Satellite device for providing NTN access and method performed by same

Abstract

The present invention relates to a satellite device for providing NTN access and a method performed by the same. In an embodiment, a satellite device for providing non-terrestrial network access is provided. The satellite device for providing non-terrestrial network access may include at least one processor and at least one transceiver. The at least one processor may be configured to transmit, through the at least one transceiver, a message including handover-related information to a terminal on a cell provided by the satellite. The handover-related information may include information related to a group to which the satellite belongs, information related to a target satellite of a target cell used for handover of the terminal, information related to a terminal group to which the terminal belongs, information related to a condition of conditional handover of the terminal, and a position of the target satellite. Information related to at least one of velocity and trajectory.

Description

Technical Field

[0001] The present invention generally relates to a non-terrestrial network (NTN) that provides wireless communication services through a satellite located in an earth orbit or an aerial vehicle flying at high altitude instead of a ground base station, and more specifically, to an apparatus and method for selecting a cell in a non-terrestrial network. Background Art

[0002] In order to improve the terrestrial network that provides wireless communication systems, non-terrestrial networks are introduced. Non-terrestrial networks can provide communication services in areas where it is difficult to build terrestrial networks or in disaster situations. In addition, due to the recent reduction in satellite launch costs, access network environments can be effectively provided. Summary of the invention

[0003] In an embodiment, a satellite device for providing access to a non-terrestrial network NTN is provided. The satellite device for providing access to a non-terrestrial network NTN may include at least one processor and at least one transceiver. The at least one processor may be configured to send a message including handover related information to a terminal on a cell provided by the satellite through the at least one transceiver. The handover related information may include information related to the group to which the satellite belongs, information related to a target satellite of a target cell for handover of the terminal, information related to a terminal group to which the terminal belongs, information related to a condition of conditional handover of the terminal, and information related to at least one of the position, velocity, and orbit of the target satellite.

[0004] In an embodiment, a method performed by a satellite for providing access to a non-terrestrial network (NTN) is provided. The method may include the following steps: sending a message including handover related information to a terminal on a cell provided by the satellite. The handover related information may include information related to the group to which the satellite belongs, information related to a target satellite of a target cell for handover of the terminal, information related to a terminal group to which the terminal belongs, information related to a condition of conditional handover of the terminal, and information related to at least one of the position, velocity, and orbit of the target satellite.

[0005] In an embodiment, a non-transitory recording medium is provided. The non-transitory recording medium may include a memory for storing instructions. When the instructions are executed by at least one processor, a satellite for providing non-terrestrial network NTN access performs the following operations: sending a message including handover related information to a terminal on a cell provided by the satellite, the handover related information including information related to a group to which the satellite belongs, information related to a target satellite of a target cell for handover of the terminal, information related to a terminal group to which the terminal belongs, information related to a condition of conditional handover of the terminal, and information related to at least one of a position, a speed, and an orbit of the target satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 A wireless communication system is shown.

[0007] Figure 2A and Figure 2B An example of a non-terrestrial network (NTN) is shown.

[0008] Figure 3A An example of a control plane (C-plane) is shown.

[0009] Figure 3B An example of a user plane (U-plane) is shown.

[0010] Figure 4 An example of a resource structure in the time domain and frequency domain in a wireless communication system is shown.

[0011] Figure 5 An example of a network structure for NTN is shown.

[0012] Fig. 6A An example of a control plane for a regenerative satellite is shown.

[0013] Figure 6B An example of a user plane of a regenerative satellite is shown.

[0014] Fig. 7A An example of group switching in satellite communications is shown.

[0015] Figure 7B An example of handover of a non-terrestrial base station is shown.

[0016] Fig. 8A An example of system information for NTN is shown.

[0017] Figure 8BAn example of a radio resource control (RRC) message for NTN is shown.

[0018] FIG. 9A to FIG. 9B An example of signaling over the F1 interface in the NTN is shown.

[0019] Fig.10 An example of signaling through the XN interface in the NTN is shown.

[0020] FIG. 11A to FIG. 11B An example of signaling over the NG interface in the NTN is shown.

[0021] Fig. 12A An example of a switching process using a regenerating satellite is shown.

[0022] Fig. 12B An example of selecting a cell using a regenerative satellite is shown.

[0023] Fig.13 Examples of components of a satellite are shown.

[0024] Fig.14 An example of components of a terminal is shown. DETAILED DESCRIPTION

[0025] The terms used in this disclosure are used only to illustrate specific embodiments and may not be intended to limit the scope of other embodiments. Unless the context clearly indicates a different meaning, a singular expression includes a plural expression. The terms used herein, including technical or scientific terms, may have the same meaning as that generally understood by a person of ordinary skill in the technical field recorded in this disclosure. Among the terms used in this disclosure, the terms defined in a general dictionary may be interpreted as having the same or similar meaning as that in the context of the associated technology, and unless clearly defined in this disclosure, should not be interpreted as an ideal or overly formal meaning. Depending on the circumstances, even the terms defined in this disclosure should not be interpreted as excluding the embodiments of the present disclosure.

[0026] In the various embodiments of the present disclosure described below, the hardware-based approach method is used as an example. However, since the various embodiments of the present disclosure include technologies that use both hardware and software, the various embodiments of the present disclosure do not exclude the software-based approach method.

[0027] The terms used in the following description to refer to signals (e.g., signal, information, message, signaling), terms to refer to resources (e.g., symbol, slot, subframe, radio frame, subcarrier, resource element (RE), resource block (RB), bandwidth part (BWP), occasion), terms used for operation states (e.g., step, operation, procedure), terms to refer to data (e.g., data packet, user flow, information, bit, symbol, codeword), terms to refer to channels, terms to refer to network entities, terms to refer to constituent elements of devices, etc. are exemplified for the convenience of explanation. Therefore, the present disclosure is not limited to the terms described later, but other terms with equivalent technical meanings may be used.

[0028] In the following description, physical channel and signal may be used interchangeably with data or control signal. For example, physical downlink shared channel (PDSCH) is a term referring to a physical channel for transmitting data, but PDSCH may also be used to refer to data. That is, in the present disclosure, the expression "sending a physical channel" may be interpreted as being equivalent to the expression "sending data or a signal through a physical channel".

[0029] In the following disclosure, high-layer signaling refers to a signal transmission method in which a base station transmits a signal to a terminal using a downlink data channel of a physical layer, or in which a terminal transmits a signal to a base station using an uplink data channel of a physical layer. High-layer signaling can be understood as radio resource control (RRC) signaling or MAC control element (hereinafter referred to as "CE").

[0030] Furthermore, in the present disclosure, in order to determine whether a specific condition is met, the expression greater than or less than can be used, but this is only to express an example, and it is not intended to exclude the above or below record. The condition recorded as "above" can be replaced by "greater than", the condition recorded as "below" can be replaced by "less than", and the condition recorded as "above and less than" can be replaced by "greater than and below". Moreover, below, "A" to "B" represents at least one of the elements from A (including A) to B (including B). Hereinafter, "C" and / or "D" means including at least one of "C" and "D", that is, including "C", "D", "C" and "D".

[0031] In the present disclosure, signal quality may be, for example, at least one of reference signal received power (RSRP), beam reference signal received power (BRSRP), reference signal received quality (RSRQ), received signal strength indicator (RSSI), signal to interference and noise ratio (SINR), carrier to interference and noise ratio (CINR), signal to noise ratio (SNR), error vector magnitude (EVM), bit error rate (BER) and block error rate (BLER). Of course, in addition to the above examples, other terms with equivalent technical meanings or other metrics representing channel quality may also be used. In the following, in the present disclosure, high signal quality means that the signal quality value related to the signal size is large or the signal quality value related to the error rate is small. Higher signal quality may mean that a smooth wireless communication environment is guaranteed. And, the best beam may refer to a beam having the highest signal quality among the beams.

[0032] The present disclosure uses terms used in some communication specifications (e.g., the 3rd Generation Partnership Project (3GPP) and the European Telecommunications Standards Institute (ETSI)) to describe various embodiments, but this is only an example for description. The various embodiments of the present disclosure can also be easily modified and applied in other communication systems.

[0033] Figure 1 A wireless communication system is shown.

[0034] Reference Figure 1 , Figure 1 A terminal 110 and a base station 120 are shown, which are a part of a node using a radio channel in a wireless communication system using New Radio (NR) as a wireless interface of a Radio Access Technology (RAT). Figure 1 Only one base station is shown, but the wireless communication system may also include other base stations that are the same or similar to base station 120 (e.g., NR gNB).

[0035] The terminal 110 is a device used by a user and communicates with the base station 120 through a wireless channel. The link from the base station 120 to the terminal 110 is called a downlink (DL), and the link from the terminal 110 to the base station 120 is called an uplink (UL). Figure 1 As shown, the terminal 110 and other terminals can communicate through wireless channels between each other. At this time, the link (device-to-device link, D2D) between the terminal 110 and the other terminal is called a sidelink, and the sidelink can be mixed with the PC5 interface. In some other embodiments, the terminal 110 can operate independently of the user. According to one embodiment, the terminal 110 is a device for performing machine type communication (machine type communication, MTC), which may not be carried by the user. And, according to one embodiment, the terminal 110 may be a narrowband Internet of Things (NB-IoT) device.

[0036] In this specification, when describing systems and methods, terminal 110 can be an electronic device for transmitting voice and / or data to base station 120, which can in turn communicate with a network of devices (e.g., a public switched telephone network (PSTN), the Internet, etc.).

[0037] Furthermore, in addition to being called a terminal, terminal 110 may also be called a “user equipment (UE)”, “vehicle”, “customer premises equipment (CPE)”, “mobile station”, “subscriber station”, “remote terminal”, “wireless terminal”, “electronic device” or “user device”, “access terminal”, “mobile terminal”, “remote station”, “user terminal”, “subscriber unit”, “mobile device” or other terms with equivalent technical meanings.

[0038] In addition, examples of the terminal 110 include a cellular phone, a smart phone, a personal digital assistant (PDA), a laptop computer, a netbook, an e-reader, and a wireless modem, etc. In the 3GPP standard, the terminal 110 is representatively referred to as a user equipment (UE). However, since the scope disclosed in this specification should not be limited to the 3GPP standard, the terms "UE" and "terminal" may be used interchangeably in this specification to refer to the more general term "wireless communication device". UE may also be more generally referred to as a terminal device.

[0039] The base station 120 is a network infrastructure that provides wireless access to the terminal 110. The base station 120 has a coverage range defined based on the distance at which a signal can be transmitted. In the 3GPP standard, in addition to "Node B", "evolved Node B (eNodeB, eNB)", "5G node (5th generationnode)", "next generation nodeB (next generationnodeB, gNB)", "home enhanced or evolved nodeB (HeNB)", the base station 120 is also generally referred to as "access point (access point, AP)", "wireless point (wireless point)", "transmission / reception point (transmission / reception point, TRP)" or other terms with equivalent technical meanings.

[0040] Since the scope of the contents disclosed in this specification should not be limited to the 3GPP standard, the terms "base station", "Node B", "eNB" and "HeNB" may be used interchangeably in this specification to refer to the more general term "base station". Also, the term "base station" may be used to refer to an access point. An access point may be an electronic device that provides wireless communication devices with access to a network (e.g., a local area network (LAN), the Internet, etc.). The term "communication device" may be used to refer to both a wireless communication device and / or a base station. An eNB or gNB may also be more generally referred to as a base station device.

[0041] The base station 120 may communicate with an NR core network (NR CN) entity 130. For example, the core network entity 130 may include an access and mobility management function (AMF) for a control plane such as access and mobility control functions of the terminal 110 and a user plane function (UPF) for a control function of user data.

[0042] The terminal 110 can perform beamforming with the base station 120. The terminal 110 and the base station 120 can send and receive wireless signals in a relatively low frequency band (for example, FR 1 (frequency range 1) of NR). In addition, the terminal 110 and the base station 120 can send and receive wireless signals in a relatively high frequency band (for example, FR 2 (or FR 2-1, FR 2-2, FR 2-3), FR 3) of NR, millimeter wave (mmWave) band (for example, 28GHz, 30GHz, 38GHz, 60GHz)). In order to improve the channel gain, the terminal 110 and the base station 120 can perform beamforming. Here, beamforming may include transmit beamforming and receive beamforming. The terminal 110 and the base station 120 can give directivity to the transmitted signal or the received signal. To this end, the terminal 110 and the base station 120 may select a serving beam through a beam search or beam management process. After selecting the serving beam, subsequent communications may be performed through resources having a quasi co-location (QCL) relationship with the resources transmitting the serving beam.

[0043] As long as the broad characteristics of the channel for transmitting symbols on the first antenna port can be inferred from the channel for transmitting symbols on the second antenna port, the first antenna port and the second antenna port can be evaluated as having a QCL relationship. For example, the broad characteristics may include at least one of delay spread, Doppler spread, Doppler shift, average gain, average delay, and spatial receiver parameter.

[0044] Both the terminal 110 and the base station 120 may perform beamforming, but the embodiments of the present disclosure are not limited thereto. In some embodiments, the terminal 110 may perform or not perform beamforming. Also, the base station 120 may perform or not perform beamforming. That is, only one of the terminal 110 and the base station 120 may perform beamforming, or both the terminal 110 and the base station 120 may not perform beamforming.

[0045] In the present disclosure, a beam refers to the spatial flow of a signal in a wireless channel, which is formed by one or more antennas (or antenna elements), and such a formation process may be referred to as beamforming. Beamforming may include at least one of analog beamforming or digital beamforming (e.g., precoding). Reference signals transmitted based on beamforming may include, for example, a demodulation reference signal (DM-RS), a channel state information reference signal (CSI-RS), a synchronization signal / physical broadcast channel (SS / PBCH), and a sounding reference signal (SRS). Furthermore, as a configuration of each reference signal, information elements (IE) such as CSI-RS resources or SRS-resources may be used, and such a configuration may include information associated with the beam. The information associated with the beam may indicate whether the corresponding configuration (e.g., CSI-RS resource) and other configurations (e.g., other CSI-RS resources in the same CSI-RS resource set) use the same spatial domain filter (spatial domain filter) or different spatial domain filters, or which reference signal is quasi-co-located (QCL), and if so, which type of QCL (e.g., QCL type A, B, C, D).

[0046] Hereinafter, to illustrate the embodiment, the terminal may be referred to as UE 110 and the base station may be referred to as gNB 120.

[0047] Figure 2A and Figure 2B An example of NTN is shown. Figure 2A An example of NTN using transparent satellites is shown. Figure 2B An example of NTN using regenerative satellites is shown. NTN represents a NG-RAN that provides non-terrestrial NR access for UEs (e.g., UE 110) through NTN payloads and NTN gateways carried on airborne or space-borne NTN vehicles. The NG-RAN may include more than one gNB (e.g., gNB 120).

[0048] Reference Figure 2A , NTN 200 represents a network environment according to the transparent satellite. In NTN 200, as gNB120, NTN payload 221 and NTN gateway 223 may be included. NTN payload 221 is a network node carried on a satellite or high altitude platform station (HAPS) that provides a connection function between a service link (described later) and a feeder link (described later). NTN gateway 223 is an earth station (earth station) set on the surface of the earth that uses the feeder link to provide a connection to NTN payload 221. NTN gateway 223 is a transport network layer (TNL) node. NTN 200 can provide non-terrestrial NR access to UE 110. NTN 200 can provide non-terrestrial NR access to UE 110 through NTN payload 221 and NTN gateway 223. The link between NTN payload 221 and UE 110 can be called a service link. The link between the NTN gateway 223 and the NTN payload 221 may be referred to as a feeder link. The feeder link may correspond to a wireless link.

[0049] The NTN payload 221 may receive radio protocol data from the UE 110 through a service link. The NTN payload 221 may transparently pass the radio protocol data to the NTN gateway 223 through a feeder link. Therefore, from the perspective of the UE 110, the NTN payload 221 and the NTN gateway 223 may be regarded as one gNB 120. The NTN payload 221 and the NTN gateway 223 may perform communication with the UE 110 through a Uu interface as a general radio protocol. That is, the NTN payload 221 and the NTN gateway 223 may perform radio protocol communication with the UE 110 like one gNB 120. The NTN gateway 223 may perform communication with the core network entity 235 (AMF or UPF) through an NG interface.

[0050] According to one embodiment, the NTN payload 221 and the NTN gateway 223 may utilize the following Figure 3A And, according to one embodiment, the NTN payload 221 and the NTN gateway 223 can utilize Figure 3B The wireless protocol stack in the user plane of the

[0051] exist Figure 2A1 and 2. The gNB 120 includes an NTN payload 221 and an NTN gateway 223, but the embodiments of the present disclosure are not limited thereto. For example, the gNB may include multiple NTN payloads. And, for example, the NTN payload may be provided by multiple gNBs. That is, Figure 2A The implementation scenario shown is an example and does not limit the embodiments of the present disclosure.

[0052] Reference Figure 2B , NTN 250 represents a network environment according to the regenerative satellite. NTN 250 may include a satellite 260 acting as a gNB120. Satellite 260 represents a space-borne vehicle carrying a regenerative payload communication transmitter set in low-earth orbit (LEO), medium-earth orbit (MEO) or geostationary earth orbit (GEO). Satellite 260 may be referred to as a regenerative payload or a regenerative satellite. Satellite 260 represents a payload configured to convert and amplify an uplink RF signal before sending it to a downlink, and the conversion of the signal may refer to digital processing that may include demodulation, decoding, recoding, remodulation and / or filtering. NTN 250 may include an entity connected to satellite 260 and deployed on the ground, namely NTN gateway 265. NTN gateway 265 is an earth station (earth station) deployed on the surface of the earth and providing a connection to satellite 260 using the feeder link. NTN 250 may provide non-terrestrial NR access to UE 110. NTN 250 may provide non-terrestrial NR access to UE 110 via satellite 260 and NTN gateway 265.

[0053] Satellite 260 may be configured to reproduce signals received from the earth. A Uu interface may be defined between satellite 260 and terminal 110. A satellite radio interface (SRI) on a feeder link may be defined between satellite 260 and NTN gateway 265. Figure 2B2 , the satellite 260 may provide an inter-satellite link (ISL) between satellites. The ISL is a transmission link between satellites, and the ISL may be a wireless interface (e.g., XN interface) or an optical interface defined by or not defined by 3GPP. The satellite 260 may communicate with the core network entity 235 (AMF or UPF) through an NG interface based on the NTN gateway 265. According to an embodiment, the satellite 260 may utilize the NG interface described later. Figure 3A And, according to one embodiment, the satellite 260 can utilize the wireless protocol stack in the control plane. Figure 3B The wireless protocol stack in the user plane.

[0054] although Figure 2B , the satellite 260 acting as the gNB 120 is described, but the embodiments of the present disclosure are not limited thereto. The gNB 120 according to the embodiment can be implemented as a distributed deployment (distributed deployment) using a centralized unit (CU) configured to perform the functions of the upper layers (upper layers) of the access network (e.g., packet data convergence protocol (PDCP), RRC) and a distributed unit (DU) configured to perform the functions of the lower layers. The interface between the CU and the DU can be referred to as an F1 interface. The CU is connected to more than one DU and can be responsible for functions of a higher layer than the DU. For example, the CU is responsible for the functions of the RRC and PDCP layers, and the DU and the radio unit (RU) can be responsible for the functions of the lower layers. The DU can be responsible for the functions of the radio link control (RLC), the media access control (MAC), and the physical (PHY) layers. In this distributed deployment, the satellite 260 can be used as a CU or DU constituting the gNB 120.

[0055] Figure 3A An example of a control plane (C-plane) is shown. In the following, at least some of the descriptions of gNB 120 may be understood as descriptions about satellite 260.

[0056] Reference Figure 3AIn the control plane, UE 110 and AMF 235 may perform non-access stratum (NAS) signaling. In the control plane, UE 110 and gNB 120 may perform communications corresponding to the specified protocol in the RRC layer, PDCP layer, RLC layer, MAC layer, and PHY layer, respectively.

[0057] In NTN access, the main functions of the RRC layer may include at least part of the following functions:

[0058] -Access Stratum (AS) and NAS related system information broadcast;

[0059] - Paging initiated by the 5G Core (5GC) or the Next Generation-Radio Access network (NG-RAN);

[0060] - Establishment, maintenance and release of the RRC connection between the UE and NG-RAN, including the following, more specifically, control of RLC, MAC and PHY:

[0061] -Addition, modification and release of carrier aggregation,

[0062] -Addition, modification and release of dual connectivity between NR or E-UTRA and NR;

[0063] -Including security functions of key management;

[0064] - Establishment, configuration, maintenance management and release of signaling radio bearers (SRB) and data radio bearers (DRB)

[0065] - Mobile features include:

[0066] - Handover and context transfer,

[0067] -UE cell selection and reselection and cell selection and reselection control,

[0068] - Inter-RAT mobility;

[0069] -Quality of service (QoS) management function;

[0070] -UE measurement reporting and control of reporting;

[0071] -Radio link failure sensing and recovery;

[0072] -Transfer of information from UE to NAS / transfer of information from NAS to UE.

[0073] In NTN access, the main functions of the PDCP layer may include at least part of the following functions:

[0074] -Header compression and decompression (ROHC only)

[0075] -Transfer of user data

[0076] -In-sequence delivery of upper layer PDUs

[0077] -Out-of-sequence delivery of upper layer PDUs

[0078] -PDCP PDU reordering for reception

[0079] -Duplicate detection of lower layer SDUs

[0080] -Retransmission of PDCP SDUs

[0081] -Ciphering and deciphering

[0082] -Timer-based SDU discard in uplink.

[0083] In NTN access, the main functions of the RLC layer may include at least part of the following functions:

[0084] -Transfer of upper layer PDUs

[0085] -In-sequence delivery of upper layer PDUs

[0086] -Out-of-sequence delivery of upper layer PDUs

[0087] -Error Correction through ARQ

[0088] -Concatenation, segmentation and reassembly of RLC SDUs

[0089] -Re-segmentation of RLC data PDUs

[0090] -Reordering of RLC data PDUs

[0091] -Duplicate detection

[0092] -Protocol error detection

[0093] -RLC SDU discard

[0094] -RLC re-establishment.

[0095] In NTN access, the MAC layer can be connected to multiple RLC layer devices configured in a terminal. The main functions of MAC may include at least part of the following functions:

[0096] -Mapping between logical channels and transport channels

[0097] -Multiplexing / demultiplexing of MAC SDUs

[0098] -Scheduling information reporting

[0099] -Error correction through HARQ

[0100] -Priority handling between logical channels of one UE

[0101] -Priority handling between UEs by means of dynamic scheduling

[0102] -MBMS service identification

[0103] -Transport format selection

[0104] -Padding.

[0105] In NTN access, the physical layer may perform channel coding and modulation on high-layer data, make it into OFDM symbols and transmit it through a wireless channel, or demodulate and channel decode the OFDM symbols received through a wireless channel and transmit them to a high-layer.

[0106] Figure 3B An example of a user plane is shown. In the following, at least some of the descriptions of gNB 120 may be understood as descriptions of satellite 260.

[0107] Reference Figure 3B In the user plane, UE 110 and gNB 120 may perform communications corresponding to the specified protocols in the SDAP layer, PDCP layer, RLC layer, MAC layer, and PHY layer, respectively. For the PDCP layer, RLC layer, MAC layer, and PHY layer other than the SDAP layer, reference may be made to Figure 3A Description.

[0108] In NTN access, the SDAP layer can provide 5GC QoS flows. A single protocol entity of SDAP can be configured for each PDU session. The functions of the SDAP layer may include at least part of the following functions:

[0109] -Mapping between QoS flows and data radio bearers;

[0110] - Indicates the QoS Flow Identifier (QFI) in both DL and UL packets.

[0111] Figure 4 An example of a resource structure in the time domain and the frequency domain supported by a wireless communication system to which the embodiments proposed in this specification can be applied is shown. Figure 4 The basic structure of the time domain-frequency domain is shown, which is a wireless resource area for transmitting data channels or control channels in the downlink or uplink in the 5G NR system to which this embodiment can be applied.

[0112] Reference Figure 4 , the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain is the OFDM symbol, which consists of N symb OFDM symbols 402 are aggregated to form a time slot 406. Figure 4 In the wireless communication system to which the present invention is applied, a radio frame 414 can be defined as consisting of 10 subframes of the same length of 1 ms, and thus has a length of 10 ms. In addition, a radio frame 414 can be divided into half-frames of 5 ms, and each half-frame includes 5 subframes. Figure 4 In the case of a 15 kHz subcarrier spacing, the time slot 406 consists of 14 OFDM symbols, but the length of the time slot can vary depending on the subcarrier spacing. For example, in the case of a 15 kHz subcarrier spacing, the time slot length is 1 ms and has the same length as the subframe. Differently, in the case of a 30 kHz subcarrier spacing, the time slot consists of 14 OFDM symbols, but a subframe can include two time slots of length 0.5 ms.

[0113] That is, a subframe and a frame are defined to have a fixed time length, and a time slot is defined by the number of symbols, so the time length may vary according to the subcarrier spacing. Figure 4 The radio resources supported by the wireless communication system to which the invention proposed in this specification can be applied are composed of symbols as multiple time resources and sub-carriers as multiple frequency resources, and each time resource and frequency resource can be represented as a two-dimensional resource grid. Figure 4 In the resource grid, a square of the smallest physical resource consisting of one subcarrier and one symbol is called a resource element (RE) 412.

[0114] In a wireless communication system to which the invention proposed in this specification can be applied, the minimum transmission unit in the frequency domain is a subcarrier, and the carrier bandwidth constituting the resource grid is N. BW The number of subcarriers is 404.

[0115] In the time-frequency domain, the basic unit of resources is a resource element (hereinafter referred to as "RE") 412, which can be represented by an OFDM symbol index and a subcarrier index. A resource block 408 may include multiple resource elements 412. In a wireless communication system to which the invention proposed in this specification can be applied, a resource block 408 (or a physical resource block (hereinafter referred to as "PRB")) may be defined as N in the time domain. symb consecutive OFDM symbols and N in the frequency domain SC RB In the NR system, resource block 408 can be defined as N consecutive subcarriers in the frequency domain. SC RB subcarriers 410. A resource block 408 includes N subcarriers 410 on the frequency axis. SC RB resource elements 412.

[0116] Generally speaking, the minimum data transmission unit is RB, and the number of subcarriers N SC RB The frequency domain may include common resource blocks (CRBs). Physical resource blocks (PRBs) may be defined in a portion of the bandwidth on the frequency domain. CRBs and PRB numbers may be determined based on subcarrier spacing. The data rate may be increased in proportion to the number of RBs scheduled to the terminal.

[0117] In the NR system, in the case of a frequency division duplex (FDD) system in which the downlink and uplink are divided and operated by frequency, the downlink transmission bandwidth and the uplink transmission bandwidth may be different from each other. The channel bandwidth represents the radio frequency (RF) bandwidth corresponding to the system transmission bandwidth. Table 1 shows a part of the correspondence between the system transmission bandwidth, subcarrier spacing, and channel bandwidth defined in the NR system in a frequency band (e.g., FR 1 (410 MHz to 7125 MHz)) lower than the upper limit defined in the standard (e.g., 7.125 GHz). In addition, Table 2 shows a part of the correspondence between the transmission bandwidth, subcarrier spacing, and channel bandwidth defined in the NR system in a frequency band (e.g., FR2 (24250 MHz to 52600 MHz) or FR2-2 (52600 MHz to 71000 MHz)) higher than the lower limit defined in the standard (e.g., 24.25 GHz). For example, in an NR system with a 100 MHz channel bandwidth with a 30 kHz subcarrier spacing, the transmission bandwidth consists of 273 RBs. In Tables 1 and 2, N / A may be a bandwidth-subcarrier combination that is not supported in the NR system.

[0118] [Table 1]

[0119]

[0120] [Table 2]

[0121]

[0122] Figure 5 An example of a network structure for NTN is shown. Satellite 260 may be carried on a space vehicle or aerial vehicle to provide structure, power, command, telemetry, attitude control of the satellite (corresponding HAPS), and appropriate thermal environment and radiation shielding. Figure 5 , satellite 260 is described as a regenerative payload as an example of the actions of a full base station (e.g., gNB 120).

[0123] Reference Figure 5 , the satellite 260 can act as a gNB 120. The gNB 120 can communicate with the terminal 110 or with the core network entity 130. Figure 5500 is shown as the core network entity 130. An NR Uu interface 502 may be utilized between the satellite 260 and the terminal 110. According to an embodiment, at least one radio bearer 520 may be generated between the satellite 260 and the terminal 110. For example, the radio bearer 520 may include a data radio bearer (DRB). For example, the radio bearer 520 may include a signaling radio bearer (SRB). An NG interface 504 may be utilized between the satellite 260 and the core network entity (e.g., AMF, UPF). For example, an N3 interface may be utilized between the satellite 260 and the UPF. For example, an N2 interface may be utilized between the satellite 260 and the AMF. According to an embodiment, a traffic tunnel may be generated between the satellite 260 and the core network entity 130. For example, a next generation user plane (NG-U) tunnel 530 may be generated between the satellite 260 and the UPF 550.

[0124] A packet data unit (PDU) session 540 may be generated between the UE 110 and the core network entity 130 (e.g., UPF 550). The PDU session 540 may be used to provide an end-to-end user plane connection between the terminal 110 and the data network through the UPF 550. The PDU session 540 may support more than one quality of service (QoS) flow. For example, the PDU session 540 may support a first QoS flow 511 and a second QoS flow 512. In the user plane, the radio bearer 520 may be mapped to the QoS flow (e.g., the first QoS flow 511, the second QoS flow 512). According to an embodiment, the satellite 260 is a gNB 120 and may perform mapping between DRBs and QoS flows.

[0125] although Figure 5 Although not shown, operations and maintenance (O&M) may be used to provide a wireless access network via satellite 260. O&M may provide one or more parameters associated with NTN 500 to gNB 120 (e.g., satellite 260). For example, O&M 510 may provide the following NTN-related parameters to gNB 120 at a minimum for operation:

[0126] a) Earth fixed beams: For each beam provided by a given NTN payload:

[0127] - the cell identifiers (NG and Uu) mapped to the beams,

[0128] - The reference location of the cell (e.g. the center and the area of ​​the cell);

[0129] b) Quasi Earth Fixed Beams: For each beam provided by a given NTN payload:

[0130] - the cell identifier (NG and Uu) and time window mapped to the beam,

[0131] - the reference location of the cell / beam (e.g. the center and range of the cell),

[0132] - time window for successive switch-overs (feeder links, service links),

[0133] - Identifiers and time windows of all satellites and NTN gateways providing services;

[0134] c) Earth moving beams: For each beam provided by a given NTN payload:

[0135] - Uu cell identifiers mapped to beams and mapping information related to fixed geographical areas reported to the NG, information related to the movement of the footprint of the beam in the earth,

[0136] - elevation relative to the NTN payload,

[0137] -Continuous service scheduling of NTN-gateway / gNB,

[0138] - Continuous switch-over scheduling (feeder link, service link).

[0139] Fig. 6A An example of a control plane for a regenerative satellite (eg, satellite 260 ) is shown.

[0140] Reference Fig. 6A UE 610 can support protocols of PHY layer, MAC layer, RLC layer, PDCP layer and RRC layer. Satellite 620 as gNB can support protocols of PHY layer, MAC layer, RLC layer, PDCP layer and RRC layer. For satellite 620, refer to the description of satellite 260. For the description of each layer protocol, refer to Figure 3A The interface between the UE 610 and the satellite 620 may be a Uu interface.

[0141] Satellite 620 is a gNB or part of a gNB mounted on a board, and can perform NG-RAN protocol functions. Satellite 620 can communicate (e.g., IP communication) with NTN gateway 630 located on the ground through SRI. Satellite 620 can access 5GC through NTN gateway 630. As a network entity for the 5GC, AMF 640 (e.g., AMF 235 and SMF650) is illustrated. Satellite 620 can support NG-AP layer, stream control transmission protocol (SCTP) layer, and IP layer protocols to communicate with 5GC. The NG-AP layer can be used between AMF640 as a 5GC entity and satellite 620 through NTN gateway on SCTP. NAS signaling between UE 610 and AMF 640 can be performed through satellite 620 and NTN gateway 630. The NAS signaling may include a NAS-mobility management (MM) interface for AMF 640. The NAS signaling may include NAS-SM relay and / or NAS-session management (SM) for SMF 650. The NAS signaling may be transmitted between AMF 640 as a 5GC entity and satellite 620 through NTN gateway 630 through NG-AP layer protocol.

[0142] exist Fig. 6A In the example of the satellite acting as a complete gNB, the embodiments of the present disclosure are described, but the embodiments of the present disclosure are not limited thereto. As a non-limiting example, the satellite may act as a gNB-DU with functional separation. Thus, the satellite may also be configured to support protocols of the RLC layer, the MAC layer, and the PHY layer.

[0143] Figure 6B An example of a user plane of a regenerative satellite (eg, satellite 260) is shown.

[0144] Reference Figure 6B UE 610 can support protocols of PHY layer, MAC layer, RLC layer, PDCP layer and SDAP layer. Satellite 620 as gNB can support protocols of PHY layer, MAC layer, RLC layer, PDCP layer and SDAP layer. The description of each layer protocol can refer to Figure 3B The interface between the UE 610 and the satellite 620 may be a Uu interface.

[0145] The satellite 620, as a gNB mounted on board, can perform NG-RAN protocol functions. The satellite 620 can communicate with the NTN gateway 630 located on the ground through SRI (e.g., IP communication). The satellite 620 can access the 5GC through the NTN gateway 630. As a network entity for the 5GC, the UPF 680 is illustrated. The satellite 620 can support the protocols of the general packet radio service tunneling protocol-user plane (GPRS (General Packet Radio Service) tunneling protocol-user plane, GTP-U) layer, the user datagram protocol (user datagram protocol, UDP) layer, and the IP layer to communicate with the 5GC. A PDU session (e.g., Figure 5 The SRI protocol stack can be used to transmit the UE user plane between the satellite and the NTN-gateway. The signal on the PDU session can be transmitted between the UPF 680 as 5GC and the satellite 620 through the NTN gateway 630 through the GTP-U tunnel.

[0146] exist Figure 6B In the example in which the satellite acts as a complete gNB, the embodiments of the present disclosure are not limited thereto. As a non-limiting example, the satellite may act as a gNB-DU with functional separation. Thus, the satellite may also be configured to support protocols of the RLC layer, the MAC layer, and the PHY layer.

[0147] Fig. 7A An example of group switching in satellite communications is shown.

[0148] Reference Fig. 7A , satellites moving on the same orbit 707 can provide services for the terminal. For example, the satellites may include a first satellite 721 and a second satellite 723. For the first satellite 721 and the second satellite 723, reference may be made to the description of the satellite 620. The satellites may be moved along the orbit 707 from Fig. 7A The terminals (e.g., UE 610-1, UE 610-2, ..., UE 610-n) may be served by a cell provided by the first satellite 721. When the first satellite 721 repeatedly moves on a designated orbit, the terminals (e.g., UE 610-1, UE 610-2, ..., UE 610-n) served by the first satellite 721 must inevitably switch to a new cell.

[0149] For example, assume that multiple terminals receiving services from a terrestrial fixed cell need to move to a new cell during a cell stop time or that a satellite moves to a location where a gateway needs to be switched. In the above case, all terminals need to be connected to the new cell. When the satellite providing a serving cell to the terminal switches from the first satellite 721 to the second satellite 723, the cell (e.g., PCell) may change even if the terminal does not move. In the above case, providing a separate handover command to each UE results in a large signaling overhead, and is therefore inefficient in terms of resource utilization. Moreover, in terms of system throughput, a large signaling overhead may result in a handover command being provided too quickly, or may result in a radio link failure (RLF). Therefore, the messages and information according to the embodiments of the present disclosure may be used to reduce the signaling overhead between the terminal and the source cell (e.g., the cell of the first satellite 721) in the handover command. According to one embodiment, in order to reduce the signaling overhead, a time-based conditional handover (CHO) may be configured. The network knows the time range in which the terminal needs to switch, and may cause the terminal to initiate a handover through specific trigger conditions (e.g., time range and RSRP-based events). In addition, the messages and information according to the embodiments of the present disclosure may be used to reduce congestion in the target cell. According to one embodiment, in order to reduce congestion in the target cell, a RACH-less handover may be utilized. According to one embodiment, a random access preamble transmission to the target cell may be initiated by introducing a random backoff mechanism.

[0150] Figure 7B An example of handover of a non-terrestrial base station (eg, satellite 620) is shown.

[0151] Reference Figure 7B , the switching situation in the satellite 620 can be performed not only between satellites (for example, switching between the first satellite 721 and the second satellite 723), but also between satellites and ground base stations (for example, base station 720). For switching between satellites, the interface between satellites can be called an inter-satellite link. For example, when each satellite acts as a gNB, the interface between the satellites can be referred to as an XN interface. Since the satellite has a geographical characteristic of orbiting a specified orbit, the network can provide more efficient mobility management (for example, cell selection, switching) to the terminal (for example, UE 610) based on the orbit of the satellite. Not only in switching between satellites, but also in switching between satellites and ground base stations, when the satellite moves along the orbit and moves away from a specific area, the ground base station replaces the satellite to provide communication services to the area previously served by the satellite.

[0152] Fig. 8A An example of system information for NTN is shown.

[0153] Reference Fig. 8A In action 801, the satellite 620 may broadcast system information. The system information may include information related to the satellite. The UE 610 may receive the system information. The UE 610 may receive the system information from the satellite 620. According to an embodiment, the system information is a system information block (SIB) 801, which may be a previously defined SIB (e.g., SIB19, SIB1, SIB2) or a SIB defined separately for a regenerated satellite (e.g., SIB extension (SIB extend, SIBx)). For example, SIBx may include information as shown in the following table.

[0154] [Table 3]

[0155]

[0156] "ntn-Config" indicates parameters for accessing a wireless network through NTN access, and the following table (e.g., Table 4) may be referred to. "t-service" may indicate time information related to a point in time at which a cell provided by the NTN quasi-Earth fixed system stops providing service to the area for which it is currently responsible. "referenceLocation" indicates a reference location of a service cell provided by the NTN quasi-Earth fixed system. "distanceThresh" indicates the distance from the reference location of the service cell, and may be used for location-based measurements in the RRC IDLE or RRC INACTIVE states. "ntn-NeighCellConfigList" may indicate information about neighboring cells of a cell provided by a satellite (e.g., satellite 620).

[0157] [Table 4]

[0158]

[0159] "epochTime" indicates the epoch time of NTN support information. When specifically provided through SIB or provided through dedicated signaling, the epoch time indicates the start time of the DL subframe and may display the number of the subframe signaled together with the system frame number (SFN) and the support information. As a non-limiting example, for higher granularity, "epochTime" may include an information element indicating a symbol in addition to a subframe. The IE may indicate one of 0 to 13 and indicate one of 14 symbols.

[0160] "ntn-UlSyncValidityDuration" is the validity duration of the auxiliary information (e.g., ephemeris information, common TA parameters) set by the network. In other words, the validity duration indicates the maximum time that the support information can be applied without obtaining new NTN support information. The above time period can start from the epoch time. "cellSpecificKoffset" indicates the scheduling offset used for the timing relationships modified for NTN. "kmac" indicates the scheduling offset used when the downlink timing and uplink timing are inconsistent. "ta-Info" may include information for TA (timing advance). The information for TA may include "ta-Common" (common TA controlled by the network), "ta-CommonDrift" indicating the drift rate of the common TA, and "ta-CommonDriftVariant" indicating the variation of the drift rate. "ntn-PolarizationDL" and "ntn-PolarizationUL" represent the polarization information in DL and UL, respectively. "ephemerisInfo" indicates ephemeris information, and may be exemplified as the following table (eg, Table 5). "ta-Report" indicates that TA reporting is activated during RRC connection establishment, RRC connection resume, and RRC connection reestablishment.

[0161] [Table 5]

[0162]

[0163] "positionX", "positionY", and "positionZ" represent the position state vector of the earth-centered, earth-fixed (ECEF) coordinate system in the xyz coordinate system. The unit is meter, and one step represents 1.3 meters. For example, the actual value may be the field value * 1.3. "velocityX", "velocityY", and "velocityZ" represent the velocity state vector of ECEF in the xyz coordinate system. One step represents 0.06 m / s (meters per second). For example, the actual value may be the field value * 0.06. "semiMajorAxis" is the semi-major axis, "eccentricity" is the eccentricity, "periapsis" is the periapsis, "longitude" is the longitude, "inclination" is the inclination, and "meanAnomaly" is the mean anomaly, which represents the ratio of the elliptical orbit period passed by the orbiting object after passing the periapsis.

[0164] In addition to the IEs defined in Tables 3 to 5 above, the parameters delivered through the system information may include various satellite-related information.

[0165] 1. Satellite constellation and identification information

[0166] The satellite 620 may send identification information about a group (hereinafter, satellite group) including the satellite 620 to the UE 610. According to an embodiment, satellites orbiting the same orbit may be classified into the same satellite group. For example, satellites in the same satellite group may share the same orbit. As an example, satellites in the same satellite group may have the same orbit information (e.g., "Orbital-r19" IE) in the ephemeris information. As a non-limiting example, the system information may include orbit information specific to the satellite group, rather than including orbit information for each satellite. According to another embodiment, satellites using the same NTN gateway (e.g., NTN gateway 630) may be classified into the same group. The NTN gateway may be used at a fixed position on the ground. Therefore, satellites connected to the NTN gateway may be understood to be deployed within a certain distance from the NTN gateway. Therefore, satellites gathered in a specific area may be connected to the NTN gateway together. Since the satellite acts as an independent base station, more than one cell may be provided. Therefore, in addition to the physical cell ID, the satellite may also need to specify a unique ID. For example, in order to identify the satellite, the gNB ID may be utilized. As another example, in order to identify the satellite, the gNB-DU ID may be utilized. As yet another example, in order to identify the satellite, a separately defined ID may be used. The satellite group may be identified by a satellite group ID. For example, a satellite may be identified by the satellite group ID and an intra-group satellite ID. As another example, a satellite may be given a separate satellite ID independent of a group. The satellite 620 may broadcast information about the satellite 620 or information about satellites included in the same group as the satellite 620 as system information. The UE 610 may identify information about surrounding satellites through identification information of the satellite 620 or identification information of a satellite group to which the satellite 620 belongs.

[0167] 2. Class Information

[0168] Referring to Table 5, when indicating the position of the ephemeris information, approximately 26 bits of information are required for each axis (e.g., x-axis, y-axis, z-axis). As the number of satellites increases, there may be many other satellites in orbit around the Earth in addition to the satellites currently providing service cells. Therefore, when indicating the position of each satellite, approximately 84 bits (26 bits per satellite) are required for the xyz coordinate system in three-dimensional space, which may impose a burden on satellites configured to act according to communication protocols. Therefore, in order to reduce the burden on satellite operation and signal processing, classes can be used instead of specific values. For example, the range of the position state vector "PositionStateVector-r19" is "(-33554432..33554431)", but it can be divided into four categories, as shown in Table 6 below.

[0169] [Table 6]

[0170] project Fields Related information examples Position Class #1 00 First range (e.g., -33,554,432 to -16,777,217) Position Class #2 01 Second range (e.g., -16,777,216 to -1) Position Class #3 10 The third range (0 to 16,777,215) Position Class #4 11 Fourth range (16,777,216~33,554,431)

[0171] Satellite 620 may be configured to indicate one of the four classes to UE 610. When the position information of satellite 620 is assigned to the four classes as shown in Table 6 above, since only 2 bits are required to identify the four classes, the number of bits required to indicate the position state vector of satellite 620 on each axis of the three-dimensional coordinate system can be reduced from 26 bits to 2 bits (2 2 =4). In the above example, an example of using four classes is shown, but more classes can be used. For example, if 64 classes are used, the number of bits required to indicate the position state vector in each axis can be reduced from 26 bits to 6 bits. On the other hand, it can be understood that setting the class does not reduce the resolution of the value representing the position, but simplifies the method of indicating. That is, the operator operating the satellite can set a fixed value to the position within the class range.

[0172] Referring to Table 5, when indicating the velocity of the ephemeris information, approximately 18 bits of information are required for each axis (e.g., x-axis, y-axis, z-axis). As the number of satellites increases, there are many other satellites in orbit around the Earth in addition to the satellites that currently provide service cells for the UE. Therefore, when indicating the velocity, approximately 54 bits are required for each satellite for the xyz coordinate system, which places a burden on the satellites configured to act according to the communication protocol. In order to reduce the burden on system operation and signal processing, specific values ​​can be replaced by using classes. For example, the range of the velocity state vector "VelocityStateVector-r19" is "(-131072…131071)", but can be divided into four classes, as shown in Table 7 below.

[0173] [Table 7]

[0174] project Fields Related information examples Speed ​​Category #1 00 First range (e.g., -131072 to -65,537) Speed ​​Class #2 01 Second range (e.g., -65,536 to -1) Speed ​​Class #3 10 The third range (0 to 65,535) Speed ​​Class #4 11 Fourth range (65,536~131071)

[0175] Satellite 620 can be configured to indicate one of the four classes to UE 610. As a result, the number of bits required to indicate the velocity state vector in each axis (x-axis, y-axis, z-axis) constituting the three-dimensional coordinates can be reduced from 18 bits to 2 bits. In the above example, an example of using four classes is shown, but more classes can be used. For example, if 64 classes are used, the number of bits required to indicate the velocity state vector in each axis can be reduced from 18 bits to 6 bits. On the other hand, it can be understood that setting the class does not reduce the resolution of the value representing the speed, but simplifies the method of indication. That is, the operator operating the satellite can set a fixed value as the speed within the class range.

[0176] Referring to Table 5, when indicating ephemeris information, in order to represent "semiMajorAxis", "eccentricity", "periapsis", "longitude", "inclination" and "meanAnomaly" respectively, as few as 20 bits and as many as 33 bits are required. As the number of satellites increases, in addition to the satellite currently providing a serving cell for the UE, there are many other satellites located in the Earth's orbit. That is, more than 100 bits of information are required to represent the ephemeris information of one satellite. A class of orbital information may be defined to include more simplified information. For example, an orbital class may be defined as shown in Table 8 below.

[0177] [Table 8]

[0178] project Related information examples Track Category #1 First Range Track Class #2 Second range Track Class #3 The third scope Track Class #4 Fourth Scope Track Category #5 Fifth Scope

[0179] Each orbital class may represent one type of a combination of predefined "semiMajorAxis", "eccentricity", "periapsis", "longitude", "inclination", and "meanAnomaly". In the above example, five preset orbital information operated by a satellite operator is designated as an orbital class, and a satellite acting as a gNB (e.g., satellite 620) may inform a terminal (e.g., UE 610) within a cell of one of the orbital classes. As a non-limiting example, a group of multiple satellites, i.e., a satellite group, may be defined according to the orbital class. For example, satellites belonging to the same satellite group may have the same orbital class.

[0180] 3. Group switching information

[0181] like Fig. 7AAs shown, since the satellite moves along a fixed satellite orbit, the switching of the terminal can be expected on the network side. For example, if the satellite is located at an altitude of about 200km from the earth, it is expected that the current satellite (e.g., the first satellite 721) serving a specific area (service cell) will be changed to another satellite (e.g., the second satellite 723) due to the movement on the satellite orbit at a ground speed of about 7.8km / s (4.8mi / s) (28,000km / h (17,000mph)). Moreover, it is expected that a switching process is performed for each terminal located in the specific area. Since the satellite provides a wider coverage area than a general ground base station, a relatively large number of switching processes can be expected compared to the switching in a general base station. Therefore, in one embodiment of the present invention, in order to reduce the excessive signaling that may occur instantaneously in the UE receiving service from the satellite in the ground coverage area (service cell) and reduce congestion, the satellite providing the service cell (e.g., the first satellite 721 and the satellite 620) can provide various information to the terminal. For example, the various information can be illustrated as shown in Table 9 below.

[0182] [Table 9]

[0183]

[0184] Fig. 8AThe system information may include at least one of the information in Table 9. The terminal group in Table 9 may be used to identify the terminal that will perform group switching. The terminal that recognizes that it belongs to the terminal group may prepare for group switching. For example, the terminal may start a timer. According to an embodiment, if the terminal does not belong to the terminal group, the relevant information may be ignored. The satellite ID in Table 9 may represent the ID of the satellite to which the terminal is currently connected. The entity of the operator of the operating network (e.g., AMF 640, satellite 620) may reduce the amount of information required in the switching process by setting a terminal group and operating a timer for each terminal group. The terminals located in a service area may be divided in time to form a group. For example, in a first time interval, the terminals of the first group may perform switching, and in a second time interval after the first time interval, the terminals of the second group may perform switching. The service-related information in Table 9 may be provided for data forwarding (for example, to prevent data transmission interruption that may occur during switching). In Table 9, the switching-related information may include information about a target satellite adjacent to the current source satellite. By notifying the terminal of information about the target satellite in advance, the terminal may be switched. As a non-limiting example, in this example, the satellite ID is fixed, and only the physical satellite responsible for the satellite ID can be changed. Therefore, with a fixed satellite ID, the terminal can be continuously connected. For a satellite that leaves a specific area (e.g., the first satellite 721), the satellite ID can be changed to a new ID, and a satellite that enters the specific area (e.g., the second satellite 723) can reuse the satellite ID used by an existing satellite.

[0185] [Table 10]

[0186]

[0187] Fig. 8A The system information may include at least one of the information in Table 10. The satellite group represents the satellite group mentioned above. For example, satellites having the same orbit may be defined as a satellite group. As another example, satellites connected to the same NTN gateway may be defined as a satellite group. The serving satellite (e.g., satellite 620) providing the current serving cell to the terminal 610 provides the terminal 610 with relevant satellite information in advance in a state where the wireless link is connected, so that even if the serving satellite (e.g., satellite 620) leaves the current serving cell where the terminal 610 is located, information about the satellite (target satellite) serving the serving cell can be notified in advance, so that seamless service can be provided to the UE 610.

[0188] The relevant satellite information in this specification can be determined by at least one of the ephemeris data and constellation data of the satellite predetermined in the system. The terminal ID in Table 10 can represent the terminal information mapped to the satellite constellation and can be omitted according to the situation. The service-related information can be provided for data forwarding (for example, to prevent data transmission interruption that may occur during switching). In Table 10, the switching-related information may include information about a target satellite adjacent to the current source satellite. By notifying the information about the target satellite in advance, the terminal can achieve switching.

[0189] 4. Coverage Information

[0190] In the above example, only information about satellites is provided, but neighboring cells can also be provided from ground base stations in addition to satellites. Therefore, information about the coverage of ground base station services can also be provided to the terminal (e.g., UE 610) for reference. For example, satellite information provided by a non-ground base station (e.g., satellite 620) is as follows.

[0191] [Table 11]

[0192]

[0193] In Table 11, "coverageID" indicates a coverage ID, "referenceLocation" indicates a reference location of a cell provided by a ground base station, and "distanceThresh" indicates a distance from the reference location of the cell. As a non-limiting example, the system information may include not only coverage information but also other information related to the geographical location of the ground base station.

[0194] Just as information about a ground base station is provided by a non-ground base station, information about a non-ground base station may also be provided by a ground base station. According to an embodiment, in addition to the satellite 620, the information provided by Tables 3 to 10 may also be provided by a ground base station (e.g., base station 720). For example, the ground base station may provide at least one of the information illustrated by Tables 3 to 10 to the UE 610 as information of a neighboring cell. The parameters described by Tables 3 to 11 may also be included in the existing system information, rather than in separate system information (e.g., SIBx, SIB19). According to an embodiment, the IEs in Tables 3 to 5 include scheduling of other system information and may be included in SIB1 including configuration information of the serving cell. According to another embodiment, the IEs of Tables 3 to 5 may be included in SIB2 including random access parameters.

[0195] Figure 8BAn example of RRC messages for NTN is shown. Fig. 8A In FIG, system information is shown to transmit cell-specific parameters to terminals within the cell. Figure 8B 8 shows an RRC message 851 defined for sending UE-specific parameters to a specific UE within a cell.

[0196] Reference Figure 8B , the satellite 620 may send an RRC message 851 to the UE 610. The RRC message 851 may include information related to the satellite. The UE 610 may receive the RRC message 851. According to an embodiment, the RRC message 851 may be an RRC establishment message. According to an embodiment, the RRC message 851 may be an RRC recovery message. According to an embodiment, the RRC message may be an RRC reconstruction message. According to an embodiment, the RRC message 851 may be an RRC reconfiguration message.

[0197] The RRC message 851 may include Fig. 8A At least one of the information mentioned in. According to one embodiment, the RRC message 851 may include at least one of "ntn-Config", "t-service", "referenceLocation", "distanceThresh" and "ntn-NeighCellConfigList". According to one embodiment, the RRC message 851 may include at least one of "epochTime", "ntn-UlSyncValidityDuration", "cellSpecificKoffset", "kmac", "ta-Info", "ntn-PolarizationDL", "ntn-PolarizationUL", "ta-Report" and "ephemerisInfo". According to one embodiment, the RRC message 851 may include at least one of "PositionVelocity" and / or "Orbital".

[0198] According to one embodiment, the RRC message 851 may include identification information related to a satellite constellation. The satellite 620 sends an RRC message 851 including identification information to the UE 610, and the identification information is related to a group including the satellite 620 (hereinafter referred to as a satellite constellation). According to one embodiment, satellites orbiting the same orbit may be grouped into the same satellite constellation. For example, satellites in the same satellite constellation may share the same orbit. As an example, satellites in the same satellite constellation may have the same orbital information (e.g., "Orbital-r19" IE) in the ephemeris information. As a non-limiting example, the RRC message 851 may include orbital information specific to a satellite constellation, rather than including orbital information for each satellite.

[0199] According to another embodiment, satellites using the same NTN gateway (e.g., NTN gateway 630) may be grouped into the same group. The NTN gateway may be used at a fixed location on the ground. Therefore, satellites connected to the NTN gateway may be understood to be deployed within a certain distance from the NTN gateway. Therefore, satellites gathered in a specific area may be connected to the NTN gateway together. Since the satellite acts as an independent base station, more than one cell may be provided. Therefore, in addition to the physical cell ID, the satellite may also need to specify a unique ID. For example, in order to identify the satellite, a gNB ID may be utilized.

[0200] As another example, in order to identify the satellite, a gNB-DU ID may be used. As yet another example, in order to identify the satellite, a separately defined ID may be used. The satellite group may be identified by a satellite group ID. For example, a satellite may be identified by the satellite group ID and an intra-group satellite ID. As another example, a satellite may be assigned a separate satellite ID independent of a group. The satellite 620 may transmit the RRC message including information related to the satellite 620 or information about satellites included in the same group as the satellite 620. The UE 610 may identify information about surrounding satellites through identification information of the satellite 620 or identification information of a satellite group to which the satellite 620 belongs.

[0201] According to an embodiment, the RRC message 851 may include class information. As illustrated by Tables 6 to 8, class information may be used to represent a position state vector, a velocity state vector, and / or ephemeris information in a more simplified manner. For example, as shown in Table 6, the satellite 620 may send an RRC message 851 including information indicating a position class to the UE 610. For example, as shown in Table 7, the satellite 620 may send an RRC message 851 including information indicating a velocity class to the UE 610. For example, as shown in Table 8, the satellite 620 may send an RRC message 851 including information indicating an orbit class to the UE 610.

[0202] According to an embodiment, the RRC message 851 may include information related to group switching. For example, the RRC message 851 may include at least one of the items shown in Table 9. And, for example, the RRC message 851 may include at least one of the items shown in Table 10.

[0203] According to an embodiment, the RRC message 851 may include coverage information. The coverage information may include coverage related information of a ground base station adjacent to a satellite providing a service cell. For example, the RRC message 851 may include information indicating a reference position of a cell provided by a ground base station and / or information indicating a distance from a reference position of a cell.

[0204] exist Figure 8B In the example of RRC message 851 provided by satellite 620 to terminal 610, the present disclosure is not limited thereto. The provision of the above information by terminal 610 to satellite 620 can also be understood as an embodiment of the present disclosure.

[0205] FIG. 8A to FIG. 8B An example of information that satellite 620 can provide to terminal 610 is shown. The information can be used to improve the efficiency of the handover process by using a satellite that repeatedly moves on a specified orbit. According to the movement of the satellite, the satellite of the target cell that is the handover object can be predicted. The handover time point can be predicted based on the position and speed of the satellite. Based on various situations, the terminal can prepare for handover in advance, and the handover process within the NTN can be simplified. On the other hand, as the role of the satellite acting as a base station becomes more diverse, according to the deployment scenario of the satellite, 3GPP messages can be used for each interface, and Fig. 8A and Figure 8B The parameters / information mentioned in may be included in existing 3GPP messages.

[0206] FIG. 9A to FIG. 9B An example of signaling over the F1 interface in the NTN is shown.

[0207] Reference Fig.9A In action 901, the gNB-DU 910 may send a first message to the gNB-CU 920 via the F1 interface. The gNB-CU 920 may receive the first message from the gNB-DU 910.

[0208] In action 903, the gNB-CU 920 may send a second message to the gNB-DU 910 via the F1 interface. The gNB-DU 910 may receive the second message from the gNB-CU 920.

[0209] According to one embodiment, the first message may be an F1 setup request message, and the second message may be an F1 setup response message. The gNB-DU 910 may send an F1 setup request message to the gNB-CU 920 through the F1 interface. The gNB-CU 920 may send an F1 setup response message to the gNB-DU 910 through the F1 interface. The F1 setup request message may include at least one of the information in Tables 3 to 11. The F1 setup response message may include at least one of the information in Tables 3 to 11. For example, the first message may include the following IEs illustrated in Tables 12 to 14.

[0210] [Table 12]

[0211]

[0212] 9.3.xxx NTN-Config

[0213] [Table 13]

[0214]

[0215] 9.3.yyy EphemerisInfo

[0216] [Table 14]

[0217]

[0218] According to one embodiment, the first message may be a gNB-DU configuration update message, and the second message may be a gNB-DU configuration update confirmation message. The gNB-DU 910 may send a gNB-DU configuration update message to the gNB-CU 920 through the F1 interface. The gNB-CU 920 may send a gNB-DU configuration update confirmation message to the gNB-DU 910 through the F1 interface. The gNB-DU configuration update message may include at least one of the information in Tables 3 to 11. The gNB-DU configuration update confirmation message may include at least one of the information in Tables 3 to 11. For example, the first message may include the following IE illustrated in Table 15.

[0219] [Table 15]

[0220]

[0221]

[0222] For the IE according to the Table 15, reference may be made to Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0223] According to an embodiment, the first message may be a gNB-DU status indication message. When the first message is a gNB-DU status indication message, transmission of the second message may be omitted. The gNB-DU status indication message may include at least one of the information in Table 3 to Table 11. For example, the first message may include the following IE illustrated in Table 16.

[0224] [Table 16]

[0225]

[0226] For the IE according to the Table 16, reference may be made to Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0227] Reference Fig. 9B In action 951, the gNB-CU 920 may send a first message to the gNB-DU 910 via the F1 interface. The gNB-DU 910 may receive the first message from the gNB-CU 920.

[0228] In action 953, the gNB-DU 910 may send a second message to the gNB-CU 920 via the F1 interface. The gNB-CU 920 may receive the second message from the gNB-DU 910.

[0229] According to an embodiment, the first message may be a gNB-CU configuration update message, and the second message may be a gNB-CU configuration update confirmation message. The gNB-CU 920 may send a gNB-CU configuration update message to the gNB-DU 910 through the F1 interface. The gNB-DU 910 may send a gNB-CU configuration update confirmation message to the gNB-CU 920 through the F1 interface. The gNB-CU configuration update message may include at least one of the information in Tables 3 to 11. The gNB-CU configuration update confirmation message may include at least one of the information in Tables 3 to 11. For example, the first message may include the following IE illustrated in Table 17.

[0230] [Table 17]

[0231]

[0232]

[0233]

[0234] For the IE according to the Table 17, reference may be made to Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0235] According to one embodiment, the first message may be a gNB-DU resource coordination request message, and the second message may be a gNB-DU resource coordination response message. The gNB-CU 920 may send a gNB-DU resource coordination request message to the gNB-DU 910 through the F1 interface. The gNB-DU 910 may send a gNB-DU resource coordination response message to the gNB-CU 920 through the F1 interface. The gNB-DU resource coordination request message may include at least one of the information in Tables 3 to 11. The gNB-DU resource coordination response message may include at least one of the information in Tables 3 to 11. For example, the first message may include the following IE illustrated in Table 18.

[0236] [Table 18]

[0237]

[0238]

[0239] For the IE according to the Table 18, reference may be made to Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0240] Fig.10 An example of signaling through the XN interface in NTN is shown. Fig.10 In the embodiment, the signaling between the non-ground base station and the ground base station is described as an example, but the embodiments of the present disclosure are not limited thereto. Fig.10 The messages on the XN interface described in the specification are transmitted not only between non-ground base stations and ground base stations, but also between non-ground base stations and non-ground base stations or between ground base stations and ground base stations. Fig.10 The message described in the description is described as being first transmitted from the non-ground base station to the ground base station, but is not limited thereto. For example, after the request message is first transmitted from the ground base station to the non-ground base station, the response message may also be transmitted from the non-ground base station to the ground base station. For example, the non-ground base station may include satellite 620. For example, the ground base station may include base station 1020.

[0241] Reference Fig.10 In action 1001, the satellite 620 may send a first message to the base station 1020 through an XN interface. The base station 1020 may receive the first message from the satellite 620.

[0242] In action 1003, the base station 1020 may send a second message to the satellite 620 through the XN interface. The satellite 620 may receive the second message from the base station 1020.

[0243] According to an embodiment, the first message may be a handover request message, and the second message may be a handover response message. The satellite 620 may send a handover request message to the base station 1020 through an XN interface. The base station 1020 may send a handover response message to the satellite 620 through an XN interface. The handover request message may include at least one of the information in Table 3 to Table 11. The handover response message may include at least one of the information in Table 3 to Table 11. For example, the first message may include the following IEs illustrated in Table 19.

[0244] [Table 19]

[0245]

[0246]

[0247]

[0248] For the IE according to the Table 19, reference may be made to the 3GPP TS 38.423 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0249] According to an embodiment, the first message may be a cell activation request message, and the second message may be a cell activation response message. The satellite 620 may send a cell activation request message to the base station 1020 through an XN interface. The base station 1020 may send a cell activation response message to the satellite 620 through an XN interface. The cell activation request message may include at least one of the information in Table 3 to Table 11. The cell activation response message may include at least one of the information in Table 3 to Table 11. For example, the first message may include the following IEs illustrated in Table 20.

[0250] [Table 20]

[0251]

[0252] For the IE according to the Table 20, reference may be made to the 3GPP TS 38.423 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0253] According to an embodiment, the first message may be an XN setup request message, and the second message may be an XN setup response message. The satellite 620 may send an XN setup request message to the base station 1020 through an XN interface. The base station 1020 may send an XN setup response message to the satellite 620 through an XN interface. The XN setup request message may include at least one of the information in Table 3 to Table 11. The XN setup response message may include at least one of the information in Table 3 to Table 11. For example, the first message may include the following IEs illustrated in Table 21.

[0254] [Table 21]

[0255]

[0256]

[0257] For the IE according to the Table 21, reference may be made to the 3GPP TS 38.423 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0258] According to an embodiment, the first message may be a NG-RAN node configuration update message, and the second message may be a NG-RAN node configuration update confirmation message. The satellite 620 may send the NG-RAN node configuration update message to the base station 1020 through the XN interface. The base station 1020 may send the NG-RAN node configuration update confirmation message to the satellite 620 through the XN interface. The NG-RAN node configuration update message may include at least one of the information in Table 3 to Table 11. The NG-RAN node configuration update confirmation message may include at least one of the information in Table 3 to Table 11. For example, the first message may include the following IE illustrated in Table 22.

[0259] [Table 22]

[0260]

[0261]

[0262]

[0263] For the IE according to the Table 22, reference may be made to the 3GPP TS 38.423 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0264] According to an embodiment, the first message may be an S-node add request message, and the second message may be an S-node add response message. The satellite 620 may send an S-node add request message to the base station 1020 through an XN interface. The base station 1020 may send an S-node add response message to the satellite 620 through an XN interface. The S-node add request message may include at least one of the information in Table 3 to Table 11. The S-node add response message may include at least one of the information in Table 3 to Table 11. For example, the first message may include the following IEs illustrated in Table 23.

[0265] [Table 23]

[0266]

[0267]

[0268]

[0269] For the IE according to the Table 23, reference may be made to the 3GPP TS 38.423 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0270] According to an embodiment, the first message may be an S-node modification request message, and the second message may be an S-node modification response message. The satellite 620 may send an S-node modification request message to the base station 1020 through an XN interface. The base station 1020 may send an S-node modification response message to the satellite 620 through an XN interface. The S-node modification request message may include at least one of the information in Table 3 to Table 11. The S-node modification response message may include at least one of the information in Table 3 to Table 11. For example, the first message may include the following IEs illustrated in Table 24.

[0271] [Table 24]

[0272]

[0273]

[0274]

[0275]

[0276] For the IE according to the Table 24, reference may be made to the 3GPP TS 38.423 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0277] According to an embodiment, the first message may be an S-node modification requirement message, and the second message may be an S-node modification confirmation message. The satellite 620 may send the S-node modification requirement message to the base station 1020 through the XN interface. The base station 1020 may send the S-node modification confirmation message to the satellite 620 through the XN interface. The S-node modification requirement message may include at least one of the information in Table 3 to Table 11. The S-node modification confirmation message may include at least one of the information in Table 3 to Table 11. For example, the first message may include the following IEs illustrated in Table 25.

[0278] [Table 25]

[0279]

[0280]

[0281]

[0282] For the IE according to the Table 25, reference may be made to the 3GPP TS 38.423 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0283] FIG. 11A to FIG. 11B An example of signaling through the NG interface in NTN is shown. For the AMF of the NG interface, reference can be made to the description of AMF 235 and AMF 640.

[0284] Reference Fig.11A In action 1101, the satellite 620 may send a first message to the AMF 1120 through an NG interface (e.g., an N2 interface). The AMF 1120 may receive the first message from the satellite 620.

[0285] In action 1103, the AMF 1120 may send a second message to the satellite 620 through an NG interface (e.g., an N2 interface). The satellite 620 may receive the second message from the AMF 1120.

[0286] According to an embodiment, the first message may be a handover requirement message, and the second message may be a handover command message. The satellite 620 may send a handover requirement message to the AMF 1120 through an NG interface (e.g., an N2 interface). The AMF 1120 may send a handover command message to the satellite 620 through an NG interface (e.g., an N2 interface). The handover requirement message may include at least one of the information in Tables 3 to 11. The handover command message may include at least one of the information in Tables 3 to 11. For example, the first message may include the following IEs illustrated in Table 26.

[0287] [Table 26]

[0288]

[0289] For the IE according to the Table 26, reference may be made to the 3GPP TS 38.413 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0290] According to an embodiment, the first message may be a path switch request message, and the second message may be a path switch response message. The satellite 620 may send a path switch request message to the AMF 1120 through an NG interface (e.g., an N2 interface). The AMF 1120 may send a path switch response message to the satellite 620 through an NG interface (e.g., an N2 interface). The path switch request message may include at least one of the information in Tables 3 to 11. The path switch response message may include at least one of the information in Tables 3 to 11. For example, the first message may include the following IEs illustrated in Table 27.

[0291] [Table 27]

[0292]

[0293]

[0294] For the IE according to the Table 27, reference may be made to the 3GPP TS 38.413 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0295] Reference Fig. 11B In action 1151, the AMF 1120 may send a first message to the satellite 620 through an NG interface (e.g., an N2 interface). The satellite 620 may receive the first message from the AMF 1120.

[0296] In action 1153, the satellite 620 may send a second message to the AMF 1120 through an NG interface (e.g., an N2 interface). The AMF 1120 may receive the second message from the satellite 620.

[0297] According to an embodiment, the first message may be a handover request message, and the second message may be a handover response message. The AMF 1120 may send a handover request message to the satellite 620 through an NG interface (e.g., an N2 interface). The satellite 620 may send a handover response message to the AMF 1120 through an NG interface (e.g., an N2 interface). The handover request message may include at least one of the information in Tables 3 to 11. The handover response message may include at least one of the information in Tables 3 to 11. For example, the first message may include the following IEs illustrated in Table 28.

[0298] [Table 28]

[0299]

[0300]

[0301]

[0302] For the IE according to the Table 28, reference may be made to the 3GPP TS 38.413 standard, Table 13 for "NTN-Config" and Table 14 for "EphemerisInfo".

[0303] Fig. 11B The handover request message and the handover response message are shown as examples, but the embodiments of the present disclosure are not limited thereto. In addition to the handover of the cell change, as a message for confirming the mobility of the terminal, a mobility order message and a mobility response message can be used as an embodiment of the present disclosure.

[0304] Fig. 12A An example of a handover process utilizing a regenerative satellite, such as satellite 620, is shown. The handover process may include handover from a non-terrestrial base station to a terrestrial base station, from a terrestrial base station to a non-terrestrial base station, and from a non-terrestrial base station to a non-terrestrial base station.

[0305] Reference Fig. 12AIn action 1201, the satellite 620 may send an RRC configuration message to the UE 610. The RRC configuration message may include measurement configuration information. The RRC configuration message may include, for example, (i) measurement object information, (ii) reporting configuration information, (iii) measurement identity information, (iv) quantity configuration information, and (v) measurement gap information. The measurement object information may indicate an object that the UE 610 will measure.

[0306] Specifically, the measurement object information may indicate at least one of an intra-cell measurement object, an inter-cell measurement object, and an inter-radio access technology (RAT) measurement object. Some of the measurement object information may include identification information related to one or more cells and / or satellites receiving services via satellites. The report configuration information may indicate a report type or a report condition related to when the UE 610 reports a measurement result. Specifically, the report type indicates the type of the measurement result. The report condition may be information related to an event or a cycle for triggering a report of a measurement result in the UE 610. The measurement identifier information may be information related to a measurement identifier, which indicates when and in what type the UE 610 reports on the measurement object by associating the measurement object with the report configuration. The quantitative configuration information may indicate a measurement unit and / or a reporting unit, or may be parameter information for filtering a measurement result value. The measurement gap information may be information related to a measurement gap, which is an interval that the UE 610 can use for measurement without considering data transmission with a serving cell.

[0307] In action 1203, UE 610 may perform measurements. UE 610 may perform measurements on each of more than one cell. The more than one cell may include a serving cell and at least one neighboring cell. The more than one cell may include a cell provided by a satellite and / or a cell provided by a ground base station. UE 610 may perform measurements based on the measurement configuration information. For example, UE 610 may measure cell quality based on a reference signal (e.g., CRS, CSI-RS) and / or a synchronization signal (e.g., SSB) received from a satellite 620. UE 610 may measure the cell quality of a serving cell provided by a satellite 620. UE 610 may measure the cell quality of a neighboring cell of a cell of satellite 620. For example, the cell quality may represent information about a signal associated with a cell. The signal associated with the cell may refer to a signal received by the cell. The cell quality may be information including parameters associated with the signal. For example, the cell quality may be an indicator representing the strength of the signal or an indicator representing the quality of the signal. The parameter associated with the signal may be a parameter selected from the parameters of each signal of a plurality of signals including the signal. For example, the parameter associated with the signal may represent the maximum signal strength value among the signal strength values ​​of each of the plurality of signals. The cell quality may be, for example, a reference signal received power (RSRP), a beam reference signal received power (BRSRP), a reference signal received quality (RSRQ), a received signal strength indicator (RSSI), a signal to interference and noise ratio (SINR), a carrier to interference and noise ratio (CINR), a signal to noise ratio (SNR), an error vector magnitude (EVM), a bit error rate (BER) and a block error rate (BLER) at least one of them. Of course, in addition to the above examples, other terms with equivalent technical meanings or other metrics representing cell quality may also be used. Hereinafter, in the present disclosure, a high cell quality means that a signal quality value related to a signal size is large or a cell quality value related to an error rate is small.A higher cell quality may mean that a smooth wireless communication environment is guaranteed in the cell.

[0308] The UE 610 may generate a measurement report. The measurement report may include a measurement result of the UE 610. The measurement result may include a cell quality of each cell. The measurement result may include identification information of the cell and the cell quality of the cell. For example, the UE 610 may include information related to a neighboring cell that provides a higher signal quality than a serving cell and a measurement result including the cell quality of the neighboring cell in the measurement report. According to an embodiment, when the cell is served by a satellite, the UE 610 may further include information related to the satellite (e.g., satellite ID, satellite group ID, location information, orbital ID) in the measurement report.

[0309] In action 1205, UE 610 may send a measurement report to satellite 620. For example, UE 610 may perform measurement reporting periodically. For example, UE 610 may perform measurement reporting based on an event. When a trigger condition set in the measurement configuration information is met, UE 610 may perform the measurement reporting. As an example, if the channel quality of the serving cell provided by satellite 620 is lower than the channel quality of the neighboring cell, UE 610 may send a measurement report to satellite 620.

[0310] In action 1207, the satellite 620 may identify a target cell. The satellite 620 may identify a target cell as a handover object based on the measurement report and / or a policy. According to an embodiment, the satellite 620 may identify a target cell indicated by the measurement report. The target cell may be provided by another satellite or by a ground base station. Fig. 12A , it is shown that the target cell is identified after receiving the measurement report, but the embodiments of the present disclosure are not limited to this. Independent of the measurement report, the satellite 620 can also identify the predetermined target cell based on the satellite moving along the specified orbit. The predetermined target cell can be provided by a satellite adjacent to the satellite 620. The satellite can be configured to serve the area served by the satellite 620 during the first time interval in a second time interval different from the first time interval. The second time interval may partially overlap with the first time interval. The satellite 620 can identify the target cell based on the information of the satellite and according to a value set in a core network entity (e.g., AMF 1120) or an internal memory.

[0311] In action 1209, the satellite 620 may send a handover command to the UE 610. The satellite 620 may send a handover command including information indicating the target cell to the UE 610. For example, the satellite 620 may send an RRC reconfiguration message to the UE 610. The RRC reconfiguration message may be used to indicate a handover to the target cell. For example, the RRC reconfiguration message may include a "Reconfiguration with sync" IE. The RRC reconfiguration message may include information related to the target cell. According to an embodiment, when the target cell is provided by a satellite, the RRC reconfiguration message may also include information related to the satellite providing the target cell. For example, the information related to the satellite may include NTN related information (e.g., information in Table 3), NTN configuration information (e.g., NTN-Config IE) and / or ephemeris information (e.g., EphemerisInfo IE).

[0312] Fig. 12B An example of cell selection utilizing a regenerative satellite (eg, satellite 620) is shown. The cell selection may include cell selection and / or cell reselection.

[0313] Reference Fig. 12B In action 1251, UE 610 may receive a downlink signal (e.g., CRS / SSB). UE 610 may perform measurement based on the downlink signal. UE 610 may perform measurement based on a cell-specific downlink signal. UE 610 may obtain cell quality of each cell. The cell as a measurement object may include a cell provided by a satellite and / or a cell provided by a ground base station.

[0314] In action 1253, UE 610 may select a cell. UE 610 may perform measurement based on a downlink signal. UE 610 may select a cell based on the measurement result. For example, when the cell quality of a cell exceeds a threshold, UE 610 may camp on the cell. UE 610 may receive system information (e.g., MIB, SIB1) from the cell. UE 610 may initiate an access procedure to the cell based on the system information.

[0315] In action 1255, the UE 610 may perform an initial access procedure. The UE 610 may perform a cell access procedure to access the cell. For example, the UE 610 may perform a RACH procedure (e.g., random access preamble transmission, random access response reception, Msg 3 transmission (RRC Setup Request), and Msg 4 reception (Contention resolution)) (RRC Setup) based on the system information. If the cell to be accessed is provided by a satellite, the UE 610 may omit at least a portion of the RACH procedure.

[0316] pass FIG. 12A to FIG. 12B The selection of the described cell, in addition to the signal quality such as RSRP, can also be determined by considering the inherent characteristics of the satellite as a non-ground base station (hereinafter, satellite characteristics). The satellite characteristics may include various factors. For example, the satellite characteristics may include at least one of the mobility of the satellite, the coverage characteristics of serving a relatively wide geographical range, and the predictability of moving on a specified orbit. The mobility or predictability of the satellite can be quantified by defining satellites moving on the same orbit or serving the same area as a group. Therefore, in addition to the signal quality such as RSRP, the cell selection can be based on information related to the group to which the satellite belongs (e.g., a specific orbit, a specific NTN gateway), the ephemeris information of the satellite (e.g., EphemerisInfo IE), and / or at least one of the information related to the distance or communication time (e.g., TA) between the satellite and the UE 610 located on the ground. In addition to the signal quality, the cell quality used in the triggering conditions of the measurement report of the specification (e.g., comparing the cell quality with a threshold, comparing the cell quality of the serving cell with the cell quality of a neighboring cell) or the triggering conditions in the conditional switching (e.g., comparing the cell quality with a threshold, comparing the cell quality of the serving cell with the cell quality of a neighboring cell) can also be determined based on at least one of the factors.

[0317] Fig.13 Examples of components of a satellite (eg, satellite 260, satellite 620) are shown. Terms such as "unit" and "device" used below refer to a unit that processes at least one function or action, which can be implemented by hardware or software or a combination of hardware and software.

[0318] Reference Fig.13, the satellite 620 may include a transceiver 1301, a processor 1303, and a memory 1305. The transceiver 1301 performs a function for transmitting and receiving signals through a wireless channel. For example, the transceiver 1301 uplinks a baseband signal into an RF band signal and transmits it through an antenna, and downlinks the RF band signal received through the antenna into a baseband signal. For example, the transceiver 1301 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

[0319] The transceiver 1301 may include multiple transceiver paths. Further, the transceiver 1301 may include an antenna unit. The transceiver 1301 may include at least one antenna array consisting of multiple antenna elements. From a hardware perspective, the transceiver 1301 may be composed of digital circuits and analog circuits (e.g., radio frequency integrated circuits (RFIC)). Here, the digital circuits and the analog circuits may be implemented in one package. Furthermore, the transceiver 1301 may include multiple RF chains. The transceiver 1301 may perform beamforming. In order to give the signal to be transmitted and received a directionality corresponding to the setting of the processor 1303, the transceiver 1301 may apply a beamforming weighting value to the signal. According to one embodiment, the transceiver 1301 may include an RF block (or RF unit).

[0320] The transceiver 1301 may transmit and receive signals on a radio access network. For example, the transceiver 1301 may transmit a downlink signal. The downlink signal may include a synchronization signal (SS), a reference signal (RS) (e.g., a cell-specific reference signal (CRS), a demodulation reference signal (DM (demodulation)-RS)), system information (e.g., MIB, SIB, remaining system information (RMSI), other system information (OSI)), a configuration message, control information or downlink data, etc. And, for example, the transceiver 1301 may receive an uplink signal. The uplink signal may include a random access associated signal (e.g., a random access preamble (RAP) (or message 1 (Msg1)), a message 3 (Msg3), a reference signal (e.g., a sounding reference signal (SRS), DM-RS) or a power headroom report (PHR). Fig.13 Only transceiver 1301 is shown in FIG. 6 , but according to other implementation examples, satellite 620 may include more than two RF transceivers.

[0321] The processor 1303 controls the overall operation of the satellite 620. The processor 1303 may be referred to as a control unit. For example, the processor 1303 transmits and receives signals through the transceiver 1301. Also, the processor 1303 records and reads data in the memory 1305. In addition, the processor 1303 may execute the functions of the protocol stack required in the communication specification. Fig.13 Only the processor 1303 is shown in the figure, and according to other implementation examples, the satellite 620 may include more than two processors. In the processor 1303, the instruction set or code stored in the memory 1305 may be an instruction / code or a storage space storing instructions / code that is at least temporarily resident in the processor 1303, or a part of the circuitry of the processor 1303. In addition, the processor 1303 may include various modules for performing communication. The processor 1303 may control the satellite 620 to make it perform the actions of the embodiment.

[0322] The memory 1305 stores data such as basic programs, application programs, setting information, etc. for the operation of the satellite 620. The memory 1305 may be referred to as a storage unit. The memory 1305 may be composed of a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. In addition, the memory 1305 provides the stored data according to a request of the processor 1303. According to an embodiment, the memory 1305 may include a memory for conditions, instructions, or setting values ​​associated with the SRS transmission method.

[0323] Fig.14 An example of constituent elements of a terminal (e.g., UE 610) is shown. The terminal illustrates UE 610. UE 610 can be connected to a gNB (e.g., gNB 120) that provides NR access through NTN.

[0324] Reference Fig.14 , the UE 610 may include at least one processor 1401, at least one memory 1403, and at least one transceiver 1405. In the following, although a constituent element is described in the singular, implementation of a plurality of constituent elements or sub-constituent elements is not excluded.

[0325] The processor 1401 controls the overall actions of the UE 610. For example, the processor 1401 records data in the memory 1403 and reads it. For example, the processor 1401 sends and receives signals through the transceiver 1405. Fig.14 A processor is shown in the figure, but the embodiments of the present disclosure are not limited thereto. The UE 610 may include at least one processor in order to execute the embodiments of the present disclosure. The processor 1401 may be referred to as a control unit or a control means. According to the embodiment, the processor 1401 may control the UE 610 to execute at least one of the actions or methods of the embodiments of the present disclosure.

[0326] The memory 1403 may store data such as basic programs, applications, setting information, etc. used for the actions of the UE 610. The memory 1403 may store various data used by at least one constituent element (e.g., transceiver 1405, processor 1401). The data may include, for example, input data or output data about software and its related instructions. The memory 1403 may be composed of a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. In addition, the memory 1403 may provide the stored data according to the request of the processor 1401.

[0327] The transceiver 1405 performs functions for transmitting and receiving signals through a wireless channel. For example, the transceiver 1405 performs a conversion function between a baseband signal and a bit string according to the physical layer specification of the system. For example, when transmitting data, the transceiver 1405 encodes and modulates the transmission bit string to generate a complex value symbol. And, when receiving data, the transceiver 1405 restores the received bit string by demodulating and decoding the baseband signal. And, the transceiver 1405 up-converts the baseband signal into an RF band signal and transmits it through the antenna, and down-converts the RF band signal received through the antenna into a baseband signal.

[0328] To this end, the transceiver 1405 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter (ADC), etc. In addition, the transceiver 1405 may include multiple transceiver paths. Further, the transceiver 1405 may include at least one antenna array consisting of multiple antenna elements. From a hardware perspective, the transceiver 1405 may be composed of a digital unit and an analog unit, and the analog unit may be composed of multiple sub-units according to the operating power, operating frequency, etc.

[0329] The transceiver 1405 sends and receives signals as described above. Therefore, the transceiver 1405 may be referred to as a "sending unit", a "receiving unit" or a "transceiver unit". Furthermore, in the following description, the sending and receiving performed through a wireless channel, a backhaul network, an optical cable, an Ethernet, or other wired paths are used to include the meaning of the processing performed by the transceiver 1405 as described above. According to one embodiment, the transceiver 1405 may provide an interface for performing communication with other nodes within the network. That is, the transceiver 1405 may convert a bit string sent from the UE 610 to other nodes (e.g., other access nodes, other base stations, upper nodes, core networks, etc.) into a physical signal, and convert a physical signal received from other nodes into a bit string.

[0330] When describing the embodiments of the present disclosure, the terms and messages defined in 3GPP are used to describe the messages between the satellite (e.g., satellite 620) and the terminal (e.g., UE 610), but the embodiments of the present disclosure are not limited thereto. Of course, terms and messages having the same technical meanings as the above terms and messages may be used instead. In addition, as a satellite, not only gNB, gNB-CU, gNB-DU, but also gNB-CU-CP (control plane) (e.g., Figure 3A C-plane) and gNB-CU-UP (user plane) (e.g., Figure 3BU-plane)). Furthermore, a satellite can be used not only as a base station (e.g., gNB) or a part of a base station (e.g., DU), but also a core network entity (e.g., AMF 235) connected to the base station can be implemented as a satellite. For example, communication between a satellite and a satellite 620 as an AMF 235 action can also be defined. For example, a logical node including an AMF 235 and a gNB 120 can be implemented in one satellite. As implemented in software through network virtualization, separate logical nodes can be deployed within one hardware satellite.

[0331] In an embodiment, a satellite device for providing NTN access is provided. The satellite device for providing NTN access may include at least one processor and at least one transceiver. The at least one processor may be configured to send a message including handover related information to a terminal on a cell provided by the satellite through the at least one transceiver. The handover related information may include information related to the group to which the satellite belongs, information related to a target satellite of a target cell for handover of the terminal, information related to a terminal group to which the terminal belongs, information related to a condition of conditional handover of the terminal, and information related to at least one of the position, velocity, and orbit of the target satellite.

[0332] According to one embodiment, the message may include at least one of position-type information for indicating the position of the satellite or the target satellite, speed-type information for indicating the speed of the satellite or the target satellite, and orbit-type information for indicating the orbit of the satellite or the target satellite.

[0333] According to an embodiment, the satellite device for providing NTN access may be configured to receive a switching request message from the AMF through the at least one transceiver. The switching request message may include at least one of a satellite ID for the target satellite, a satellite group ID of a satellite group to which the target satellite belongs, orbit information of the target satellite, position information of the target satellite, speed information of the target satellite, TA information of the target satellite, effective time information of the target satellite, polarization information of the target satellite, and scheduling offset information of the target satellite.

[0334] According to one embodiment, the message may include an event type for the conditional switching and at least one parameter for the event type. The message may include effective time information for the terminal group to which the terminal belongs, and the effective time information may be used to indicate a time interval for the terminals in the terminal group to perform the conditional switching.

[0335] According to an embodiment, the at least one processor may be configured to receive a switching command message from the AMF through the at least one transceiver. The switching command message may include at least one of a satellite ID for the target satellite, a satellite group ID of a satellite group to which the target satellite belongs, orbit information of the target satellite, position information of the target satellite, speed information of the target satellite, TA information of the target satellite, effective time information of the target satellite, polarization information of the target satellite, and scheduling offset information of the target satellite.

[0336] According to an embodiment, the at least one processor may be configured to send a switching requirement message to the AMF through the at least one transceiver. The switching requirement message may include at least one of a satellite ID for the target satellite, a satellite group ID of a satellite group to which the target satellite belongs, orbit information of the target satellite, position information of the target satellite, speed information of the target satellite, TA information of the target satellite, effective time information of the target satellite, polarization information of the target satellite, and scheduling offset information of the target satellite.

[0337] According to one embodiment, the at least one processor may be configured to: determine the switching of the target satellite to the target cell; send a switching command message to the target satellite through the at least one transceiver; and receive a switching response message from the target satellite through the at least one transceiver.

[0338] According to an embodiment, the at least one processor may be configured to: send a message including measurement configuration information to the terminal through the at least one transceiver; and receive a measurement report message according to the measurement configuration information from the terminal through the at least one transceiver. The measurement configuration information may include information related to the measurement of each of more than one cell. The measurement report message may include the cell quality of the cell provided by the satellite. The cell quality may be determined based on at least one of the signal quality, the orbit of the satellite, the satellite constellation to which the satellite belongs, the distance between the satellite and the terminal, and the TA information of the satellite.

[0339] According to one embodiment, the at least one processor may be configured to: send a gNB-DU configuration update message to the gNB-CU through the F1 interface by the at least one transceiver; and receive a gNB-DU configuration update confirmation message from the gNB-CU through the F1 interface by the at least one transceiver. The gNB-DU configuration update message may include at least one of information related to one or more cells provided by the satellite, information related to the orbit of the satellite, information related to the satellite constellation to which the satellite belongs, information related to the speed of the satellite, information related to the service time of the satellite, and information related to the capabilities of the satellite. The satellite may be associated with a protocol of a physical layer, a protocol of a medium access control layer, and a protocol of a radio link control layer, and the gNB-CU may be associated with a protocol of a radio resource control layer and a protocol of a packet data convergence protocol layer.

[0340] According to an embodiment, the at least one processor may be configured to broadcast system information on a cell provided by the satellite through the at least one transceiver. The system information may include at least one of information related to a satellite constellation to which the satellite belongs, information related to an orbit of the satellite constellation, information related to a cell of each satellite belonging to the satellite constellation, and information related to an NTN gateway associated with the satellite constellation.

[0341] In an embodiment, a method performed by a satellite for providing NTN access is provided. The method may include the following steps: sending a message including handover related information to a terminal on a cell provided by the satellite. The handover related information may include information related to the group to which the satellite belongs, information related to a target satellite of a target cell for handover of the terminal, information related to a terminal group to which the terminal belongs, information related to a condition of conditional handover of the terminal, and information related to at least one of the position, velocity, and orbit of the target satellite.

[0342] According to one embodiment, the message may include at least one of position-type information for indicating the position of the satellite or the target satellite, speed-type information for indicating the speed of the satellite or the target satellite, and orbit-type information for indicating the orbit of the satellite or the target satellite.

[0343] According to an embodiment, the method may include the following steps: receiving a switching request message from an AMF. The switching request message may include at least one of a satellite ID for the target satellite, a satellite group ID of a satellite group to which the target satellite belongs, orbit information of the target satellite, position information of the target satellite, speed information of the target satellite, TA information of the target satellite, effective time information of the target satellite, polarization information of the target satellite, and scheduling offset information of the target satellite.

[0344] According to an embodiment, the message may include an event type for the conditional switching and at least one parameter for the event type. The message may include effective time information for the terminal group to which the terminal belongs. The effective time information may be used to indicate a time interval for the terminal in the terminal group to perform the conditional switching.

[0345] According to an embodiment, the method may include the following steps: receiving a switching command message from an AMF. The switching command message may include at least one of a satellite ID for the target satellite, a satellite group ID of a satellite group to which the target satellite belongs, orbit information of the target satellite, position information of the target satellite, speed information of the target satellite, TA information of the target satellite, effective time information of the target satellite, polarization information of the target satellite, and scheduling offset information of the target satellite.

[0346] According to an embodiment, the method may include the following steps: sending a switching request message to the AMF. The switching request message may include at least one of a satellite ID for the target satellite, a satellite group ID of a satellite group to which the target satellite belongs, orbit information of the target satellite, position information of the target satellite, speed information of the target satellite, TA information of the target satellite, effective time information of the target satellite, polarization information of the target satellite, and scheduling offset information of the target satellite.

[0347] According to an embodiment, the method may include the following steps: determining a handover from the target satellite to the target cell; sending a handover command message to the target satellite; and receiving a handover response message from the target satellite.

[0348] According to an embodiment, the method may include the following steps: sending a message including measurement configuration information to the terminal; and receiving a measurement report message according to the measurement configuration information from the terminal. The measurement configuration information may include information related to the measurement of each of more than one cell. The measurement report message may include the cell quality of the cell provided by the satellite. The cell quality may be determined based on at least one of signal quality, the orbit of the satellite, the satellite constellation to which the satellite belongs, the distance between the satellite and the terminal, and TA information of the satellite.

[0349] According to an embodiment, the method may include the following steps: sending a gNB-DU configuration update message to the gNB-CU through the F1 interface by the at least one transceiver; and receiving a gNB-DU configuration update confirmation message from the gNB-CU through the F1 interface. The gNB-DU configuration update message may include at least one of information related to one or more cells provided by the satellite, information related to the orbit of the satellite, information related to the satellite constellation to which the satellite belongs, information related to the speed of the satellite, information related to the service time of the satellite, and information related to the capabilities of the satellite. The satellite may be associated with a protocol of a physical layer, a protocol of a medium access control layer, and a protocol of a radio link control layer, and the gNB-CU may be associated with a protocol of a radio resource control layer and a protocol of a packet data convergence protocol layer.

[0350] According to an embodiment, the method may include the step of broadcasting system information on a cell provided by the satellite by the at least one transceiver. The system information may include at least one of information related to a satellite constellation to which the satellite belongs, information related to an orbit of the satellite constellation, information related to a cell of each satellite belonging to the satellite constellation, and information related to an NTN gateway associated with the satellite constellation.

[0351] In an embodiment, a non-transitory recording medium is provided. The non-transitory recording medium may include a memory for storing instructions. When the instructions are executed by at least one processor, a satellite for providing NTN access performs the following operations: sending a message including handover related information to a terminal on a cell provided by the satellite, wherein the handover related information may include information related to a group to which the satellite belongs, information related to a target satellite of a target cell for handover of the terminal, information related to a terminal group to which the terminal belongs, information related to a condition of conditional handover of the terminal, and information related to at least one of a position, a velocity, and an orbit of the target satellite.

[0352] The methods of the embodiments described in the claims or the specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0353] In the case of software implementation, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured to be executable by one or more processors in the electronic device. The one or more programs include instructions for causing the electronic device to implement the method of the embodiment described in the claims or specification of the present disclosure.

[0354] Such a program (software module, software) may be stored in a non-volatile memory including a random access memory, a flash memory, a read only memory (ROM), an electrically erasable programmable read only memory (EEPROM), a magnetic disc storage device, a compact disc-ROM (CD-ROM), a digital versatile disc (DVDs) or other forms of optical storage devices, a magnetic cassette. Alternatively, it may be stored in a memory composed of a combination of part or all of them. Furthermore, each constituent memory may include a plurality of them.

[0355] Furthermore, the program may be stored in an attachable storage device that can be accessed through a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN), or a combination thereof. Such a storage device may be accessed to the device for executing the embodiments of the present disclosure through an external port. Furthermore, an additional storage device on the communication network may also be accessed to the device for executing the embodiments of the present disclosure.

[0356] In the above-mentioned specific embodiments of the present disclosure, the constituent elements included in the present disclosure are expressed as singular or plural according to the specific embodiments proposed. However, the expression of singular or plural is selected for convenience of explanation and is suitable for the proposed situation. The present disclosure is not limited to singular or plural constituent elements, and even if the constituent element is expressed as plural, it can also be constituted as singular, or even if the constituent element is expressed as singular, it can also be constituted as plural.

[0357] In addition, although the above description of the present disclosure is described with respect to specific embodiments, various modifications may be implemented without departing from the scope of the present disclosure.

Claims

1. A satellite device for providing access to a non-terrestrial network (NTN), wherein: include: at least one processor; as well as at least one transceiver, The at least one processor is configured to send, through the at least one transceiver, a message including handover related information to a terminal on a cell provided by the satellite, The switching-related information includes information related to the group to which the satellite belongs, information related to a target satellite of a target cell for switching of the terminal, information related to a terminal group to which the terminal belongs, information related to conditions for conditional switching of the terminal, and at least one of information related to at least one of the position, velocity and orbit of the target satellite.

2. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The message includes at least one of position information for indicating the position of the satellite or the target satellite, speed information for indicating the speed of the satellite or the target satellite, and orbit information for indicating the orbit of the satellite or the target satellite.

3. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The at least one processor is configured to receive, through the at least one transceiver, a handover request message from an access and mobility management function (AMF), The switching request message includes at least one of the satellite ID for the target satellite, the satellite group ID of the satellite group to which the target satellite belongs, the orbit information of the target satellite, the position information of the target satellite, the speed information of the target satellite, the timing advance TA information of the target satellite, the effective time information of the target satellite, the polarization information of the target satellite and the scheduling offset information of the target satellite.

4. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The message includes an event type for the conditional switching and at least one parameter for the event type, The message includes valid time information for the terminal group to which the terminal belongs, The effective time information is used to indicate a time interval for terminals in the terminal group to perform the conditional switching.

5. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The at least one processor is configured to receive a handover command message from an access and mobility management function (AMF) via the at least one transceiver, The switching command message includes at least one of the satellite ID for the target satellite, the satellite group ID of the satellite group to which the target satellite belongs, the orbit information of the target satellite, the position information of the target satellite, the speed information of the target satellite, the timing advance TA information of the target satellite, the effective time information of the target satellite, the polarization information of the target satellite, and the scheduling offset information of the target satellite.

6. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The at least one processor is configured to send a handover required message to an access and mobility management function AMF through the at least one transceiver, The switching request message includes at least one of the satellite ID for the target satellite, the satellite group ID of the satellite group to which the target satellite belongs, the orbit information of the target satellite, the position information of the target satellite, the speed information of the target satellite, the timing advance TA information of the target satellite, the effective time information of the target satellite, the polarization information of the target satellite, and the scheduling offset information of the target satellite.

7. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The at least one processor is configured to: Determining a handover of the target satellite to the target cell; sending a handover command message to the target satellite via the at least one transceiver; A handoff response message is received from the target satellite via the at least one transceiver.

8. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The at least one processor is configured to: sending, by the at least one transceiver, a message including measurement configuration information to the terminal; receiving, by the at least one transceiver, a measurement report message according to the measurement configuration information from the terminal, The measurement configuration information includes information related to measurement of each of the more than one cells, The measurement report message includes the cell quality of the cell provided by the satellite, The cell quality is determined based on at least one of a signal quality, an orbit of the satellite, a satellite constellation to which the satellite belongs, a distance between the satellite and the terminal, and timing advance TA information of the satellite.

9. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The at least one processor is configured to: Sending, by the at least one transceiver, a next generation Node B-distributed unit gNB-DU configuration update message to the next generation Node B-centralized unit gNB-CU through the F1 interface; receiving, by the at least one transceiver, a gNB-DU configuration update confirm message from the gNB-CU through the F1 interface, The gNB-DU configuration update message includes at least one of information related to one or more cells provided by the satellite, information related to an orbit of the satellite, information related to a satellite constellation to which the satellite belongs, information related to a speed of the satellite, information related to a service time of the satellite, and information related to capabilities of the satellite, The satellite is associated with a protocol of a physical layer, a protocol of a medium access control layer, and a protocol of a radio link control layer, and the gNB-CU is associated with a protocol of a radio resource control layer and a protocol of a packet data convergence protocol layer.

10. The satellite device for providing access to a non-terrestrial network (NTN) according to claim 1, wherein: The at least one processor is configured to broadcast system information over a cell provided by the satellite via the at least one transceiver, The system information includes at least one of information related to a satellite constellation to which the satellite belongs, information related to an orbit of the satellite constellation, information related to a cell of each satellite belonging to the satellite constellation, and information related to an NTN gateway associated with the satellite constellation.

11. A method performed by a satellite for providing access to a non-terrestrial network (NTN), wherein: The steps include: sending a message including handover related information to a terminal in a cell provided by the satellite, The switching-related information includes information related to the group to which the satellite belongs, information related to a target satellite of a target cell for switching of the terminal, information related to a terminal group to which the terminal belongs, information related to conditions for conditional switching of the terminal, and at least one of information related to at least one of the position, velocity and orbit of the target satellite.

12. The method performed by a satellite for providing access to a non-terrestrial network (NTN) according to claim 11, wherein: The message includes at least one of position information for indicating the position of the satellite or the target satellite, speed information for indicating the speed of the satellite or the target satellite, and orbit information for indicating the orbit of the satellite or the target satellite.

13. The method performed by a satellite for providing access to a non-terrestrial network (NTN) according to claim 11, wherein: The steps include: Receive a Handover Request message from the Access and Mobility Management Function AMF, The switching request message includes at least one of the satellite ID for the target satellite, the satellite group ID of the satellite group to which the target satellite belongs, the orbit information of the target satellite, the position information of the target satellite, the speed information of the target satellite, the timing advance TA information of the target satellite, the effective time information of the target satellite, the polarization information of the target satellite and the scheduling offset information of the target satellite.

14. The method performed by a satellite for providing access to a non-terrestrial network (NTN) according to claim 11, wherein: The message includes an event type for the conditional switching and at least one parameter for the event type, The message includes valid time information for the terminal group to which the terminal belongs, The effective time information is used to indicate a time interval for terminals in the terminal group to perform the conditional switching.

15. The method performed by a satellite for providing access to a non-terrestrial network (NTN) according to claim 11, wherein: The steps include: Receive a handover command message from the access and mobility management function AMF, The switching command message includes at least one of the satellite ID for the target satellite, the satellite group ID of the satellite group to which the target satellite belongs, the orbit information of the target satellite, the position information of the target satellite, the speed information of the target satellite, the timing advance TA information of the target satellite, the effective time information of the target satellite, the polarization information of the target satellite, and the scheduling offset information of the target satellite.

16. The method performed by a satellite for providing access to a non-terrestrial network (NTN) according to claim 11, wherein: The steps include: Send a handover request message to the access and mobility management function AMF, The switching request message includes at least one of the satellite ID for the target satellite, the satellite group ID of the satellite group to which the target satellite belongs, the orbit information of the target satellite, the position information of the target satellite, the speed information of the target satellite, the timing advance TA information of the target satellite, the effective time information of the target satellite, the polarization information of the target satellite, and the scheduling offset information of the target satellite.

17. The method according to claim 11, performed by a satellite for providing access to a non-terrestrial network (NTN), comprising the steps of: Determining a handover of the target satellite to the target cell; sending a handover command message to the target satellite; and A handoff response message is received from the target satellite.

18. The method performed by a satellite for providing access to a non-terrestrial network (NTN) according to claim 11, wherein: The steps include: sending a message including measurement configuration information to the terminal; and receiving a measurement report message according to the measurement configuration information from the terminal, The measurement configuration information includes information related to measurement of each of the more than one cells, The measurement report message includes the cell quality of the cell provided by the satellite, The cell quality is determined based on at least one of a signal quality, an orbit of the satellite, a satellite constellation to which the satellite belongs, a distance between the satellite and the terminal, and timing advance TA information of the satellite.

19. The method performed by a satellite for providing access to a non-terrestrial network (NTN) according to claim 11, wherein: The steps include: Sending, by the at least one transceiver, a next generation Node B-distributed unit gNB-DU configuration update message to the next generation Node B-centralized unit gNB-CU through the F1 interface; and receiving a gNB-DU configuration update confirmation message from the gNB-CU via the F1 interface, The gNB-DU configuration update message includes at least one of information related to one or more cells provided by the satellite, information related to an orbit of the satellite, information related to a satellite constellation to which the satellite belongs, information related to a speed of the satellite, information related to a service time of the satellite, and information related to capabilities of the satellite, The satellite is associated with a protocol of a physical layer, a protocol of a medium access control layer, and a protocol of a radio link control layer, and the gNB-CU is associated with a protocol of a radio resource control layer and a protocol of a packet data convergence protocol layer.

20. The method performed by a satellite for providing access to a non-terrestrial network (NTN) according to claim 11, wherein: The steps include: broadcasting, by the at least one transceiver, system information over a cell provided by the satellite, The system information includes at least one of information related to a satellite constellation to which the satellite belongs, information related to an orbit of the satellite constellation, information related to a cell of each satellite belonging to the satellite constellation, and information related to an NTN gateway associated with the satellite constellation.

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