

[0104] (Device Configuration) Next, an example of the functional configuration of the base station 10 and terminal 20 that perform the processes and operations described above will be explained. The base station 10 and terminal 20 include the functions to carry out the above-described embodiment. However, the base station 10 and terminal 20 may each be equipped with only some of the functions in the embodiment.

[0105] <Base Station 10> Figure 7 is a diagram showing an example of the functional configuration of a base station 10 in an embodiment of the present invention. As shown in Figure 7, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in Figure 7 is merely an example. Any functional classification and functional unit names are acceptable as long as they can perform the operations according to the embodiment of the present invention.

[0106] The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 and transmitting the signal wirelessly. The transmitting unit 110 also transmits inter-network node messages to other network nodes. The receiving unit 120 includes the function of receiving various signals transmitted from the terminal 20 and obtaining information from the received signals, for example, higher layer information. The transmitting unit 110 also has the function of transmitting NR-PSS, NR-SSS, NR-PBCH, DL / UL control signals, etc. to the terminal 20. The receiving unit 120 also receives inter-network node messages from other network nodes.

[0107] The configuration unit 130 stores pre-configured configuration information and various configuration information to be transmitted to the terminal 20. The contents of the configuration information include, for example, information related to communication at NTN.

[0108] As described in the embodiment, the control unit 140 performs control related to communication in NTN. The control unit 140 also controls communication with terminal 20 based on the UE capability report regarding wireless parameters received from terminal 20. The signal transmission function of the control unit 140 may be included in the transmission unit 110, and the signal reception function of the control unit 140 may be included in the reception unit 120.

[0109] <Terminal 20> Figure 8 is a diagram showing an example of the functional configuration of terminal 20 in an embodiment of the present invention. As shown in Figure 8, terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Figure 8 is merely an example. Any functional classification and functional unit names are acceptable as long as they can perform the operations according to the embodiment of the present invention.

[0110] The transmitting unit 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiving unit 220 wirelessly receives various signals and acquires signals from higher layers from the received physical layer signals. The receiving unit 220 also has the function of receiving NR-PSS, NR-SSS, NR-PBCH, DL / UL / SL control signals, etc. transmitted from the base station 10. For example, the transmitting unit 210 transmits PSCCH (Physical Sidelink Control Channel), PSSCH (Physical Sidelink Shared Channel), PSDCH (Physical Sidelink Discovery Channel), PSBCH (Physical Sidelink Broadcast Channel), etc. to other terminals 20 as D2D communication, and the receiving unit 120 receives PSCCH, PSSCH, PSDCH or PSBCH, etc. from other terminals 20.

[0111] The setting unit 230 stores various setting information received from the base station 10 by the receiving unit 220. The setting unit 230 also stores pre-configured setting information. The content of the setting information includes, for example, information related to NTN communications.

[0112] The control unit 240 performs control related to communication in NTN, as described in the embodiment. The signal transmission function of the control unit 240 may be included in the transmission unit 210, and the signal reception function of the control unit 240 may be included in the reception unit 220.

[0113] (Hardware Configuration) The block diagrams (Figures 7 and 8) used in the description of the above embodiments show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may be realized by combining the one device or the multiple devices with software.

[0114] Functions include, but are not limited to, judgment, decision, determination, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In all cases, as mentioned above, the method of implementation is not particularly limited.

[0115] For example, the base station 10, terminal 20, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 9 is a diagram showing an example of the hardware configuration of the base station 10 and terminal 20 according to one embodiment of the present disclosure. The above-mentioned base station 10 and terminal 20 may be physically configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0116] In the following explanation, the term "device" can be read as "circuit," "device," "unit," etc. The hardware configuration of the base station 10 and terminal 20 may include one or more of the devices shown in the figure, or it may be configured without some of the devices.

[0117] Each function in the base station 10 and terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and storage device 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of data reading and writing in the storage device 1002 and auxiliary storage device 1003.

[0118] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control devices, arithmetic units, registers, etc. For example, the control unit 140, control unit 240, etc., described above may be implemented by the processor 1001.

[0119] Furthermore, the processor 1001 reads programs (program code), software modules, or data from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 140 of the base station 10 shown in Figure 7 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Also, for example, the control unit 240 of the terminal 20 shown in Figure 8 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Although the above-described processes have been explained as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may also be transmitted from the network via a telecommunications line.

[0120] The storage device 1002 is a computer-readable recording medium and may consist of at least one of the following: ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, cache, main memory, etc. The storage device 1002 can store executable programs (program code), software modules, etc., for implementing a communication method according to one embodiment of the present disclosure.

[0121] The auxiliary storage device 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital multipurpose disk, a Blu-ray® disk), a smart card, flash memory (e.g., a card, a stick, a key drive), a floppy® disk, a magnetic strip, etc. The above-mentioned storage medium may also be a database, server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003.

[0122] The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc. The communication device 1004 may be configured to include, for example, a high-frequency switch, duplexer, filter, frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the transmitting and receiving antenna, amplifier section, transmitting and receiving section, transmission path interface, etc., may be implemented by the communication device 1004. The transmitting and receiving section may be implemented in a physically or logically separated manner, with a transmitting section and a receiving section.

[0123] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0124] Furthermore, each device, such as the processor 1001 and the storage device 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0125] Furthermore, the base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array), and some or all of each functional block may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components.

[0126] Figure 10 shows an example of the configuration of vehicle 2001. As shown in Figure 10, vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in this disclosure may be applied to a communication device mounted on vehicle 2001, for example, to the communication module 2013.

[0127] The drive unit 2002 consists of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel, which is operated by the user.

[0128] The electronic control unit 2010 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2029 installed in the vehicle 2001 are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0129] Signals from various sensors 2021 to 2029 include current signals from current sensor 2021 for sensing motor current, front or rear wheel rotation speed signals acquired by rotation speed sensor 2022, front or rear wheel air pressure signals acquired by air pressure sensor 2023, vehicle speed signals acquired by vehicle speed sensor 2024, acceleration signals acquired by acceleration sensor 2025, accelerator pedal depression signals acquired by accelerator pedal sensor 2029, brake pedal depression signals acquired by brake pedal sensor 2026, shift lever operation signals acquired by shift lever sensor 2027, and detection signals acquired by object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0130] The Information Service Unit 2012 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including a car navigation system, audio system, speakers, television, and radio, and one or more ECUs that control these devices. The Information Service Unit 2012 uses information acquired from external devices via a communication module 2013, etc., to provide various multimedia information and multimedia services to the occupants of the vehicle 2001. The Information Service Unit 2012 may include input devices that accept input from the outside (e.g., keyboard, mouse, microphone, switch, button, sensor, touch panel, etc.) and output devices that perform output to the outside (e.g., display, speaker, LED lamp, touch panel, etc.).

[0131] The driver assistance system unit 2030 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System)), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driver assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driver assistance functions or autonomous driving functions.

[0132] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via its communication port. For example, the communication module 2013 sends and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, the microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021-29 provided in the vehicle 2001.

[0133] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with external devices. For example, it can send and receive various types of information with external devices via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station or a mobile station.

[0134] The communication module 2013 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include the information based on the above input.

[0135] The communication module 2013 receives various information (traffic information, signal information, inter-vehicle information, etc.) transmitted from an external device and displays it on the information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may also be called an output unit, which outputs information (for example, outputs information to devices such as displays and speakers based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from the external device in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021-2029, etc., provided in the vehicle 2001.

[0136] (Summary of Embodiments) As described above, according to embodiments of the present invention, a terminal is provided which, in an NTN (Non-Terrestrial Network), when transitioning to an RRC (Radio Resource Control) idle state or an RRC inactive state, starts measurement based on whether a first condition is met and determines a cell to be used in cell selection or cell re-selection based on whether a second condition is met, and camps on to the cell determined by the cell selection or cell re-selection and performs communication.

[0137] With the above configuration, terminal 20 can apply cell selection or cell re-selection criteria in the NTN (Non-Terrestrial Network) while taking into account NTN-specific information, and appropriately determine which cell to use. In other words, it can enhance mobility in the NTN.

[0138] The control unit may determine the first condition based on information related to timing advance and information related to the speed of its own device. With this configuration, the terminal 20 can apply cell selection or cell re-selection criteria in the NTN, taking into account NTN-specific information, and appropriately determine which cell to use.

[0139] The control unit may determine the second condition based on information related to timing advance, the distance between the device and the cell's reference point, or the cell's service time. With this configuration, the terminal 20 can apply cell selection or cell re-selection criteria in NTN, taking into account NTN-specific information, to appropriately determine which cell to use.

[0140] The control unit may, when located in a Terrestrial Network (TN) cell, decide whether or not to skip measuring an NTN cell based on certain conditions. With this configuration, the terminal 20 can appropriately determine which cell to use in the NTN by applying cell selection or cell re-selection criteria, taking into account NTN-specific information.

[0141] The control unit may prioritize determining which cell to use based on the cell type, measurement results and offset, or priority index. With this configuration, the terminal 20 can appropriately determine which cell to use by applying cell selection or cell re-selection criteria in NTN, taking into account NTN-specific information.

[0142] Furthermore, according to an embodiment of the present invention, a communication method is provided in which a terminal performs the following steps when transitioning to an RRC (Radio Resource Control) idle state or an RRC inactive state in an NTN (Non-Terrestrial Network): starting measurement based on whether a first condition is met, determining a cell to be used in cell selection or cell re-selection based on whether a second condition is met, and camping on to the cell determined by the cell selection or cell re-selection and performing communication.

[0143] With the above configuration, terminal 20 can apply cell selection or cell re-selection criteria in the NTN (Non-Terrestrial Network) while taking into account NTN-specific information, and appropriately determine which cell to use. In other words, it can enhance mobility in the NTN.

[0144] (Supplement to Embodiments) Embodiments of the present invention have been described above, but the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, substitutions, etc. Specific numerical examples have been used to facilitate understanding of the invention, but unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention, and matters described in two or more items may be combined as needed, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. The processing procedures described in the embodiments may be rearranged as long as they do not contradict each other. For the convenience of explaining the processing, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be realized in hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to an embodiment of the present invention and the software operated by the processor of the terminal 20 according to an embodiment of the present invention may be stored in any suitable storage medium such as random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or other appropriate storage medium.

[0145] Furthermore, notification of information is not limited to the embodiments described herein and may be carried out by other means. For example, notification of information may be carried out by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling), broadcast information (MIB (Master Information Block), SIB (System Information Block)), other signals, or combinations thereof. Also, RRC signaling may be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0146] Each aspect / embodiment described in this disclosure may be applied to at least one of the following systems: LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), NR (new Radio), W-CDMA®, GSM®, CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth®, and other appropriate systems, as well as next-generation systems extended based thereon. Furthermore, multiple systems may be applied in combination (for example, a combination of at least one of LTE and LTE-A with 5G).

[0147] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described herein may be reordered, provided they are consistent with each other. For example, the methods described herein present various step elements in an exemplary order and are not limited to that specific order.

[0148] In this specification, specific operations performed by the base station 10 may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station 10, it is clear that various operations performed for communication with the terminal 20 can be performed by the base station 10 and at least one of the other network nodes (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station 10, the other network node may be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0149] The information or signals described in this disclosure may be output from a higher layer (or lower layer) to a lower layer (or higher layer). They may also be input and output via multiple network nodes.

[0150] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be transmitted to other devices.

[0151] The determination in this disclosure may be made by a value represented by one bit (0 or 1), by a Boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value).

[0152] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0153] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0154] The information, signals, etc. described in this disclosure may be represented using any of the various different techniques. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0155] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0156] The terms “system” and “network” as used in this disclosure are interchangeable.

[0157] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0158] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, and therefore, the various names assigned to these various channels and information elements are not restrictive in any way.

[0159] In this disclosure, terms such as "Base Station (BS)", "wireless base station", "base station equipment", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission / reception point", "cell", "sector", "cell group", "carrier", and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0160] A base station can accommodate one or more (e.g., three) cells. If a base station accommodates multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which may also be provided with communication services by a base station subsystem (e.g., a Remote Radio Head (RRH)). The terms “cell” or “sector” refer to part or all of the coverage area of ​​at least one of the base station and / or base station subsystems that provide communication services in that coverage.

[0161] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform control or operation based on the information.

[0162] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0163] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or several other appropriate terms.

[0164] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body refers to a movable object, and its speed of movement is arbitrary. This also includes the case when the mobile body is stationary. The mobile body includes, but is not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and items mounted on them. The mobile body may also be a mobile body that moves autonomously based on operation commands. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). Furthermore, at least one of the base station and the mobile station may include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0165] Furthermore, the term "base station" in this disclosure may be interpreted as "user terminal." For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be called, for example, D2D (Device-to-Device), V2X (Vehicle-to-Everything), etc.). In this case, the terminals 20 may have the functions that the base station 10 has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc., may be interpreted as side channel.

[0166] Similarly, the term "user terminal" in this disclosure may be replaced with "base station." In this case, the base station may be configured to have the same functions as the user terminal described above.

[0167] As used in this disclosure, the terms “determining” and “determining” may encompass a wide variety of actions. “Determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” may also include receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having been "judged" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having been "judged" or "decided" after some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0168] The terms “connected,” “coupled,” or any variation thereof, mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0169] The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard.

[0170] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0171] Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the first and second elements do not imply that only two elements may be employed, or that the first element must precede the second element in any way.

[0172] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0173] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR.

[0174] A wireless frame may consist of one or more frames in the time domain. Each of these frames in the time domain may be called a subframe. A subframe may further consist of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0175] Numerical logic may be communication parameters applied to at least one of the transmission and reception of a signal or channel. Numerical logic may include, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processes performed by the transceiver in the frequency domain, and specific windowing processes performed by the transceiver in the time domain.

[0176] A slot may consist of one or more symbols in the time domain (such as OFDM (Orthogonal Frequency Division Multiplexing) symbols, SC-FDMA (Single Carrier Frequency Division Multiple Access) symbols, etc.). A slot may also be a time unit based on neurologic.

[0177] A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. Minislots may also be called subslots. Minislots may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called a PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called a PDSCH (or PUSCH) mapping type B.

[0178] Wireless frames, subframes, slots, minislots, and symbols all represent units of time when transmitting a signal. Different names may be used for each of these terms.

[0179] For example, one subframe may be called a Transmission Time Interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. In other words, at least one of a subframe and a TTI may be a subframe in existing LTE (1 ms), a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0180] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, the base station schedules each terminal 20 to allocate wireless resources (such as the frequency bandwidth and transmission power available to each terminal 20) in TTI units. However, the definition of TTI is not limited to this.

[0181] TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, code words, etc., or it may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the actual time interval (e.g., number of symbols) in which the transport block, code block, code word, etc. are mapped may be shorter than the TTI.

[0182] Furthermore, if one slot or one mini-slot is referred to as a TTI, then one or more TTIs (i.e., one or more slots or one or more mini-slots) may constitute the minimum time unit for scheduling. In addition, the number of slots (number of mini-slots) that constitute this minimum time unit for scheduling may be controlled.

[0183] A TTI with a time length of 1 ms may be called a normal TTI, a long TTI, a normal subframe, a long subframe, a slot, etc. A TTI shorter than a normal TTI may be called a shortened TTI, a short TTI, a partial or fractional TTI, a shortened subframe, a short subframe, a mini slot, a sub slot, a slot, etc.

[0184] Furthermore, long TTIs (e.g., normal TTIs, subframes, etc.) may be interpreted as TTIs with a time length exceeding 1 ms, and short TTIs (e.g., shortened TTIs, etc.) may be interpreted as TTIs with a TTI length less than that of a long TTI but 1 ms or more.

[0185] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and in the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers in an RB may be the same regardless of the neurology, for example, 12. The number of subcarriers in an RB may be determined based on the neurology.

[0186] Furthermore, the time domain of the RB may contain one or more symbols and may be the length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc., may each consist of one or more resource blocks.

[0187] One or more RBs may also be called a Physical RB (PRB), Sub-Carrier Group (SCG), Resource Element Group (REG), PRB pair, RB pair, etc.

[0188] Furthermore, a resource block may consist of one or more resource elements (REs). For example, one RE may be a radio resource area comprising one subcarrier and one symbol.

[0189] A Bandwidth Part (BWP), also known as a partial bandwidth, may represent a subset of consecutive common resource blocks (RBs) for a particular neurology in a given carrier. These common RBs may be identified by an index of the RBs relative to a common reference point of the carrier. The PRBs may be defined and numbered within a given BWP.

[0190] A BWP may include a BWP for UL (UL BWP) and a BWP for DL ​​(DL BWP). One or more BWPs may be set within a single carrier for a UE.

[0191] At least one of the configured BWPs may be active, and the UE does not need to assume that it will transmit or receive a predetermined signal / channel outside of the active BWP. In this disclosure, terms such as "cell" and "carrier" may be read as "BWP".

[0192] The structures described above, such as wireless frames, subframes, slots, minislots, and symbols, are merely illustrative. For example, the number of subframes included in a wireless frame, the number of slots per subframe or wireless frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, and the number of symbols, symbol length, and cyclic prefix (CP) length within a TTI can be varied in various ways.

[0193] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0194] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0195] Each aspect / embodiment described in this disclosure may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0196] Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Therefore, the descriptions in the present disclosure are illustrative and not intended to be restrictive in any way.

[0197] 10 Base station 110 Transmitting unit 120 Receiving unit 130 Setting unit 140 Control unit 20 Terminal 210 Transmitting unit 220 Receiving unit 230 Setting unit 240 Control unit 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Front wheel 2008 Rear wheel 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 Rotation speed sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driver assistance system unit 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port (I / O port)

Claims

1. A terminal having, in an NTN (Non-Terrestrial Network), a control unit that, when transitioning to an RRC (Radio Resource Control) idle state or RRC inactive state, starts measurement based on whether a first condition is met and determines the cell to be used in cell selection or cell re-selection based on whether a second condition is met, and a communication unit that camps on to the cell determined by the cell selection or cell re-selection and performs communication.

2. The terminal according to claim 1, wherein the control unit determines the first condition based on information relating to timing advance and information relating to the speed of the device.

3. The terminal according to claim 1, wherein the control unit determines the second condition based on information relating to timing advance, the distance between the device and the cell's reference point, or the cell's service time.

4. The terminal according to claim 1, wherein the control unit determines whether or not to skip measurement of an NTN cell based on conditions when it is located in a TN (Terrestrial Network) cell.

5. The terminal according to claim 1, wherein the control unit preferentially determines which cell to use based on the cell type, measurement result and offset, or priority index.

6. A communication method in which a terminal performs the following steps when transitioning to an RRC (Radio Resource Control) idle state or an RRC inactive state in an NTN (Non-Terrestrial Network): starting measurement based on whether a first condition is met, determining a cell to be used in cell selection or cell re-selection based on whether a second condition is met, and camping on to the cell determined by the cell selection or cell re-selection and performing communication.

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