Apparatus and method for power saving in non-terrestrial network

Abstract

To provide an apparatus and method for power saving in a non-terrestrial network (NTN).SOLUTION: In embodiments, an apparatus (AMF 235) of a satellite for providing a non-terrestrial network (NTN) 200 access transmits, to a terminal 110 through at least one transceiver (gNB120), a message including information indicating whether transform precoding of downlink transmission is activated, generates downlink signals based on the information, and transmits, to the terminal through the at least one transceiver, the downlink signals. In a case that the information indicates that the transform precoding is activated, the downlink signals are generated through a DFT-S OFDM scheme, and in a case that the information does not indicate that the transform precoding is activated, the downlink signals are generated through a CP-OFDM scheme.SELECTED DRAWING: Figure 2a

Description

Technical Field

[0001] The present disclosure generally relates to a non-terrestrial network (NTN) that provides wireless communication services through satellites located in Earth orbit rather than terrestrial base stations or aerial platforms flying at high altitudes. More specifically, it relates to devices and methods for power saving in non-terrestrial networks.

Background Art

[0002] A non-terrestrial network (NTN) has been introduced to complement terrestrial networks that provide wireless communication systems. The non-terrestrial network can provide communication services even in areas where it is difficult to construct a terrestrial network or in disaster situations. Also, due to the recent decrease in satellite launch costs, an efficient access network environment can be provided.

Summary of the Invention

Means for Solving the Problems

[0003] In an embodiment, a satellite device for providing NTN access is provided. The device can include a memory containing instructions, at least one processor, and at least one transceiver. When the instructions are executed by the at least one processor, the device can transmit a message containing information indicating whether to activate transform precoding for downlink transmission through the at least one transceiver to a terminal, generate a downlink signal based on the information, and cause the downlink signal to be transmitted to the terminal through the at least one transceiver. When the information indicates activation of the transform precoding, the downlink signal is generated through a DFT-S (discrete fourier transform-spreading) OFDM (orthogonal frequency division multiplexing) scheme, and when the information does not indicate activation of the transform precoding, the downlink signal can be generated through a CP (cyclic prefix)-OFDM scheme.

[0004] In an embodiment, a terminal for communicating with a satellite via NTN access is provided. The terminal may include a memory containing instructions, at least one processor, and at least one transceiver. When the instructions are executed by the at least one processor, the terminal device can receive, through the at least one transceiver, a message from the satellite that includes information indicating whether to activate transform precoding for downlink transmission, and based on the information, cause the downlink signal to be received from the satellite through the at least one transceiver. When the information indicates activation of the transform precoding, the downlink signal may be received through the DFT-S (discrete fourier transform-spreading) OFDM (orthogonal frequency division multiplexing) scheme. When the information does not indicate activation of the transform precoding, the downlink signal may be received through the CP (cyclic prefix)-OFDM scheme.

[0005] In an embodiment, a network device for performing communication with a satellite for providing NTN access is provided. The network device may include a memory containing instructions, at least one processor, and at least one transceiver. When the instructions are executed by the at least one processor, the network device can identify a plurality of satellites corresponding to sectors related to a specific area, identify a first satellite to be deactivated among the plurality of satellites based on prediction information related to a specific time, and cause a message instructing the deactivation of the first satellite to be transmitted to the first satellite through the at least one transceiver.

[0006] In an embodiment, a satellite device for providing NTN access is provided. The device can include a memory containing instructions, at least one processor, and at least one transceiver. When the instructions are executed by the at least one processor, the satellite can receive, via the at least one transceiver, a message from a network device instructing the deactivation of the satellite, and in response to the message, cause at least one of the components of the satellite to be deactivated. The deactivation of the satellite may be related to a specific area and a specific time.

Brief Description of the Drawings

[0007]

Figure 1

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Modes for Carrying Out the Invention

[0008] The terms used in this disclosure are merely used to describe specific embodiments and are not intended to limit the scope of other embodiments. Singular expressions can include plural expressions unless the context clearly indicates otherwise. The terms used herein, including technical or scientific terms, can have the same meaning as commonly understood by those of ordinary skill in the technical field described in this disclosure. Among the terms used in this disclosure, terms defined in a general dictionary can be interpreted in the same or similar meaning as their meaning in the context of the related art, and unless clearly defined in this disclosure, they are not interpreted in an ideal or overly formal sense. In some cases, even terms defined in this disclosure cannot be interpreted in a way that excludes the embodiments of this disclosure.

[0009] In various embodiments of the present disclosure described below, a hardware-based access method will be described as an example. However, since various embodiments of the present disclosure include techniques that use both hardware and software, various embodiments of the present disclosure do not exclude software-based access methods.

[0010] Terms used to refer to signals (e.g., signal, information, message, signaling), terms used to refer to resources (e.g., symbol, slot, subframe, radio frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), occasion), terms for operational states (e.g., step, operation, procedure), terms used to refer to data (e.g., packet, user stream, information, bit, symbol, codeword), terms used to refer to channels, terms used to refer to network entities, terms used to refer to components of a device, etc. are exemplified for convenience of explanation. Therefore, the present disclosure is not limited to the terms described hereinafter, and other terms having equivalent technical meanings may be used.

[0011] In the following description, a physical channel and a signal may be used interchangeably with data or a control signal. For example, PDSCH (physical downlink shared channel) is a term that refers to a physical channel through which data is transmitted, but PDSCH may also be used to refer to data. That is, in the present disclosure, the expression "transmit a physical channel" may be interpreted equivalently to the expression "transmit data or a signal through a physical channel".

[0012] Hereinafter, in the present disclosure, higher-layer signaling refers to a signaling method transmitted from a base station to a terminal using a physical layer downlink data channel or from a terminal to a base station using a physical layer uplink data channel. Higher-layer signaling can be understood as RRC (radio resource control) signaling or a MAC control element (hereinafter referred to as "CE").

[0013] Also, in the present disclosure, expressions of exceeding or being less than may be used to determine whether specific conditions are satisfied or fulfilled, but this is only for illustrative purposes and does not exclude descriptions of being greater than or equal to or less than or equal to. The condition described as "greater than or equal to" can be replaced by "exceeding", the condition described as "less than or equal to" can be replaced by "being less than", and the condition described as "greater than or equal to and less than or equal to" can be replaced by "exceeding and being less than". Also, hereinafter, "A" to "B" means at least one of the elements from A (including A) to B (including B). Hereinafter, "C" and / or "D" means at least one of "C" or "D", that is, it includes {"C", "D", "C and D"}.

[0014] In the present disclosure, the signal quality can be, for example, at least one of RSRP (reference signal received power), BRSRP (beam reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), SINR (signal to interference and noise ratio), CINR (carrier to interference and noise ratio), SNR (signal to noise ratio), EVM (error vector magnitude), BER (bit error rate), and BLER (block error rate). Needless to say, in addition to the above-described examples, other terms having an equivalent technical meaning or other metrics indicating the channel quality can be used. Hereinafter, a high signal quality in the present disclosure means a case where the signal quality value related to the signal magnitude is large or the signal quality value related to the error rate is small. It can be meant that a smoother wireless communication environment is ensured as the signal quality is higher. Also, the optimal beam can mean the beam having the highest signal quality among the beams.

[0015] The present disclosure describes various embodiments using terms used in some communication standards (e.g., 3GPP (3rd Generation Partnership Project), ETSI (European Telecommunications Standards Institute)), but this is merely an exemplification for explanation. The various embodiments of the present disclosure can be easily modified and applied in other communication systems.

[0016] FIG. 1 illustrates a wireless communication system.

[0017] Referring to FIG. 1, FIG. 1 is a radio interface of a radio access technology (RAT), and illustrates a terminal 110 and a base station 120 as part of a node that utilizes a radio channel in a wireless communication system using New Radio (NR). Although FIG. 1 illustrates only one base station, the wireless communication system may further include other base stations that are the same as or similar to the base station (e.g., NR gNB) 120.

[0018] The terminal 110 is a device used by a user and communicates with the base station 120 through a radio channel. The link from the base station 120 to the terminal 110 is referred to as the downlink (DL), and the link from the terminal 110 to the base station 120 is referred to as the uplink (UL). Also, although not illustrated in FIG. 1, the terminal 110 and other terminals can communicate with each other through a radio channel. At this time, the link between the terminal 110 and other terminals (device-to-device link, D2D) is referred to as a sidelink, and the sidelink can be used interchangeably with the PC5 interface. In some other embodiments, the terminal 110 can be operated without user involvement. According to one embodiment, the terminal 110 is a device that performs machine type communication (MTC) and may not be carried by a user. Also, according to one embodiment, the terminal 110 can be an NB (narrowband)-IoT (internet of things) device.

[0019] In describing the system and method in this specification, the terminal 110 can be an electronic device used to communicate voice and / or data to the base station 120, and the base station 120 can in turn communicate with a network of devices (e.g., a public switched telephone network (PSTN), the Internet, etc.).

[0020] Further, the terminal 110 may be referred to by terms such as "user equipment (UE)" outside the terminal, "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 having an equivalent technical meaning thereto.

[0021] Examples of the terminal 110 include cellular phones, smartphones, personal digital assistants (PDAs), laptop computers, netbooks, e-readers, wireless modems, and the like. In 3GPP standards, the terminal 110 is typically referred to as a UE. However, since the scope disclosed herein should not be limited to 3GPP standards, the terms "UE" and "terminal" may be used interchangeably herein to mean the more general term "wireless communication device". A UE may also be more generally referred to as a terminal device.

[0022] The base station 120 is a network infrastructure that provides a wireless connection to the terminal 110. The base station 120 has a coverage defined based on the distance it can transmit signals. In 3GPP standards, the base station 120 is generally referred to as "Node B", "evolved Node B (eNodeB, eNB)", "5G node", "gNodeB (next generation NodeB, gNB)", "Home Enhanced or evolved Node B (HeNB)", in addition to "access point (AP)", "wireless point", "transmission / reception point (TRP)" or other terms with equivalent technical meanings.

[0023] Since the scope of the content disclosed in this specification should not be limited to 3GPP standards, the terms "base station", "Node B", "eNB", and "HeNB" can be used interchangeably in this specification to mean the more general term "base station". Also, the term "base station" can be used to denote an access point. An access point can be an electronic device that provides access to a network (e.g., a short-range network (LAN), the Internet, etc.) for wireless communication devices. The term "communication device" can be used to denote all wireless communication devices and / or base stations. An eNB or gNB can also be more generally referred to as a base station device.

[0024] The base station 120 can communicate with an NR Core Network (NR CN) entity 130. For example, the core network entity 130 can include an AMF (Access and Mobility Management Function) responsible for the control plane such as terminal 110 connection and mobility control functions, and a UPF (User Plane Function) responsible for control functions for user data.

[0025] The terminal 110 can perform beamforming with the base station 120. The terminal 110 and the base station 120 can transmit and receive radio signals in a relatively low frequency band (e.g., FR 1 (frequency range 1) of NR). Also, the terminal 110 and the base station 120 can transmit and receive radio signals in a relatively high frequency band (e.g., FR 2 (or FR 2-1, FR 2-2, FR 2-3), FR 3 of NR), millimeter wave (mmWave) band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz). For improving channel gain, the terminal 110 and the base station 120 can perform beamforming. Here, beamforming can include transmit beamforming and receive beamforming. The terminal 110 and the base station 120 can impart directivity to transmitted or received signals. For this purpose, the terminal 110 and the base station 120 can select a serving beam through a beamsearch or beam management procedure. After the serving beam is selected, subsequent communication can be performed through the resources that transmitted the serving beam and resources in a QCL (Quasi Co-Location) relationship.

[0026] If the large-scale characteristics of the channel that transmitted the symbols on the first antenna port can be inferred from the channel that transmitted the symbols on the second antenna port, the first antenna port and the second antenna port can be evaluated as being in a QCL relationship. For example, the large-scale characteristics can include at least one of delay spread, doppler spread, doppler shift, average gain, average delay, and spatial receiver parameter.

[0027] Both the terminal 110 and the base station 120 can perform beamforming, but the embodiments of the present disclosure are not necessarily limited thereto. In some embodiments, the terminal 110 may or may not perform beamforming. Also, the base station 120 may or may not perform beamforming. That is, only one of the terminal 110 and the base station 120 may perform beamforming, or neither the terminal 110 nor the base station 120 may perform beamforming.

[0028] As used in this disclosure, a "beam" refers to the spatial flow of signals over 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 can include at least one of analog beamforming or digital beamforming (e.g., Precoding). The reference signal transmitted based on beamforming can include, for example, DM-RS (demodulation-reference signal), CSI-RS (channel state information-reference signal), SS / PBCH (synchronization signal / physical broadcast channel), and SRS (sounding reference signal). Also, as a configuration for each reference signal, an IE (information element) such as a CSI-RS resource or an SRS-resource can be used, and such a configuration can include information associated with the beam. Information associated with the beam can mean whether the corresponding configuration (e.g., CSI-RS resource) uses the same spatial domain filter as another configuration (e.g., another CSI-RS resource within the same CSI-RS resource set) or a different spatial domain filter, or which reference signal is quasi-co-located (QCL) with it, and if it is QCL, what type (e.g., QCL type A, B, C, D) it is.

[0029] Hereinafter, for the purpose of explaining the embodiments, the terminal may be referred to as UE110, and the base station may be referred to as gNB120.

[0030] Figures 2a and 2b illustrate examples of non-terrestrial networks (NTNs). In Figure 2a, an example of an NTN that utilizes a transparent satellite is illustrated. In Figure 2b, an example of an NTN that utilizes a regenerative satellite is illustrated. NTN means an NG-RAN that provides non-terrestrial NR access to a UE (e.g., UE110) through an NTN payload mounted on an airborne or space-borne base NTN vehicle and an NTN gateway. The NG-RAN can include one or more gNBs (e.g., gNB120).

[0031] Referring to Figure 2a, NTN 200 shows the network environment by the transparent satellite. NTN 200 is a gNB 120 and can include an NTN payload 221 and an NTN gateway 223. The NTN payload 221 is a network node mounted on a phase or HAPS (high altitude platform station) that provides a connection function between a service link (described later) and a feeder link (described later). The NTN gateway 223 is an earth station located on the earth's surface that provides a connection to the NTN payload 221 using the feeder link. The NTN gateway 223 is a TNL (transport network layer) node. NTN 200 can provide non-terrestrial NR access to UE 110. NTN 200 can provide non-terrestrial NR access to UE 110 through the NTN payload 221 and the NTN gateway 223. The link between the NTN payload 221 and UE 110 can be referred to as a service link. The link between the NTN gateway 223 and the NTN payload 221 can be referred to as a feeder link. The feeder link can correspond to a wireless link.

[0032] The NTN payload 221 can receive radio protocol data from the UE 110 through the service link. The NTN payload 221 can transparently transmit the radio protocol data to the NTN gateway 223 through the feeder link. Therefore, the NTN payload 221 and the NTN gateway 223 may appear as one gNB 120 from the perspective of the UE 110. The NTN payload 221 and the NTN gateway 223 can communicate with the UE 110 through the Uu interface, which is a common radio protocol. That is, the NTN payload 221 and the NTN gateway 223 can perform radio protocol communication with the UE 110 as if they were one gNB 120. The NTN gateway 223 can communicate with the core network entity 235 (AMF or UPF) through the NG interface.

[0033] According to one embodiment, the NTN payload 221 and the NTN gateway 223 can utilize the radio protocol stack in the control plane of FIG. 3a, which will be described later. Also, according to one embodiment, the NTN payload 221 and the NTN gateway 223 can utilize the radio protocol stack in the user plane of FIG. 3b.

[0034] In FIG. 2a, one NTN payload 221 and one NTN gateway 223 included in the gNB 120 are described, but the embodiments of the present disclosure are not limited thereto. For example, the gNB can include multiple NTN payloads. Also, for example, the NTN payload can be provided by multiple gNBs. That is, the implementation scenario illustrated in FIG. 2a is an example and does not limit the embodiments of the present disclosure.

[0035] Referring to FIG. 2b, NTN250 shows the network environment by the regenerative satellite. NTN250 can include a satellite 260 operating as a gNB120. The satellite 260 represents a space-borne vehicle equipped with a regenerative payload communication transmitter located in a low-earth orbit (LEO), a medium-earth orbit (MEO), or a geostationary earth orbit (GEO). The satellite 260 can be referred to as a regenerative payload or a regenerative satellite. The satellite 260 represents a vehicle configured to convert and amplify an uplink RF signal before transmitting it to the downlink, and the conversion of the signal can mean digital processing that can include demodulation, decoding, re-encoding, remodulation, and / or filtering. NTN250 can include an NTN gateway 265, which is an entity located on the ground and connected to the satellite 260. The NTN gateway 265 is an earth station located on the earth's surface that provides a connection to the satellite 260 using the feeder link. NTN250 can provide non-terrestrial NR access to the UE110. NTN250 can provide non-terrestrial NR access to the UE110 through the satellite 260 and the NTN gateway 265.

[0036] Satellite 260 can be configured to regenerate signals received from the Earth. A Uu interface can be defined between satellite 260 and terminal 110. An SRI (satellite radio interface) on the feeder link can be defined between satellite 260 and NTN gateway 265. Although not shown in FIG. 2b, satellite 260 can provide inter-satellite ISLs (inter-satellite links). The ISL may be a transmission link between satellites, and the ISL may be a radio interface defined by 3GPP (e.g., XN interface) or an optical interface not defined by 3GPP. Satellite 260 can communicate with core network entity 235 (AMF or UPF) through the NG interface based on NTN gateway 265. According to one embodiment, satellite 260 can utilize the radio protocol stack in the control plane of FIG. 3a described below. Also, according to one embodiment, satellite 260 can utilize the radio protocol stack in the user plane of FIG. 3b.

[0037] Although the satellite 260 operating as the gNB 120 was described in FIG. 2b, embodiments of the present disclosure are not limited thereto. The gNB 120 according to an embodiment may be implemented in a distributed deployment using a centralized unit (CU) configured to perform functions of upper layers (e.g., packet data convergence protocol (PDCP), radio resource control (RRC)) of an access network and a distributed unit (DU) configured to perform functions of lower layers. The interface between the CU and the DU (distributed unit) may be referred to as the F1 interface. The CU (centralized unit) is connected to one or more DUs and may be responsible for functions of upper layers than the DUs. For example, the CU may be responsible for functions of the RRC (radio resource control) and PDCP (packet data convergence protocol) layers, and the DU and the radio unit (RU) may be responsible for functions of lower layers. The DU may be responsible for functions of the radio link control (RLC), media access control (MAC), and physical (PHY) layers. In such a distributed deployment, the satellite 260 may be used as a CU or a DU constituting the gNB 120.

[0038] FIG. 3a illustrates an example of a control plane (C-plane). Hereinafter, at least a part of the description of the gNB 120 may be understood to apply to the satellite 260.

[0039] Referring to FIG. 3a, in the C-plane, the UE 110 and the AMF 235 can perform non-access stratum (NAS) signaling. In the C-plane, the UE 110 and the gNB 120 can perform communication according to protocols specified in each of the RRC layer, PDCP layer, RLC layer, MAC layer, and PHY layer.

[0040] In NTN access, the main functions of the RRC layer can include at least some of the following functions.

[0041] - Broadcast of AS (Access Stratum) and NAS related system information - Paging initiated by 5GC (5G Core) or NG-RAN (Next Generation-Radio Access network) - Setup, maintenance, and release of the RRC connection between the UE and the NG-RAN, more specifically including control of RLC, MAC, and PHY: - Addition, modification, and removal of Carrier Aggregation - Addition, modification, and removal of dual connectivity between NR or between E-UTRA and NR.

[0042] - Security functions including Key Management; - Setup, configuration, maintenance, and release of SRB (Signaling Radio Bearer) and DRB (Data Radio Bearer) - Mobility functions including: - Handover and context transfer; - UE cell selection and reselection and cell selection and reselection control; - Inter-RAT mobility.

[0043] - QoS (quality of service) management functions; - UE measurement reporting and reporting control; - Detection and recovery of radio link failure - Message transmission from / to the UE to / from the NAS.

[0044] In NTN access, the main functions of the PDCP layer can include at least some of the following functions.

[0045] - Header compression and decompression: ROHC only - Transfer of user data - In-sequence delivery of upper layer PDUs - Out-of-sequence delivery of upper layer PDUs - PDCP PDU reordering for reception - Duplicate detection of lower layer SDUs - Retransmission of PDCP SDUs - Ciphering and deciphering - Timer-based SDU discard in uplink. In NTN access, the main functions of the RLC layer can include at least some of the following functions.

[0046] - Transfer of upper layer PDUs - In-sequence delivery of upper layer PDUs - Out-of-sequence delivery of upper layer PDUs - Error Correction through ARQ - Concatenation, segmentation and reassembly of RLC SDUs - Re-segmentation of RLC data PDUs - Reordering of RLC data PDUs - Duplicate detection - Protocol error detection - RLC SDU discard - RLC re - establishment In NTN access, the MAC layer can be connected to multiple RLC layer devices configured in one terminal, and the main functions of the MAC can include at least some of the following functions.

[0047] - Mapping between logical channels and transport channels - Multiplexing / demultiplexing of MAC SDUs - Scheduling information reporting - Error correction through HARQ - Priority handling between logical channels of one UE - Priority handling between UEs by means of dynamic scheduling - MBMS service identification - Transport format selection - Padding In NTN access, the physical layer can perform operations such as channel coding and modulating the upper layer data, creating it into OFDM symbols and transmitting them over the radio channel, or demodulating the OFDM symbols received through the radio channel, performing channel decoding, and transmitting them to the upper layer.

[0048] Figure 3b illustrates an example of the user plane (U-plane). Hereinafter, at least a part of the description of gNB120 can be understood to apply to satellite 260.

[0049] Referring to Figure 3b, in the U-plane, UE110 and gNB120 can perform communication according to the protocols specified 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 excluding the SDAP layer, the description of Figure 3a can be referred to.

[0050] In NTN access, the SDAP layer can provide QoS flows of 5GC. A single protocol entity of SDAP can be configured for each individual PDU session, and the functions of the SDAP layer can include at least some of the following functions.

[0051] - Mapping between QoS flow and data radio bearer; - QoS flow ID (QFI) indication for both DL and UL packets. Figure 4 illustrates an example of the resource structure in the time-frequency domain supported by a wireless communication system to which the embodiments proposed in this specification can be applied. Figure 4 exemplifies the basic structure of the time-frequency domain, which is a wireless resource area where data or control channels are transmitted in the downlink or uplink in a 5G NR system to which this embodiment can be applied.

[0052] Referring to Figure 4, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol, N symbA number of OFDM symbols 402 gather to form one slot 406. Referring to FIG. 4, in a wireless communication system to which the present invention is applied, one radio frame 414 can be defined as having a length of 10 ms and being composed of 10 subframes each having the same length of 1 ms. And one radio frame 414 can be divided into two half-frames each having a length of 5 ms, and each half-frame includes 5 subframes. In FIG. 4, the slot 406 is composed of 14 OFDM symbols, but the length of the slot can vary depending on the subcarrier spacing. For example, in the case of numerologies having a 15 kHz subcarrier spacing, the slot has a length of 1 ms and is configured to have the same length as the subframe. In contrast, in the case of numerologies having a 30 kHz subcarrier spacing, the slot is composed of 14 OFDM symbols, but has a length of 0.5 ms and two slots can be included in one subframe.

[0053] That is, the subframe and the frame are defined as having fixed time lengths, and the slot is defined by the number of symbols and the time length can vary depending on the subcarrier spacing. Referring to FIG. 4 again, in a wireless communication system where the invention proposed in this specification can be applied, the radio resources supported are composed of symbols of a plurality of time resources and sub-carriers of a plurality of frequency resources, and each time resource and frequency resource can be represented by a two-dimensional resource grid. In FIG. 4, one of the smallest physical resources composed of one subcarrier and one symbol in the resource grid is called a resource element (RE) 412.

[0054] In the 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 composed of NBW subcarriers 404.

[0055] In the time-frequency domain, the basic unit of resources is a resource element (hereinafter referred to as "RE") 412, which can be indicated by an OFDM symbol index and a subcarrier index. A resource block 408 can include a plurality of resource elements 412. In the 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")) is N symb consecutive OFDM symbols in the time domain and N SC RB consecutive subcarriers in the frequency domain. In the NR system, a resource block (RB) 408 can be defined by N SC RB consecutive subcarriers 410 in the frequency domain. One RB 408 includes N SC RB resource elements 412 in the frequency axis.

[0056] Generally, the minimum transmission unit of data is an RB, and the number N SC RB of subcarriers is 12. The frequency domain can include a common resource block (CRB). A physical resource block (PRB) can be defined in a bandwidth part (BWP) on the frequency domain. The CRB and PRB numbers can be determined by the subcarrier spacing. The data rate can increase in proportion to the number of RBs scheduled for the terminal.

[0057] In the NR system, in the case of an FDD (frequency division duplex) system that operates by separating the downlink and uplink by frequency, the downlink transmission bandwidth and the uplink transmission bandwidth can be different from each other. The channel bandwidth indicates the RF (radio frequency) bandwidth corresponding to the system transmission bandwidth. [Table 1] shows a part of the correspondence between the system transmission bandwidth, subcarrier spacing (SCS), and channel bandwidth defined in the NR system in a frequency band lower than the upper limit (e.g., 7.125) GHz defined in the standard (e.g., FR (frequency range) 1 (410 MHz to 7125 MHz)). And [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 higher than the lower limit (e.g., 24.25 GHz) defined in the standard (e.g., FR2 (24250 MHz - 52600 MHz) or FR2-2 (52600 MHz to 71000 MHz)). For example, an NR system with a 100 MHz channel bandwidth and a 30 kHz subcarrier spacing has a transmission bandwidth composed of 273 RBs. In [Table 1] and [Table 2], N / A can be a bandwidth-subcarrier combination not supported in the NR system.

[0058]

Table 1

[0059]

Table 2

[0060] Referring to FIG. 5, the satellite 260 can operate as a gNB120. The gNB120 can communicate with the terminal 110 or communicate with the core network entity 130. In FIG. 5, the UPF550 is illustrated as the core network entity 130. The NR Uu interface 502 can be used between the satellite 260 and the terminal 110. According to one embodiment, at least one radio bearer 520 can be generated between the satellite 260 and the terminal 110. For example, the radio bearer 520 can include a data radio bearer (DRB). For example, the radio bearer 520 can include a signaling radio bearer (SRB). The NG interface 504 can be used between the satellite 260 and the core network entity (e.g., AMF, UPF). For example, the N3 interface can be used between the satellite 260 and the UPF. For example, the N2 interface can be used between the satellite 260 and the AMF. According to one embodiment, a traffic tunnel can be generated between the satellite 260 and the core network entity 130. For example, the NG-U tunnel 530 can be generated between the satellite 260 and the UPF550.

[0061] A PDU (packet data unit) session 540 can be generated between the UE110 and the core network entity 130 (e.g., UPF550). The PDU session 540 can be used to provide an end-to-end user plane connection between the terminal 110 and the data network through the UPF550. The PDU session 540 can support one or more QoS (quality of service) flows. For example, the PDU session 540 can support the first QoS flow 511 and the second QoS flow 512. In the user plane, the radio bearer 520 can be mapped to the QoS flow (e.g., the first QoS flow 511, the second QoS flow 512). According to one embodiment, the satellite 260 can perform the mapping between the DRB and the QoS flow as the gNB120.

[0062] Although not shown in FIG. 5, O&M (operation and maintenance) can be utilized to provide a wireless access network through satellite 260. O&M can provide one or more parameters related to NTN500 to gNB120 (e.g., satellite 260). For example, O&M (operation and maintenance) 510 can provide at least the following NTN-related parameters to gNB120 for operation.

[0063] a) Earth fixed beams: For each beam provided by a given NTN payload: - Cell identifiers (NG and Uu) mapped to the beam - Reference location of the cell (e.g., center and extent of the cell).

[0064] b) Quasi earth fixed beams: For each beam provided by a given NTN payload: - Cell identifiers (NG and Uu) and time window mapped to the beam; - Reference location of the cell / beam (e.g., center and extent of the cell) - Time window for continuous switch-over (feeder link, service link) - Identifiers and time windows of all satellites and NTN gateways providing the service. c) Earth moving beams: For each beam provided by a given NTN payload: - Uu cell identifier mapped to the beam and mapping information for a fixed geographical area reported to NG, information on the movement of the beam's footprint on the earth; - Elevation with respect to the NTN payload; - Continuous service schedule for the NTN-gateway / gNB; - Continuous switch-over schedule (feeder link, service link).

[0065] FIG. 6a illustrates an example of a control plane of a regenerative satellite (e.g., satellite 260).

[0066] Referring to FIG. 6a, UE 610 can support protocols of the PHY layer, MAC layer, RLC layer, PDCP layer, and RRC layer. Satellite 620 is a gNB and can support protocols of the PHY layer, MAC layer, RLC layer, PDCP layer, and RRC layer. For satellite 620, the description of satellite 260 can be referred to. The description of the protocol of each layer can refer to the description of FIG. 3a. The interface between UE 610 and satellite 620 can be the Uu interface.

[0067] Satellite 620 is a gNB on board or a part of the gNB that can perform NG-RAN protocol functions. Satellite 620 can communicate (e.g., IP communication) with the ground-based NTN gateway 630 through SRI. Satellite 620 can be connected to 5GC through NTN gateway 630. As network entities for the 5GC, AMF 640 (e.g., AMF 235) and SMF 650 are exemplified. Satellite 620 can support protocols of the NG-AP layer, SCTP (stream control transmission protocol) layer, and IP layer for communication with 5GC. The NG-AP layer can be utilized over SCTP between the 5GC entity AMF 640 and Satellite 620 through the NTN gateway. NAS signaling between UE 610 and AMF 640 can be performed through Satellite 620 and NTN gateway 630. The NAS signaling can include a NAS-MM (mobility management) interface for AMF 640. The NAS signaling can include a NAS-SM relay and / or NAS-SM (session management) for SMF 650. The NAS signaling can be transmitted through the NTN gateway 630 between the 5GC entity AMF 640 and Satellite 620 through the protocol of the NG-AP layer.

[0068] In FIG. 6a, an example where the satellite operates as a complete gNB is described, but the embodiments of the present disclosure are not limited thereto. As a non-limiting example, the satellite can operate as a gNB-DU by functional separation. Accordingly, the satellite may be configured to support protocols of the RLC layer, MAC layer, and PHY layer.

[0069] FIG. 6b illustrates an example of the user plane of a regenerative satellite (e.g., satellite 260).

[0070] Referring to FIG. 6b, UE 610 can support the protocols of the PHY layer, MAC layer, RLC layer, PDCP layer, and SDAP layer. Satellite 620 is a gNB and can support the protocols of the PHY layer, MAC layer, RLC layer, PDCP layer, and SDAP layer. The description of the protocols for each layer can refer to the description in FIG. 3b. The interface between UE 610 and satellite 620 can be the Uu interface.

[0071] Satellite 620 is a gNB mounted on board and can perform the NG-RAN protocol functions. Satellite 620 can communicate (e.g., IP communication) with the ground-based NTN gateway 630 through SRI. Satellite 620 can connect to the 5GC through NTN gateway 630. As a network entity for the 5GC, UPF 680 is exemplified. Satellite 620 can support the protocols of the GTP-U (GPRS (General Packet Radio Service) tunneling protocol-user plane) layer, UDP (user datagram protocol) layer, and IP layer for communication with the 5GC. A PDU session between UE 610 and UPF 680 (e.g., PDU session 540 in FIG. 5) can be generated. The protocol stack of SRI can be used to transmit the UE user plane between the satellite and the NTN-gateway. Signals on the PDU session can be transmitted through the GTP-U tunnel between UPF 680, which is the 5GC, and satellite 620 through NTN gateway 630.

[0072] Although an example where the satellite operates as a complete gNB is described in FIG. 6b, the embodiments of the present disclosure are not limited thereto. As a non-limiting example, the satellite can operate as a gNB-DU by functional separation. Accordingly, the satellite may be configured to support the protocols of the RLC layer, MAC layer, and PHY layer.

[0073] The signal transmitted from the base station to the terminal is referred to as a downlink signal, and the signal transmitted from the terminal to the base station can be referred to as an uplink signal. In the LTE standard, the waveform applied to the downlink signal is OFDM (orthogonal frequency division multiplexing), while the waveform applied to the uplink signal is DFT-S (discrete fourier transform-spreading) OFDM. In order to solve the problem of high PAPR (peak-to-average power ratio) in OFDM, when the terminal with power constraints transmits the uplink signal, it modulates the signal using the DFT-S OFDM method. In the 5G NR standard, for the downlink signal, the existing OFDM method (referred to as CP (cyclic prefix) OFDM for example) is applied, while for the uplink signal, the OFDM method or the DFT-S OFDM method is adaptively applied. That is, when transmitting the uplink signal according to the situation of the terminal, the modulation method can be changed.

[0074] Such an assumption is because the base station (network) transmitting the downlink signal has almost no constraints in terms of power consumption, while the terminal transmitting the uplink signal has limitations in terms of power consumption. However, with the development of technology, a non-terrestrial network, that is, satellite communication, is introduced to reduce the out-of-service area and increase the coverage. As a result, instead of the existing network entities arranged on the ground, the satellite located in the air transmits the downlink signal. Since the satellite not only moves in its orbit periodically but is also located non-terrestrially, power problems may occur. Therefore, in the embodiments of the present disclosure, techniques for power saving in satellites are described.

[0075] DL DFT-S OFDM (Transform precoding Enabled) FIG. 7 illustrates an example of transform precoding. The application of the transform precoding indicates that the modulation method of the waveform is the DFT-S (discrete fourier transform-spreading) method.

[0076] Referring to FIG. 7, in a non-terrestrial network, the downlink transmission waveform can utilize transform precoding 701. A satellite (e.g., satellite 620) can modulate the downlink signal through transform precoding 701, subcarrier mapping 703, IFFT (Inverse Fast Fourier Transform) 705, and CP insertion 707. Transform precoding 701 performs a discrete Fourier transform (DFT)-based spreading process. That is, transform precoding 701 indicates that DFT spreading is performed using the CP-OFDM (orthogonal frequency division multiplexing with cyclic prefix) technique. The downlink transmission waveform can be in the CP-OFDM mode or the DFT-S OFDM mode depending on the activation or deactivation of DFT spreading.

[0077] For example, when transform precoding 701 is activated for downlink data (e.g., PDSCH), the following mathematical formula can be referred to.

Equation

[0078] M SC PDSCH represents the product of the number of RBs scheduled for PDSCH and the number of subcarriers (N SC RB (=12)), and according to Equation 1, the symbol can be modulated.

[0079] FIG. 8 illustrates signaling for downlink transmission using transform precoding. The same reference numbers may represent the application of the same description.

[0080] Referring to FIG. 8, in operation 801, the UE 610 can transmit capability information to the satellite 620. According to one embodiment, the capability information can indicate whether the UE 610 can receive downlink transmission to which transform precoding is applied. For example, a change in the waveform of the downlink signal can cause a change in the hardware of the entity (e.g., the UE 610) that processes the downlink signal. In the network (e.g., the satellite 620), in order to determine whether to receive the downlink transmission, the satellite 620 can preferentially receive the capability information from the UE 610.

[0081] In operation 803, the satellite 620 can transmit RRC configuration information to the UE 610. The RRC configuration information can include configuration information related to downlink transmission. For example, the RRC configuration information can include configuration information for a control signal (e.g., PDCCH). The configuration information for the control signal can indicate whether to activate transform precoding during the generation of the control signal. If the transform precoding is activated, the control signal can be generated by the DFT-S OFDM method. For example, the RRC configuration information can include configuration information for data (e.g., PDSCH). The configuration information for the data can indicate whether to activate transform precoding. If the transform precoding is activated, the data can be generated by the DFT-S OFDM method.

[0082] According to the embodiment, the RRC configuration information can include various information in addition to simply indicating the presence or absence of activation of transform precoding. According to one embodiment, the RRC configuration information can include information regarding the MCS table when transform precoding is activated. The MCS table can be used to indicate the modulation scheme of the data transmitted between the UE610 and the satellite 620. The UE610 can utilize different MCS tables depending on whether the downlink transmission is in the DFT-S OFDM mode or the CP-OFDM mode to determine the modulation scheme of the indicated MCS index. For example, the RRC configuration information can include the following information.

[0083]

Table 3

[0084]

Table 4

[0085]

Table 5-01

[0086]

Table 5-02

[0087]

Table 6

[0088] In operation 805, satellite 620 can perform downlink transmission.

[0089] Satellite 620 can generate a downlink signal according to the RRC configuration information of operation 803 as instructed. For example, when the RRC configuration information instructs the DFT-S OFDM scheme (e.g., activation of transform precoding 701), satellite 620 can generate a downlink signal through a series of procedures illustrated in FIG. 7. For example, when the RRC configuration information instructs the CP-OFDM scheme (e.g., deactivation of transform precoding 701), satellite 620 can generate a downlink signal through subcarrier mapping 703, IFFT (Inverse Fast Fourier Transform) 705, and CP insertion 707, excluding transform precoding 701, among the series of procedures illustrated in FIG. 7. The downlink signal can be transmitted on PDCCH or PDSCH and can include DMRS and / or PTRS.

[0090] In FIG. 8, it is indicated whether the downlink transmission of satellite 620 uses the DFT-S OFDM scheme or the CP-OFDM scheme through the RRC configuration information, but the embodiments of the present disclosure are not limited thereto. As a non-limiting example, satellite 620 may instruct the DFT-S OFDM scheme (e.g., activation of transform precoding 701) through MAC CE or DCI. Also, in FIG. 8, an example is described in which after UE 610 transmits capability information to satellite 620, satellite 620 transmits an RRC configuration message to UE 610, but the embodiments of the present disclosure are not limited thereto. As a non-limiting example, the operation of transmitting the capability information in operation 801 can be performed independently of the configuration operation of satellite 620. For example, operation 801 may be omitted.

[0091] FIG. 9a illustrates an example of signaling through the NG interface by NTN. The same reference numbers may represent the application of the same description. In downlink transmission, whether to use the DFT-S OFDM scheme or the CP-OFDM scheme may depend on the state of the satellite (e.g., satellite 620). For example, if the power state of satellite 620 is not normal or it is predicted that the PAPR problem will increase due to a large number of UEs connected to satellite 620, satellite 620 can change the waveform setting for downlink transmission from the CP-OFDM scheme to the DFT-S OFDM scheme. Such a decision may be made autonomously by satellite 620 or may be made by a separate network entity (e.g., AMF 640) that manages satellite 620.

[0092] Referring to FIG. 9a, in operation 901, AMF 640 can transmit an indication message for waveform setting of the downlink signal to satellite 620. The indication message can include information related to the downlink signal on the cell provided by satellite 620. Satellite 620 can transmit the downlink signal to the terminal (e.g., UE 610) according to the indication message.

[0093] According to one embodiment, the indication message can indicate the presence or absence of activation of transform precoding (e.g., transform precoding 701). For example, the presence or absence of activation of the transform precoding can be determined cell-specifically. The indication message can include a cell identifier (e.g., physical cell ID or CGI (cell global identity)). For example, the presence or absence of activation of the transform precoding can be determined terminal-specifically. The indication message can include a UE ID (e.g., GUAMI (global unique AMF identifier)) specified by the NG interface. For example, the indication message may include a "DL-transformPrecodingEnabled" IE.

[0094] According to one embodiment, the indication message can indicate the time when transform precoding (e.g., transform precoding 701) is activated. When transform precoding is activated, the spectrum efficiency becomes low, and the additional operation of DFT spreading may increase the complexity of signal processing. Therefore, when the activation of the transform precoding is indicated in the indication message, the indication message can include information (e.g., a timer) regarding the time for which the activation is maintained. The timer can start from a specific time point (e.g., the time when downlink transmission starts or the time when the indication message is received). When the timer expires, the satellite 620 can change the waveform setting from DFT-S OFDM to CP-OFDM. For example, the indication message may include a "DL-transformPrecodingEnabled Timer" IE.

[0095] According to one embodiment, the indication message can include information regarding the geographical area where the transform precoding is utilized. The satellite 620 can be configured to move along an orbit around a celestial body. The DFT-S OFDM scheme can provide a wider cell coverage and higher power efficiency compared to the CP-OFDM scheme. Therefore, on the side of the satellite 620 orbiting around a celestial body (e.g., the Earth), in an area where out-of-coverage regions are relatively predicted to be numerous or in an area where the number of other satellites providing access networks is relatively small, expanding the coverage of the satellite 620 may be advantageous for continuous service provision. For example, the indication message can include information regarding a tracking area (e.g., a TAI (tracking area identity) list). For example, the indication message may include a "TAI list for TransformPrecoding" IE.

[0096] The indication message can be newly defined or used as a message defined on an existing NG interface. According to one embodiment, the indication message can be the "INITIAL CONTEXT SETUP REQUEST" message. The indication message can include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information about the geographical area where the transform precoding is used (e.g., TAI list), and information about the time when the transform precoding is activated (e.g., timer). Whether the transform precoding is activated can be indicated on a per-UE basis. For example, the indication message can further include, in addition to the aforementioned transform precoding-related information, AMF UE NGAP ID, RAN UE NGAP ID, GUAMI, PDU session ID, S-NSSAI (Single-Network Slice Selection Assistance Information), etc.

[0097] According to one embodiment, the indication message can be the "UE Context Modification Request" message. The indication message can include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information about the geographical area where the transform precoding is used (e.g., TAI list), and information about the time when the transform precoding is activated (e.g., timer). Whether the transform precoding is activated can be indicated on a per-UE basis. For example, the indication message can further include, in addition to the aforementioned transform precoding-related information, AMF UE NGAP ID, RAN UE NGAP ID, PDU session ID, S-NSSAI, etc.

[0098] According to one embodiment, the indication message may be a "PDU SESSION RESOURCE SETUP REQUEST" message. The indication message can include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The activation status of the transform precoding can be indicated on a per-UE basis. For example, the indication message can further include an AMF UE NGAP ID, a RAN UE NGAP ID, a GUAMI, a PDU session ID, an S-NSSAI, etc. in addition to the aforementioned transform precoding-related information.

[0099] According to one embodiment, the indication message may be a "PDU SESSION RESOURCE MODIFY REQUEST" message. The indication message can include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The activation status of the transform precoding can be indicated on a per-UE basis. For example, the indication message can further include an AMF UE NGAP ID, a RAN UE NGAP ID, a GUAMI, a PDU session ID, an S-NSSAI, etc. in addition to the aforementioned transform precoding-related information.

[0100] According to one embodiment, the indication message may be a "WRITE-REPLACE WARNING REQUEST" message. A scenario where public disaster characters are provided via a satellite may be considered. The indication message may include at least one of information indicating the activation or deactivation of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The activation or deactivation of the transform precoding may be indicated on a per-UE basis. For example, the indication message may further include a message identifier, a serial number, a repetition period, a broadcast count, a warning type, and / or message content.

[0101] FIG. 9b illustrates an example of signaling through the F1 interface in NTN. The same reference numerals may represent the application of the same description.

[0102] Referring to FIG. 9b, in operation 903, the gNB-CU 920 can transmit an indication message to the gNB-DU 910 corresponding to the satellite. The indication message may include information related to the downlink signal on the cell provided by the satellite 620. The satellite 620 can transmit the downlink signal to the terminal (e.g., UE 610) based on the indication message.

[0103] According to one embodiment, the indication message can indicate the presence or absence of activation of transform precoding (e.g., transform precoding 701). For example, the presence or absence of activation of the transform precoding can be determined cell - specifically. The indication message can include a cell identifier (e.g., physical cell ID or CGI (cell global identity)). For example, the presence or absence of activation of the transform precoding can be determined terminal - specifically. The indication message can include a UE ID (e.g., GUAMI (global unique AMF identifier)) specified in the NG interface. For example, the indication message can include a "DL - transformPrecodingEnabled" IE.

[0104] According to one embodiment, the indication message can indicate the time when transform precoding (e.g., transform precoding 701) is activated. When transform precoding is activated, the spectrum efficiency becomes low, and due to the additional operation of DFT spreading, the signal processing complexity can increase. Therefore, when the activation of the transform precoding is indicated in the indication message, the indication message can include information (e.g., a timer) regarding the time for which the activation is maintained. The timer can start from a specific time point (e.g., the time when downlink transmission starts or the time when the indication message is received). When the timer expires, the satellite 620 can change the waveform setting from DFT - S OFDM to CP - OFDM. For example, the indication message can include a "DL - transformPrecodingEnabled Timer" IE.

[0105] According to one embodiment, the indication message may include information about the geographical area where the transform precoding is used. The satellite 620 may be configured to move along an orbit around a celestial body. The DFT-S OFDM scheme can provide a wider cell coverage and higher power efficiency compared to the CP-OFDM scheme. Therefore, on the side of the satellite 620 orbiting around a celestial body (e.g., the Earth), in an area where there are relatively many out-of-coverage regions predicted or an area where the number of other satellites providing access networks is relatively small, expanding the coverage of the satellite 620 may be advantageous for continuous service provision. For example, the indication message may include information about a tracking area (e.g., a TAI (tracking area identity) list). For example, the indication message may include an "IE" of "TAI list for TransformPrecoding".

[0106] The indication message may be used as a newly defined message or a message defined on an existing NG interface.

[0107] According to one embodiment, the indication message may be a "GNB-DU CONFIGURATION UPDATE" message. The indication message may include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information about the geographical area where the transform precoding is used (e.g., a TAI list), and information about the time when the transform precoding is activated (e.g., a timer). The activation status of the transform precoding may be indicated on a per-cell basis. For example, the indication message may include information about a serving cell (e.g., serving cell information, system information of the gNB-DU). The indication message may include information about an additional serving cell or a modified serving cell. The indication message may include DU identification information (e.g., gNB-DU ID).

[0108] According to one embodiment, the indication message may be a "NETWORK ACCESS RATE REDUCTION" message. The indication message may include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The indication message may further include information for setting parameters for unified access class (uac) barring (e.g., PLMN (public land mobile network) identifier, UAC type, access category, access identifier).

[0109] According to one embodiment, the indication message may be a "RESOURCE STATUS REQUEST" message. The indication message may include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The activation status of the transform precoding may be indicated on a cell-by-cell basis. The indication message may include cell information, slice information, and / or beam information (e.g., SSB (SS / PBCH block) index).

[0110] According to one embodiment, the indication message may be a "UE CONTEXT SETUP REQUEST" message. The indication message may include at least one of information indicating the presence or absence of activation of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The presence or absence of transform precoding activation may be indicated on a per-UE basis. The above indication message may include information such as gBNB-CUUE F1AP ID, gNB-DUUE F1AP ID, SpCell ID (e.g., PCell of MCG (master cell group) and PCell of SCG (secondary cell group)), SCell (secondary cell) index, DRX (discontinuous reception) cycle, SRB (signaling radio bearer) information, and / or DRB (data radio bearer) information.

[0111] According to one embodiment, the indication message may be a "UE CONTEXT MODIFICATION REQUEST" message. The indication message can include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The activation status of the transform precoding can be indicated on a per-UE basis. The above indication message can include gBNB-CUUE F1AP ID, gNB-DUUE F1AP ID, SpCell ID (e.g., PCell of MCG (master cell group) and PCell of SCG (secondary cell group)), DRX (discontinuous reception) cycle, SCell (secondary cell) index, and / or information regarding the RRC container. The RRC container can directly include the message containing the RRC configuration information of FIG. 8.

[0112] According to one embodiment, the indication message may be a "DL RRC MESSAGE TRANSFER" message. The indication message can include at least one of information indicating the activation status of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The activation status of the transform precoding can be indicated on a per-UE basis. The above indication message can include gBNB-CUUE F1AP ID, gNB-DUUE F1AP ID, and / or the RRC container. The RRC container can directly include the message containing the RRC configuration information of FIG. 8.

[0113] According to one embodiment, the indication message may be a "WRITE-REPLACE WARNING REQUEST" message. The indication message can include at least one of information indicating the activation or deactivation of transform precoding (e.g., transform precoding 701), information regarding the geographical area where the transform precoding is used (e.g., TAI list), and information regarding the time when the transform precoding is activated (e.g., timer). The activation or deactivation of the transform precoding can be indicated on a cell-by-cell basis. The above indication message can include PWS (public warning system) information (e.g., SIB (system information block) 6, 7, 8), repetition period, information regarding the number of broadcasts, and cell information (e.g., CGI).

[0114] 2. Satellite ON / OFF Through FIGS. 7, 8, 9a, and 9b, examples of changing the waveform setting from the CP-OFDM scheme to the DFT-S OFDM scheme or from the DFT-S OFDM scheme to the CP-OFDM scheme according to the state of the satellite 620 were described. Downlink transmission using the DFT-S OFDM scheme is advantageous in terms of the power efficiency of the satellite. On the other hand, power saving of the satellite may be achieved by deactivating a satellite or a cell provided by the satellite that is determined to be unnecessary. Hereinafter, through FIGS. 10 to 13, techniques for increasing the power efficiency in a non-terrestrial network through the deactivation or activation of a satellite or a cell provided by the satellite will be described.

[0115] FIG. 10 illustrates an example of a selection procedure for a deactivated satellite. The same reference numerals may represent the application of the same description.

[0116] In operation 1001, the AMF 640 can identify the satellite corresponding to the sector. Here, the sector may indicate a geographical area. The satellite can provide services for various geographical areas on the celestial body. For example, the geographical area of the region served by the cell in 3GPP may correspond to the TA (tracking area) for managing the mobility of the UE 610. The TAI (tracking area identity) can be specified by the MCC (mobile country code), MNC (mobile network code), and TAC (tracking area code). For example, the said geographical area may correspond to the TAC (tracking area code). The AMF 640 can identify the satellite related to the said geographical area. As another example, the said geographical area may be a space area defined by the orbit of the satellite. The said space area may be in the form of a sphere surrounding the outside of the celestial body and is a unit that physically divides the position of the satellite. The higher the orbit of the satellite is from the center of the celestial body, the larger the spherical form surrounding the outside can be. The higher the orbit, the more the number of the said space areas may increase or the area of the unit space area may increase. The AMF 640 can identify the satellite related to the said space area. As yet another example, the said geographical area may be an area arbitrarily defined by the operator managing the satellite. The operator can manage the said geographical area through the area type, the list of serviceable satellites, and / or the set of beams of the said serviceable satellites. The said geographical area can be specified by the type, the list of satellite(s), and / or the list of beam(s). The AMF 640 can identify the satellite(s) included in the list of the said satellite(s).

[0117] In operation 1003, the AMF 640 can identify a satellite based on prediction information. The AMF 640 can identify a satellite based on prediction information among the satellites corresponding to the sector. The satellite indicates a deactivated satellite. The prediction information indicates information related to a satellite predicted at a specific future time point. According to one embodiment, the prediction information can indicate information about an area where a satellite is predicted to be located at a specific time when considering the orbit of the satellite. The time can indicate a season, a month, a day, a year, or a specific time period of a day. For example, the area can be divided by a TA (tracking area) defined by 3GPP. For example, the area can be divided by a geographical code (e.g., postal code). For example, the information about the area can indicate the type of the area. The type of the area can indicate whether it is a continent, a sea, or an area with a mixture of continents and seas. As a non-limiting example, the area can indicate the ratio of sea to continent. According to one embodiment, the prediction information can include information about time-dependent attributes. For example, the time can be a season, a month, a day, or a year. For example, the time can indicate a specific time period of a day (e.g., late night time, working time). For example, the attribute can include information about the load of the satellite. As a non-limiting example, the load of the satellite can indicate the number of terminals connected to the cells provided by the satellite. The attribute can indicate the per-cell load of the satellite. The satellite can support one or more frequency bands. The attribute can indicate the per-frequency-band (e.g., per-cell) load of the satellite.

[0118] The AMF640 can identify satellites. The said satellites indicate the satellites selected for deactivation among the satellites managed by the AMF640. The AMF640 can identify the satellites to be deactivated among the satellites corresponding to the sector of operation 1001. For example, the satellites corresponding to the said sector can include satellites configured to serve the TAs of a specific TAI list. The specific TA can be related to the middle of the Pacific Ocean. There may be 5 satellites that can provide services at a specific time in the middle of the Pacific Ocean. In such a case, the AMF640 can decide to deactivate 4 satellites. Therefore, the AMF640 can identify the 4 satellites to be deactivated. For example, the satellites corresponding to the said sector can include satellites related to a specific space area. The specific space area can be the middle of the city center. There may be 120 satellites that can be serviced through the said specific space area at a specific time (e.g., late at night). Considering the aspect that the communication volume of users decreases during the late-night time period, the AMF640 can decide to deactivate some satellites. As an example, the AMF640 can identify the satellites to deactivate 60 satellites. For example, the satellites corresponding to the said sector can include satellites configured to serve an area separately defined by the operator. For example, the said area can indicate a desert. Since the number of users is relatively significantly small in the desert, a relatively small number of satellites may be required. There may be 100 satellites that can be serviced in the desert. For power saving of the unnecessary satellites in the desert, the AMF640 can decide to deactivate some satellites. As an example, the AMF640 can identify the satellites to deactivate 90 satellites.

[0119] In operation 1005, the AMF640 can transmit a control signal to satellite 620. The said control signal can instruct the deactivation of satellite 620. The said control signal can include a deactivation command. The said control signal can provide various information not only for activation / deactivation.

[0120] According to one embodiment, the control signal can indicate the deactivation range of the satellite. The satellite is not unconditionally deactivated by the control signal, but can be deactivated by the deactivation range. For example, the deactivation range can be defined in cell units. The control signal can include a cell identifier to be deactivated together with a deactivation command. For example, the deactivation range can be defined in DRB units. The control signal can include a DRB identifier to be deactivated together with a deactivation command. For example, the deactivation range can be defined in SRB units. The control signal can include an SRB identifier to be deactivated together with a deactivation command. For example, the deactivation range can be defined in DU units. The control signal can include a DU ID to be deactivated together with a deactivation command.

[0121] According to one embodiment, the control signal can indicate the deactivation time of the satellite. For example, the control signal can include information about a timer. The information about the timer can indicate the time interval during which the satellite is deactivated (e.g., the length of the timer). The timer can start from the time when the control signal is transmitted. When the timer expires, the satellite can be reactivated.

[0122] According to one embodiment, the control signal can indicate the deactivation area of the satellite. The satellite is not unconditionally deactivated by the control signal, but can be deactivated when entering the deactivation area. For example, the deactivation area can be indicated by a TAI list. The control signal can include the TAI list. For example, the deactivation area can be indicated by a TAI. The control signal can include the TAI. For example, the deactivation area can be indicated by a TAC. The control signal can include the TAC. For example, the deactivation area can be indicated by an identifier of a space area. The control signal can include the identifier. For example, the deactivation area is an area defined by an operator, and the control signal can include the type of the area, an identifier for the area, and / or a list of satellites provided through the area.

[0123] According to one embodiment, the control signal can indicate a frequency band to be deactivated for the satellite. For example, the frequency band can indicate a frequency band for assisting satellite communication. The control signal can indicate a specific band to be deactivated within the frequency band for assisting satellite communication. For example, the frequency band can be associated with a cell. The control signal can indicate a cell to be deactivated among the cells corresponding to the specific frequency band.

[0124] According to one embodiment, the control signal can include information on the type of area where the satellite is deactivated. The satellite is not unconditionally deactivated by the control signal, and the satellite can be deactivated when entering a specific type of area. For example, the type can indicate whether it is a continent, a sea, a city center, an outer area, or the ratio of a terrestrial network to a non-terrestrial network.

[0125] According to one embodiment, the control signal can include information on the cause of the satellite deactivation. The control signal can include information on the cause of why the satellite is deactivated. For example, the cause can be indicated by one of the following values.

[0126] -Deactivation due to orbital movement -Resource optimisation -Reduce load in serving cell、 -User inactivity、 -Service Area Type(e.g., sea、 land、 desert、 island) -Low traffic on cell -Low traffic on frequency band -Low traffic on service area Although the deactivation of a satellite was described as an example in FIG. 10, the embodiments of the present disclosure are not limited thereto. The sectors and prediction information described through FIG. 10 may be used for the activation of a satellite. AMF640 can identify the satellite corresponding to the sector and identify the satellite to be activated among the satellites. AMF640 can transmit a control signal for instructing activation to the satellite.

[0127] Although the operation between AMF640 and satellite 620 was described in FIG. 10, the embodiments of the present disclosure are not limited thereto. Any entity for managing satellites can be used instead of AMF640. For example, if a large number of DUs are connected to a CU and each DU corresponds to a satellite, the CU can identify the satellite to be deactivated (or the satellite to be activated) and transmit a control signal to the DU corresponding to the identified satellite. The control signal can be defined on the F1 interface. An example of a specific message can be defined through FIG. 11b. For example, satellites can form a group. The group can include a master satellite and one or more slave satellites. The master satellite within the group can identify the slave satellite to be deactivated (or the slave satellite to be activated) and transmit a control signal to the identified slave satellite. The control signal can be defined on the XN interface. An example of a specific message can be defined through FIG. 12.

[0128] The deactivation indication information (e.g., "deactivation indication" IE) of the control signal in operation 1005 can be exemplified and displayed in the following format.

[0129] [Table 7] The activation indication information (e.g., "activation indication" IE) of the control signal in operation 1005 can be exemplified and displayed in the following format.

[0130] [Table 8] Figure 11a illustrates an example of signaling through the NG interface to indicate a deactivated satellite. The same reference numerals may represent the application of the same description.

[0131] Referring to Figure 11a, in operation 1101, the AMF 640 can transmit a request message to the satellite 620. The request message can include a deactivation command (or an activation command). The request message can indicate the deactivation scope of the satellite (e.g., cell identifier, DRB identifier, SRB identifier, and / or DU ID). The request message can include information about the deactivation time (or information about the activation time). The request message can include information about the deactivation area (or information about the activation area). The satellite that receives the control signal when entering the deactivation area can be deactivated. The request message can indicate the frequency band to be deactivated (or the frequency band to be activated) of the satellite. The request message can include information about the type of the area where the satellite is deactivated (or the area where the satellite is activated). The request message can include information about the type of the area where the satellite is deactivated. In operation 1103, the satellite 620 can transmit a response message to the AMF 640.

[0132] The request message and the response message can be messages separately defined for satellite deactivation or can be used together with the messages defined in the TS 38.413 standard.

[0133] According to one embodiment, the request message can be a "PDU SESSION RESOURCE SETUP REQUEST" message, and the response message can be a "PDU SESSION RESOURCE SETUP RESPONSE" message.

[0134] [Table 9-01]

[0135]

Table 9-02

[0136] According to one embodiment, the request message may be a "PDU SESSION RESOURCE MODIFY REQUEST" message, and the response message may be a "PDU SESSION RESOURCE MODIFY RESPONSE" message.

[0137]

Table 10-01

[0138]

Table 10-02

[0139] According to one embodiment, the request message may be an "AMF CONFIGURATION UPDATE" message, and the response message may be an "AMF CONFIGURATION UPDATE ACKNOWLEDGE" message.

[0140]

Table 11-01

[0141]

Table 11-02

[0142]

Table 11-03

[0143]

Table 11-04

[0144] FIG. 11b illustrates an example of signaling through the F1 interface for instructing a deactivated satellite. The same reference numerals may represent the application of the same description.

[0145] Referring to FIG. 11b, in operation 1151, gNB-CU 1120 can transmit a request message for waveform setting to gNB-DU 1100 corresponding to a satellite (e.g., satellite 620). Here, gNB-DU 1100 performs the DU function of satellite 620. The request message can include a deactivation command (or an activation command). The request message can indicate the deactivation range of the satellite (e.g., cell identifier, DRB identifier, SRB identifier, and / or DU ID). The request message can include information about the deactivation time (or information about the activation time). The request message can include information about the deactivation area (or information about the activation area). The satellite that receives the control signal when entering the deactivation area can be deactivated. The request message can indicate the frequency band to be deactivated by the satellite (or the frequency band to be activated). The request message can include information about the type of the area where the satellite is deactivated (or the area where the satellite is activated). The request message can include information about the type of the area where the satellite is deactivated. In operation 1153, gNB-DU 1100 corresponding to a satellite (e.g., satellite 620) can transmit a response message to gNB-CU 1120.

[0146] The request message and the response message are messages separately defined for satellite deactivation or can be used together with the messages defined in the TS 38.473 standard.

[0147] According to one embodiment, the request message may be a GNB-CU configuration update message, and the response message may be a gNB-CU configuration update confirmation message. gNB-CU1120 can transmit a GNB-CU configuration update message to gNB-DU1110 through the F1 interface. gNB-DU1110 can transmit a GNB-CU configuration update confirmation message to gNB-CU1120 through the F1 interface. The GNB-CU configuration update message can include at least one of the information in [Table 7] or [Table 8]. For example, the request message can include IEs as exemplified in [Table 12] as follows.

[0148]

Table 12-01

[0149]

Table 12-02

[0150]

Table 12-03

[0151]

Table 12-04

[0152]

Table 12-05

[0153]

Table 12-06

[0154]

Table 12-07

[0155]

Table 12-08

[0156] FIG. 12 illustrates an example of signaling through the XN interface for indicating a deactivated satellite. The same reference numbers may represent the application of the same description. As a link between satellites, an ISL (inter-satellite link) may be utilized. The first base station (e.g., RAN node, gNB) may correspond to satellite 620, and the second base station (e.g., RAN node, gNB) may correspond to the base station 1220 located on the ground.

[0157] Referring to FIG. 12, in operation 1201, satellite 620 can transmit a first message to base station 1220 through the XN interface. Base station 1220 can receive the first message from satellite 620.

[0158] In operation 1203, base station 1220 can transmit a second message to satellite 620 through the XN interface. Satellite 620 can receive the second message from base station 1220.

[0159] According to one embodiment, the first message may be a handover request message, and the second message may be a handover response message. The satellite 620 can transmit a handover request message to the base station 1220 through the XN interface. The base station 1220 can transmit a handover response message to the satellite 620 through the XN interface. The handover request message can include at least one of the information in [Table 7] and [Table 8]. The handover response message can include at least one of the information in [Table 7] and [Table 8]. For example, the first message can include the following IEs illustrated in [Table 13].

[0160]

Table 13-01

[0161]

Table 13-02

[0162]

Table 13-03

[0163]

Table 13-04

[0164]

Table 13-05

[0165] According to one 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 can transmit a cell activation request message to the base station 1220 through the XN interface. The base station 1220 can transmit a cell activation response message to the satellite 620 through the XN interface. The cell activation request message can include at least one of the information in [Table 7] and [Table 8]. The cell activation response message can include at least one of the information in [Table 7] and [Table 8]. For example, the first message can include the following IEs as illustrated in [Table 14].

[0166]

Table 14-01

[0167]

Table 14-02

[0168] According to one 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 can transmit an XN setup request message to the base station 1220 through the XN interface. The base station 1220 can transmit an XN setup response message to the satellite 620 through the XN interface. The XN setup request message can include at least one of the information in [Table 7] and [Table 8]. The XN setup response message can include at least one of the information in [Table 7] and [Table 8]. For example, the first message can include the following IEs as illustrated in [Table 15].

[0169]

Table 15-01

[0170]

Table 15-02

[0171]

Table 15-03

[0172]

Table 15-04

[0173] According to one embodiment, the first message may be an NG-RAN node configuration update message, and the second message may be an NG-RAN node configuration update confirmation message. The satellite 620 can transmit an NG-RAN node configuration update message to the base station 1220 through the XN interface. The base station 1220 can transmit an NG-RAN node configuration update confirmation message to the satellite 620 through the XN interface. The NG-RAN node configuration update message can include at least one of the information in [Table 7] and [Table 8]. The NG-RAN node configuration update confirmation message can include at least one of the information in [Table 7] and [Table 8]. For example, the first message can include IEs as follows exemplified in [Table 16].

[0174]

Table 16-01

[0175]

Table 16-02

[0176]

Table 16-03

[0177]

Table 16-04

[0178]

Table 16-05

[0179]

Table 16-06

[0180]

Table 16-07

[0181]

Table 16-08

[0182] According to one embodiment, the first message may be an S-node addition request message, and the second message may be an S-node addition response message. The satellite 620 can transmit an S-node addition request message to the base station 1220 through the XN interface. The base station 1220 can transmit an S-node addition response message to the satellite 620 through the XN interface. The S-node addition request message can include at least one of the information in [Table 7] and [Table 8]. The S-node addition response message can include at least one of the information in [Table 7] and [Table 8]. For example, the first message can include the following IEs illustrated in [Table 17].

[0183]

Table 17-01

[0184]

Table 17-02

[0185]

Table 17-03

[0186]

Table 17-04

[0187]

Table 17-05

[0188]

Table 17-06

[0189]

Table 17-07

[0190]

Table 17-08

[0191]

Table 17-09

[0192] According to one 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 can transmit an S-node modification request message to the base station 1220 through the XN interface. The base station 1220 can transmit an S-node modification response message to the satellite 620 through the XN interface. The S-node modification request message can include at least one of the information in [Table 7] and [Table 8]. The S-node modification response message can include at least one of the information in [Table 7] and [Table 8]. For example, the first message can include IEs as follows exemplified in [Table 18].

[0193]

Table 18-01

[0194]

Table 18-02

[0195]

Table 18-03

[0196]

Table 18-04

[0197]

Table 18-05

[0198]

Table 18-06

[0199]

Table 18-07

[0200]

Table 18-08

[0201]

Table 18-09

[0202]

Table 18-10

[0203] According to one embodiment, the first message may be an S-node modification request message, and the second message may be an S-node modification confirmation message. The satellite 620 can transmit an S-node modification request message to the base station 1220 through the XN interface. The base station 1220 can transmit an S-node modification confirmation message to the satellite 620 through the XN interface. The S-node modification request message can include at least one of the information in [Table 7] and [Table 8]. The S-node modification confirmation message can include at least one of the information in [Table 7] and [Table 8]. For example, the first message can include the following IEs illustrated in [Table 19].

[0204]

Table 19-01

[0205]

Table 19-02

[0206]

Table 19-03

[0207]

Table 19-04

[0208]

Table 19-05

[0209]

Table 19-06

[0210] FIG. 13 illustrates an example of components of a satellite (e.g., satellite 260, satellite 620). Terms such as “… section” and “… device” used hereinafter mean a unit that processes at least one function or operation, which may be embodied by hardware, software, or a combination of hardware and software.

[0211] Referring to FIG. 13, 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 radio channel. For example, the transceiver 1301 upwardly converts a baseband signal into an RF band signal and then transmits it through an antenna, and downwardly converts an RF band signal received through the antenna into a baseband signal. For example, the transceiver 1301 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0212] The transceiver 1301 can include a number of transmission / reception paths. Further, the transceiver 1301 can include an antenna section. The transceiver 1301 can include at least one antenna array composed of a number of antenna elements. On the hardware side, the transceiver 1301 can be composed of digital circuits and analog circuits (e.g., RFIC (radio frequency integrated circuit)). Here, the digital circuits and analog circuits can be embodied in one package. Also, the transceiver 1301 can include a number of RF chains. The transceiver 1301 can perform beamforming. The transceiver 1301 can apply beamforming weight values to signals in order to impart directivity according to the settings of the processor 1303 to the signals to be transmitted and received. According to one embodiment, the transceiver 1301 can include an RF (radio frequency) block (or RF section).

[0213] The transceiver 1301 can transmit and receive signals over a radio access network. For example, the transceiver 1301 can transmit a downlink signal. The downlink signal can include a synchronization signal (SS), a reference signal (RS) (e.g., CRS (cell-specific reference signal), DM (demodulation)-RS), system information (e.g., MIB, SIB, RMSI (remaining system information), OSI (other system information)), a configuration message, control information, or downlink data, etc. Also, for example, the transceiver 1301 can receive an uplink signal. The uplink signal can include a random access related signal (e.g., a random access preamble (RAP) (or Msg1 (message 1)), Msg3 (message 3)), a reference signal (e.g., SRS (sounding reference signal), DM-RS), or a power headroom report (PHR), etc. Although only the transceiver 1301 is illustrated in FIG. 13, in other embodiments, the satellite 620 can include two or more RF transceivers.

[0214] Processor 1303 controls the overall operation of satellite 620. Processor 1303 may be referred to as a control unit. For example, processor 1303 transmits and receives signals through transceiver 1301. Also, processor 1303 records data in and reads data from memory 1305. And processor 1303 can perform the functions of a protocol stack required by a communication standard. Although only processor 1303 is illustrated in FIG. 13, in other embodiments, satellite 620 may include two or more processors. Processor 1303 is a set of instruction words or code stored in memory 1305, which is at least temporarily a storage space that resides in processor 1303 or stores the instruction words / code, or may be part of the circuitry that constitutes processor 1303. Also, processor 1303 may include various modules for performing communication. Processor 1303 can control satellite 620 to perform the operations according to the embodiments.

[0215] Memory 1305 stores data such as basic programs, application programs, and setting information for the operation of satellite 620. Memory 1305 may be referred to as a storage unit. Memory 1305 may be composed of a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. And memory 1305 provides the data stored upon the request of processor 1303. According to one embodiment, memory 1305 may include a memory for conditions, instructions, or set values related to the SRS transmission method.

[0216] FIG. 14 illustrates an example of the components of a terminal (e.g., UE610). The terminal is exemplified by UE610. UE610 can establish a connection to a gNB (e.g., gNB120) that provides NR access through NTN.

[0217] Referring to FIG. 14, UE610 may include at least one processor 1401, at least one memory 1403, and at least one transceiver 1405. Hereinafter, the components are described in the singular, but the implementation of multiple components or sub-components is not excluded.

[0218] Processor 1401 controls the overall operation of UE610. For example, processor 1401 records data in and reads data from memory 1403. For example, processor 1401 transmits and receives signals through transceiver 1405. Although one processor is illustrated in FIG. 14, embodiments of the present disclosure are not limited thereto. UE610 may include at least one processor to implement embodiments of the present disclosure. Processor 1401 may be referred to as a control unit or control means. According to an embodiment, processor 1401 can control UE610 to perform at least one of the operations or methods according to embodiments of the present disclosure.

[0219] Memory 1403 can store data such as basic programs, application programs, and setting information for the operation of UE610. Memory 1403 can store various data used by at least one component (e.g., transceiver 1405, processor 1401). The data can include, for example, software and input data or output data for related instructions. Memory 1403 may be composed of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. And memory 1403 can provide the data stored at the request of processor 1401.

[0220] Transceiver 1405 performs a function for transmitting and receiving signals through a radio channel. For example, transceiver 1405 performs a conversion function between a baseband signal and a bit sequence according to the physical layer standard of the system. For example, at the time of data transmission, transceiver 1405 generates complex symbols by encoding and modulating the transmission bit sequence. Also, at the time of data reception, transceiver 1405 restores the received bit sequence through demodulation and decoding of the baseband signal. Also, transceiver 1405 upwardly converts the baseband signal into an RF (radio frequency) band signal and then transmits it through an antenna, and downwardly converts the RF band signal received through the antenna into a baseband signal.

[0221] For this purpose, the transceiver 1405 can include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC (digital to analog convertor), an ADC (analog to digital convertor), etc. Further, the transceiver 1405 can include a number of transmission and reception paths. Consequently, the transceiver 1405 can include at least one antenna array composed of a number of antenna elements. On the hardware side, the transceiver 1405 can be composed of a digital unit and an analog unit, and the analog unit can be composed of a number of sub-units according to the operating power, operating frequency, etc.

[0222] As described above, the transceiver 1405 transmits and receives signals. Accordingly, the transceiver 1405 may be referred to as a "transmission unit", a "reception unit", or a "transceiver unit". Also, in the following description, transmission and reception performed through a wireless channel, a backhaul network, an optical cable, Ethernet, or other wired paths are used in the sense of including that the transceiver 1405 performs the processing as described above. According to one embodiment, the transceiver 1405 can provide an interface for communicating with other nodes in the network. That is, the transceiver 1405 can convert a bit stream transmitted from the UE 610 to other nodes, such as other connected nodes, other base stations, upper nodes, a core network, etc., into a physical signal, and convert a physical signal received from other nodes into a bit stream.

[0223] In describing embodiments of the present disclosure, terms and messages defined by 3GPP are used to describe messages between a satellite (e.g., satellite 620) and a terminal (e.g., UE 610), but embodiments of the present disclosure are not limited thereto. Of course, terms and messages having a technical meaning equivalent to the above-described terms and messages may be used as an alternative. Not only that, as the satellite, not only gNB, gNB-CU, gNB-DU, but also gNB-CU-CP (control plane) (e.g., C-plane in FIG. 3a) and gNB-CU-UP (user plane) (e.g., U-plane in FIG. 3b)) can be used. In addition, not only is the satellite used as a base station (e.g., gNB) or a part of the base station (e.g., DU), but also a core network entity (e.g., AMF 235) connected to the base station may be implemented by the satellite. For example, communication between a satellite operating as AMF 235 and satellite 620 may be defined. For example, a logical node including AMF 235 and gNB 120 may be implemented in one satellite. Through network virtualization, by being implemented in software, separate logical nodes may be arranged within one hardware satellite.

[0224] In an embodiment, a satellite device for providing NTN access is provided. The device can include a memory containing instructions, at least one processor, and at least one transceiver. When the instructions are executed by the at least one processor, the device can transmit, through the at least one transceiver, a message containing information indicating whether to activate transform precoding for downlink transmission to a terminal, generate a downlink signal based on the information, and cause the downlink signal to be transmitted to the terminal through the at least one transceiver. When the information indicates activation of the transform precoding, the downlink signal is generated through a DFT-S (discrete fourier transform-spreading) OFDM (orthogonal frequency division multiplexing) scheme, and when the information does not indicate activation of the transform precoding, the downlink signal can be generated through a CP (cyclic prefix)-OFDM scheme.

[0225] For example, when the instructions are executed by the at least one processor, the device can be caused to receive, from the terminal, capability information indicating that the terminal supports transform precoding for downlink transmission at the satellite.

[0226] For example, the message can include physical downlink shared channel (PDSCH) configuration information related to a non-terrestrial network (NTN). The PDSCH configuration information can include information indicating whether the transform precoding for the PDSCH is activated, first modulation and coding scheme (MCS) table information, and second MCS table information. The first MCS table information can indicate the MCS table used when the transform precoding is activated. The second MCS table information can indicate the MCS table used when the transform precoding is deactivated.

[0227] In an embodiment, a terminal for communicating with a satellite in an NTN access is provided. The terminal can include a memory including instructions, at least one processor, and at least one transceiver. When the instructions are executed by the at least one processor, the terminal can receive, through the at least one transceiver, a message including information indicating whether to activate transform precoding for downlink transmission from the satellite, and cause the terminal to receive the downlink signal from the satellite through the at least one transceiver based on the information. When the information indicates activation of the transform precoding, the downlink signal can be received through a discrete fourier transform-spreading (DFT-S) orthogonal frequency division multiplexing (OFDM) scheme. When the information does not indicate activation of the transform precoding, the downlink signal can be received through a cyclic prefix (CP)-OFDM scheme.

[0228] For example, when the instruction is executed by the at least one processor, it can cause the terminal to transmit, to the satellite, capability information indicating that the satellite assists the terminal in performing transform precoding for downlink transmission.

[0229] For example, the message can include physical downlink shared channel (PDSCH) configuration information related to a non-terrestrial network (NTN). The PDSCH configuration information can include information indicating whether transform precoding for the PDSCH is activated, first MCS table information, and second MCS table information. The first MCS table information can indicate an MCS table used when the transform precoding is activated. The second MCS table information can indicate an MCS table used when the transform precoding is deactivated.

[0230] In an embodiment, a network device that communicates with a satellite to provide NTN access is provided. The network device can include a memory including instructions, at least one processor, and at least one transceiver. When the instructions are executed by the at least one processor, the network device can identify a plurality of satellites corresponding to sectors related to a specific area, identify a first satellite to be deactivated among the plurality of satellites based on prediction information related to a specific time, and cause the at least one transceiver to transmit a message instructing the first satellite to be deactivated to the first satellite.

[0231] For example, the message includes at least one of information about a cell to be deactivated, information about a DRB (data radio bearer) to be deactivated, information about an SRB (signaling radio bearer) to be deactivated, information about a DU (distributed unit) to be deactivated, or information about a frequency band to be deactivated. For example, the message can include information about a service area to be deactivated and information about the type of the service area. The service area to be deactivated can include at least one of an area specified by a TAI (tracking area identity), an area specified by a TAI list, an area specified by a TAC (tracking area code), or a space area indicating one of the celestial spaces. The type can indicate one of a plurality of types of the service area. The plurality of types can include at least one of sea, continent, island, or desert.

[0232] For example, the message can include information about a timer for deactivation. The timer starts from the time when the message is received, and when the timer expires, the state of the satellite can be changed from the deactivated state to the active state.

[0233] For example, the message can include information about the cause of deactivation. The cause can indicate one of a plurality of causes. The plurality of causes can include at least one of deactivation due to orbital movement, resource optimization, user inactivity, service area type, low cell traffic, or low service area traffic. For example, the network device can be a network entity operating with an AMF (access and mobility management function) or a CU (central unit).

[0234] For example, when the instruction is executed by the at least one processor, it can cause the network device to transmit, through the at least one transceiver, other control signals for instructing the first satellite to activate the first satellite.

[0235] In an embodiment, a satellite device for providing NTN access is provided. The device can include a memory including instructions, at least one processor, and at least one transceiver. When the instructions are executed by the at least one processor, the satellite can receive, through the at least one transceiver, a message instructing deactivation of the satellite from a network device, and in response to the message, cause at least one of the components of the satellite to be deactivated. The deactivation of the satellite can be associated with a specific area and a specific time.

[0236] For example, the message can include at least one of information about a cell to be deactivated, information about a DRB (data radio bearer) to be deactivated, information about an SRB (signaling radio bearer) to be deactivated, information about a DU (distributed unit) to be deactivated, or information about a frequency band to be deactivated. For example, the message can include information about a service area to be deactivated and information about the type of the service area. The service area to be deactivated can include at least one of an area specified by a TAI (tracking area identity), an area specified by a TAI list, an area specified by a TAC (tracking area code), or a space area indicating one of the celestial spaces. The type can indicate one of a plurality of types of the service area. The plurality of types can include at least one of sea, continent, island, or desert.

[0237] For example, the message can include information for a timer for deactivation. The timer is started from the time when the message is received, and when the timer expires, the state of the satellite can be changed from the deactivated state to the activated state.

[0238] For example, the message can include information about the cause of deactivation. The cause can indicate one of a plurality of causes. The plurality of causes can include at least one of deactivation due to orbit movement, resource optimization, user inactivity, service area type, low traffic in cells, or low traffic in service areas. For example, the network device can be a network entity operating as an AMF (access and mobility management function) or a CU (central unit).

[0239] For example, when the instruction is executed by the at least one processor, the satellite can receive, through the at least one transceiver, another control signal for activating the satellite from the network device, and in response to the other control signal, cause at least one of the components of the satellite to be activated.

[0240] The method according to the claims or embodiments described in the specification of the present disclosure can be implemented in the form of hardware, software, or a combination of hardware and software.

[0241] When implemented in software, 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 for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to perform the methods according to the embodiments described in the claims or specification of the present disclosure.

[0242] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc-ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes. Or they may be stored in a memory composed of some or all of these combinations. Also, there may be a large number of each constituent memory.

[0243] Also, the program can be stored in an attachable storage device that can be accessed through a communication network such as the Internet, Intranet, LAN (local area network), WAN (wide area network), or SAN (storage area network), or a communication network composed of a combination of these. Such a storage device can be connected to the device that implements the embodiments of the present disclosure through an external port. Also, a separate storage device on the communication network may be connected to the device that implements the embodiments of the present disclosure.

[0244] In the specific embodiments of the present disclosure described above, the components included in the disclosure are represented in singular or plural by the specific embodiments presented. However, the singular or plural expressions are selected to conform to the situations presented for the convenience of explanation, and the present disclosure is not limited to singular or plural components, and even components expressed in plural may be composed of a single one, or components expressed in singular may be composed of a plurality.

[0245] On the other hand, although the detailed description of the present disclosure has been made with respect to specific embodiments, it goes without saying that various modifications are possible within the scope not departing from the present disclosure.

Claims

1. A satellite device for providing NTN access, comprising: A memory containing instructions; at least one processor; and at least one transceiver; The instructions, when executed by the at least one processor, cause the apparatus to: Transmitting a message including information indicating whether transform precoding of downlink transmission is activated to a terminal through the at least one transceiver; generating a downlink signal based on said information; causing the terminal to transmit the downlink signal through the at least one transceiver; If the information indicates activation of the transform precoding, the downlink signal is generated through a discrete fourier transform-spreading (DFT-S) orthogonal frequency division multiplexing (OFDM) scheme; If the information does not indicate activation of the transform precoding, the downlink signal is generated through a cyclic prefix (CP)-OFDM scheme.

2. The instructions, when executed by the at least one processor, cause the apparatus to: The apparatus of claim 1 , further comprising: causing the satellite to receive, from the terminal, capability information indicating that the terminal supports transform precoding of downlink transmissions.

3. The message includes PDSCH (physical downlink shared channel) configuration information related to NTN (non-terrestrial network), The PDSCH configuration information includes information indicating whether or not the transform precoding for the PDSCH is activated, first MCS table information, and second MCS table information, The first MCS table information indicates an MCS table used when the transform precoding is activated, The apparatus of claim 1 , wherein the second MCS table information indicates an MCS table to be used when the transform precoding is deactivated.

4. In a terminal for communication with a satellite via NTN access, A memory containing instructions; at least one processor; and at least one transceiver; The instructions, when executed by the at least one processor, cause the terminal to: receiving a message from the satellite via the at least one transceiver, the message including information indicating whether or not transform precoding of a downlink transmission is activated; causing the downlink signal to be received from the satellite via the at least one transceiver based on the information; If the information indicates activation of the transform precoding, the downlink signal is received through a discrete fourier transform-spreading (DFT-S) orthogonal frequency division multiplexing (OFDM) scheme; If the information does not indicate activation of the transform precoding, the downlink signal is received via a cyclic prefix (CP)-OFDM scheme.

5. The instructions, when executed by the at least one processor, cause the apparatus to: The terminal of claim 4 , further comprising: causing the satellite to transmit capability information indicating that the terminal supports transform precoding of downlink transmissions to the satellite.

6. The message includes PDSCH (physical downlink shared channel) configuration information related to NTN (non-terrestrial network), The PDSCH configuration information includes information indicating whether or not the transform precoding for the PDSCH is activated, first MCS table information, and second MCS table information, The first MCS table information indicates an MCS table used when the transform precoding is activated, The terminal of claim 4 , wherein the second MCS table information indicates an MCS table used when the transform precoding is deactivated.

7. A network device that communicates with a satellite to provide NTN access, A memory containing instructions; at least one processor; and at least one transceiver; The instructions, when executed by the at least one processor, cause the network device to: Identifying a plurality of satellites corresponding to a particular geographic region; identifying a first satellite among the plurality of satellites to be deactivated based on the forecast information associated with a particular time; A network device causing the first satellite to transmit a message control signal through the at least one transceiver instructing the first satellite to be deactivated.

8. The network device of claim 7, wherein the message includes at least one of information on a deactivated cell, information on a deactivated data radio bearer (DRB), information on a deactivated signaling radio bearer (SRB), information on a deactivated distributed unit (DU), and information on a deactivated frequency band.

9. The message includes information on a service area to be deactivated and information on a type of the service area, The inactivated service area includes at least one of an area identified by a tracking area identity (TAI), an area identified by a TAI list, an area identified by a tracking area code (TAC), or a space area indicating one of the celestial space areas; The type indicates one of a plurality of types of the service area, The network device of claim 7 , wherein the plurality of types includes at least one of an ocean, a continent, an island, and a desert.

10. The message includes information regarding a deactivation timer, 8. The network device according to claim 7, wherein the timer is started from the time when the message is received, and when the timer expires, the state of the satellite is changed from an inactive state to an active state.

11. The message includes information regarding the cause of deactivation, The cause indicates one of a plurality of causes, The network device of claim 7, wherein the plurality of causes include at least one of inactivation due to orbital mobility, resource optimization, user inactivity, service area type, low traffic in a cell, or low traffic in a service area.

12. The network device of claim 7, wherein the network device is a network entity that operates as an access and mobility management function (AMF) or a central unit (CU).

13. The instructions, when executed by the at least one processor, cause the network device to:

8. The network device of claim 7, further comprising: causing said first satellite to transmit through said at least one transceiver another control signal directing activation of said first satellite.

14. A satellite device for providing NTN access, comprising: A memory containing instructions; at least one processor; and at least one transceiver; The instructions, when executed by the at least one processor, cause the satellite to: receiving a message from a network device via the at least one transceiver indicating deactivation of the satellite; in response to said message, causing at least one of said satellite components to be deactivated; The deactivation of said satellites is associated with a particular region and a particular time.

15. The message includes at least one of information on a deactivated cell, information on a deactivated data radio bearer (DRB), information on a deactivated signaling radio bearer (SRB), information on a deactivated distributed unit (DU), and information on a deactivated frequency band.

16. The message includes information on a service area to be deactivated and information on a type of the service area, The inactivated service area includes at least one of an area identified by a tracking area identity (TAI), an area identified by a TAI list, an area identified by a tracking area code (TAC), or a space area indicating one of the celestial space areas; The type indicates one of a plurality of types of the service area, The apparatus of claim 14 , wherein the plurality of types includes at least one of an ocean, a continent, an island, or a desert.

17. The message includes information regarding a deactivation timer, 15. The apparatus of claim 14, wherein the timer is started upon receipt of the message, and when the timer expires, the state of the satellite is changed from an inactive state to an active state.

18. The message includes information regarding the cause of deactivation, The cause indicates one of a plurality of causes, The apparatus of claim 14, wherein the plurality of causes include at least one of inactivation due to orbital movement, resource optimization, user inactivity, service area type, low traffic in a cell, or low traffic in a service area.

19. The device of claim 14, wherein the network device is a network entity that operates in an access and mobility management function (AMF) or a central unit (CU).

20. The instructions, when executed by the at least one processor, cause the satellite to: receiving another control signal from the network device via the at least one transceiver, the control signal instructing activation of the satellite; 15. The apparatus of claim 14, responsive to said other control signal to cause said at least one of said satellite components to be activated.

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