Method, user equipment, processing device, and storage medium for receiving downlink signal, and method, base station, processing device, and storage medium for transmitting downlink signal

Abstract

A UE attempts to detect an SSB on a first frequency band supporting a TN and an NTN, and performs an initial access procedure on the basis of the detected SSB, wherein the attempt to detect the SSB may be performed with priority on a cell having a high priority from among a TN cell and an NTN cell on the basis of priorities that are set for the TN cell and the NTN cell.

Description

Method for receiving a downlink signal, user device, processing device and storage medium, and method for transmitting a downlink signal, base station, processing device and storage medium

[0001] This specification relates to a wireless communication system.

[0002] Various devices and technologies, such as machine-to-machine (M2M) communication, machine-type communication (MTC), and smartphones and tablet PCs (personal computers) that require high data transmission rates, are emerging and becoming widespread. Consequently, the amount of data required to be processed on cellular networks is rapidly increasing. To meet this rapidly increasing data processing demand, technologies such as carrier aggregation and cognitive radio are being developed to efficiently utilize more frequency bands, while multi-antenna technology and multi-base station (BS) cooperation technology are being developed to increase the data capacity transmitted within a limited frequency range.

[0003] Recently, support for wireless communication services through non-terrestrial networks (NTNs) has been considered in order to provide wireless communication services in places where terrestrial connections are technically very difficult or expensive to provide wireless communication services through terrestrial networks.

[0004] A method is required to accurately and efficiently provide wireless communication signals to UEs via airborne platforms or space.

[0005] Additionally, a method for efficient coexistence of terrestrial networks and NTNs is required.

[0006] The technical problems to be solved by this specification are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field related to this specification from the detailed description below.

[0007] A method for a terminal to receive a downlink signal in a wireless communication system according to one aspect comprises the steps of: attempting to detect a synchronization block (SSB) on a first frequency band in which a terrestrial network (TN) cell and a non-terrestrial network (NTN) cell are supported; and performing an initial access procedure based on the detected SSB, wherein the attempt to detect the SSB may be performed with priority on a cell having a higher priority among the TN cell and the NTN cell based on priorities set for the TN cell and the NTN cell.

[0008] Alternatively, based on the TN cell having the higher priority, the attempt to detect the SSB is performed in the order of the TN cell to the NTN cell, and based on the detection of both the first SSB for the TN cell and the second SSB for the NTN cell, the initial access procedure is characterized in that it is performed for one cell determined among the TN cell and the NTN cell based on the first threshold set for the quality of the SSB and the priority.

[0009] Alternatively, based on the quality of the second SSB being higher than the quality of the first SSB by the first threshold, the one cell is determined as the NTN cell even if the TN has a higher priority.

[0010] Alternatively, based on the quality of the first SSB not being lower than the quality of the second SSB by the first threshold, the one cell is determined as the TN cell having the higher priority.

[0011] Alternatively, the terminal is characterized in that the SSB is detected, including indication information indicating the existence of a low-priority cell in the SSB and a second threshold, and the quality of the SSB is lower than the second threshold, and the terminal attempts to detect the SSB for the low-priority cell among the TN cell and the NTN cell.

[0012] Alternatively, the priority is characterized in that it is set based on at least one of the type, mobility, communication environment and service requirements of the terminal.

[0013] Alternatively, based on whether the terminal type is mMTC (massive Machine Type Communications) type, V2X (Vehicle to Everything) type, or NB-IoT (Narrowband Internet of things) type, the NTN is characterized in that a higher priority is set than the TN.

[0014] In another aspect, a terminal for receiving a downlink signal in a wireless communication system includes at least one transceiver; at least one processor; and at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations including: attempting to detect a synchronization block (SSB) on a specific frequency band supporting a terrestrial network (TN) and a non-terrestrial network (NTN), and performing an initial access procedure based on the detected SSB, wherein the attempt to detect the SSB may be performed with priority on a cell having a higher priority among the TN cell and the NTN cell based on priorities set for the TN cell and the NTN cell.

[0015] The above problem solving methods are only some of the examples in this specification, and various examples reflecting the technical features of this specification can be derived and understood by a person having ordinary knowledge in the relevant technical field based on the detailed description below.

[0016] According to some implementations of this specification, wireless communication signals can be efficiently transmitted and received via airborne platforms or space. This can increase the overall throughput of a wireless communication system.

[0017] According to some implementations of this specification, continuity of wireless communication services can be ensured, reliability of wireless communication services can be enhanced through connectivity between various access technologies, and network resilience and reliability against disasters can be improved.

[0018] According to some implementations of this specification, coexistence of non-terrestrial networks (NTNs) and terrestrial networks (NTs) may be supported.

[0019] According to some implementations of this specification, a UE can effectively detect a synchronization signal block (SSB) even when coexisting on NTN and TN frequency bands.

[0020] The effects according to various embodiments are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art related to the present specification from the detailed description below.

[0021] The drawings attached to this specification are intended to provide an understanding of the present invention, illustrate various embodiments of the present invention, and together with the description of the specification serve to explain the principles of the present invention.

[0022] Figure 1 illustrates an example of a communication system 1 to which implementations of the present specification can be applied.

[0023] FIG. 2 is a block diagram illustrating examples of communication devices capable of performing a method according to the present specification.

[0024] Figure 3 illustrates an example of a frame structure available in a 3GPP-based wireless communication system.

[0025] Figure 4 illustrates an example of a resource grid of slots.

[0026] Figure 5 illustrates an example of multi-beam operation in a 3GPP-based system.

[0027] Figure 6 illustrates an example of SS / PBCH blocks (SSBs) being transmitted on a cell.

[0028] Figure 7 illustrates an example of a non-terrestrial network (NTN) structure.

[0029] Figure 8 illustrates a synchronous raster and a channel raster used in some implementations.

[0030] Figure 9 illustrates the SSB structure.

[0031] Figure 10 illustrates a situation where a terrestrial network (TN) and a non-terrestrial network (NTN) coexist.

[0032] FIG. 11 and FIG. 12 are diagrams for explaining how a terminal attempts to detect SSB based on priority.

[0033] FIG. 13 is a diagram for explaining a method for setting / determining priorities between the TN cell and the NTN cell.

[0034] FIGS. 14 to 16 are diagrams for explaining a method for the terminal to perform cell search in a first frequency band where NTN cells and TN cells coexist.

[0035] Hereinafter, implementations according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description provided below, together with the accompanying drawings, is intended to describe exemplary implementations of the present disclosure and is not intended to represent the only possible implementations of the present disclosure. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, one of ordinary skill in the art will appreciate that the present disclosure may be practiced without these specific details.

[0036] In some cases, to avoid ambiguity in the concepts of this specification, known structures and devices may be omitted or illustrated in block diagram form focusing on the core functions of each structure and device. Furthermore, the same components are described using the same drawing reference numerals throughout this specification.

[0037] The techniques, devices, and systems described below can be applied to various wireless multiple access systems.

[0038] For convenience of explanation, the following description is based on a 3rd Generation Partnership Project (3GPP)-based communication system. However, the technical features of this specification are not limited thereto. For example, although the detailed description below is based on 3rd Generation Partnership Project (3GPP) LTE or 5G technology, some implementations of this specification are applicable to any other mobile communication system and systems to be introduced in the future (e.g., 6G), except for features specific to 3GPP LTE / 5G.

[0039] For terms and technologies used in this specification that are not specifically explained, refer to 3GPP-based standard documents, for example, 3GPP TS 23.304, 3GPP TS 23.285, 3GPP TS 23.287, 3GPP TS 24.587, 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.300, 3GPP TS 36.321, 3GPP 36.322, 3GPP TS 36.323, 3GPP TS and 3GPP TS 36.331, 3GPP TS 37.213, 3GPP TS 38.211, 3GPP TS 38.212, See also 3GPP TS 38.213, 3GPP TS 38.214, 3GPP TS 38.300, 3GPP TS 38.321, 3GPP TS 38.322, 3GPP TS 38.323, and 3GPP TS 38.331.

[0040] In the examples of this specification described below, the expression "assumes" that a device "assumes" may mean that the entity transmitting the channel transmits the channel in a manner consistent with the "assume." The entity receiving the channel may mean that, under the assumption that the channel was transmitted in a manner consistent with the "assume," the entity receiving the channel receives or decodes the channel in a manner consistent with the "assume."

[0041] In this specification, UE may be fixed or mobile, and includes various devices that communicate with a BS (base station, BS) to transmit and / or receive user data and / or various control information. UE may be referred to as (Terminal Equipment), MS (Mobile Station), MT (Mobile Terminal), UT (User Terminal), etc. In addition, in this specification, BS generally refers to a fixed station that communicates with UE and / or other BS, and exchanges various data and control information by communicating with UE and other BS. BS may be referred to by other terms such as ABS (Advanced Base Station), NB (Node-B), eNB (evolved-NodeB), gNB, BTS (Base Transceiver System), Access Point, PS (Processing Server), etc. For convenience of explanation, base stations are collectively referred to as BSs regardless of the type or version of communication technology.

[0042] In this specification, a "node" refers to a fixed point capable of transmitting and receiving wireless signals by communicating with a UE. Various types of BSs, regardless of their designation, can be used as nodes. Each node is equipped with at least one antenna. The antenna may refer to a physical antenna, an antenna port, a virtual antenna, or an antenna group. A node is also referred to as a "point."

[0043] Meanwhile, 3GPP-based communication systems use the concept of cells to manage wireless resources. Cells associated with wireless resources are distinct from cells within a geographic area. A "cell" within a geographic area can be understood as the coverage within which a node can provide services using a carrier, while a "cell" within a wireless resource is associated with a bandwidth (BW), which is the frequency range configured by the carrier. Downlink coverage, the range within which a node can transmit valid signals, and uplink coverage, the range within which a node can receive valid signals from a UE, depend on the carrier carrying the signals. Therefore, the coverage of a node is often associated with the coverage of the "cell" within which the wireless resources are used. Therefore, the term "cell" can sometimes refer to the coverage of a service provided by a node, sometimes to a wireless resource, and sometimes to the range within which a signal using the wireless resource can reach with effective intensity.

[0044] A "cell" associated with wireless resources can be defined as a combination of downlink resources (DL resources) and uplink resources (UL resources), i.e., a combination of a DL component carrier (CC) and an UL CC. A cell can be configured with only DL resources or a combination of DL resources and UL resources. When carrier aggregation is supported, the linkage between the carrier frequency of the DL resources (or DL ​​CC) and the carrier frequency of the UL resources (or UL CC) can be indicated by system information. Here, the carrier frequency can be the same as or different from the center frequency of each cell or CC.

[0045] In a wireless communication system, a UE receives information from a base station (BS) via the downlink (DL), and the UE transmits information to the base station via the uplink (UL). The information transmitted and / or received by the BS and UE includes data and various control information, and various physical channels exist depending on the type and purpose of the information they transmit and / or receive.

[0046] 3GPP-based communication standards define downlink physical channels corresponding to resource elements that carry information originating from higher layers, and downlink physical signals corresponding to resource elements that are used by the physical layer but do not carry information originating from higher layers. For example, the physical downlink shared channel (PDSCH), physical broadcast channel (PBCH), and physical downlink control channel (PDCCH) are defined as downlink physical channels, and reference signals and synchronization signals are defined as downlink physical signals. A reference signal (RS), also referred to as a pilot, refers to a signal with a predefined special waveform that is known to the BS and UE. For example, the demodulation reference signal (DMRS) and the channel state information RS (CSI-RS) are defined as downlink reference signals. 3GPP-based communication standards define uplink physical channels corresponding to resource elements that carry information originating from higher layers, and uplink physical signals corresponding to resource elements that are used by the physical layer but do not carry information originating from higher layers.For example, a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and a physical random access channel (PRACH) are defined as uplink physical channels, and a demodulation reference signal (DMRS) for uplink control / data signals and a sounding reference signal (SRS) used for uplink channel measurement are defined.

[0047] In this specification, PDCCH refers to a set of time-frequency resources (e.g., resource elements (REs)) that carry downlink control information (DCI), and PDSCH refers to a set of time-frequency resources that carry downlink data. In addition, PUCCH, PUSCH, and PRACH refer to sets of time-frequency resources that carry uplink control information (UCI), uplink data, and random access preamble, respectively (respectively). Hereinafter, the expression that a UE / BS transmits / receives a PUCCH / PUSCH / PRACH is used with the same meaning as that UCI / uplink data / random access preamble are transmitted / received on or through the PUCCH / PUSCH / PRACH, respectively. Additionally, the expression that BS / UE transmits / receives PBCH / PDCCH / PDSCH is used with the same meaning as transmitting / receiving broadcast information / DCI / downlink data on or through PBCH / PDCCH / PDSCH, respectively.

[0048] In this specification, radio resources (e.g., time-frequency resources) scheduled or set by the BS to the UE for transmission or reception of PUCCH / PUSCH / PDSCH are also referred to as PUCCH / PUSCH / PDSCH resources.

[0049] Since a communication device receives physical channels and / or physical signals in the form of radio signals on a cell, it cannot selectively receive only radio signals containing only a specific physical channel or a specific physical signal through a radio frequency (RF) receiver, nor can it selectively receive only radio signals excluding only a specific physical channel or a specific physical signal through an RF receiver. In actual operation, the communication device first receives radio signals on a cell through an RF receiver, converts the radio signals, which are RF band signals, into baseband signals, and decodes the physical signals and / or physical channels within the baseband signals using one or more processors. Therefore, in some implementations of the present specification, not receiving a physical signal and / or a physical channel may not actually mean that the communication device does not receive radio signals containing the physical signal and / or physical channel at all, but may mean that it does not attempt to recover the physical signal and / or physical channel from the radio signals, for example, it does not attempt to decode the physical signal and / or the physical channel.

[0050] Figure 1 is an example of a communication system 1 to which implementations of the present specification can be applied.

[0051] Referring to FIG. 1, the communication system (1) applied to the present specification includes a wireless device, a BS, and a network. Here, the wireless device may refer to a device that performs communication using a wireless access technology (e.g., 5G NR (New RAT), LTE (e.g., E-UTRA), WiFi, or 6G to be introduced in the future).

[0052] Although not limited thereto, the wireless devices may include a robot (100a), a vehicle (100b-1, 100b-2, 100b-3, 100b-4), an XR (eXtended Reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Things) device (100f), and an AI device / server (400). For example, the vehicles may include a ground vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing communication between vehicles, etc. Here, the vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone) and an Urban Air Mobility (UAM) (e.g., an unmanned aerial vehicle). The XR devices may include an AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) device. Mobile devices may include smartphones, smart pads, wearable devices (e.g., smartwatches, smart glasses), and computers (e.g., laptops). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors, smart meters, and the like. For example, BSs and networks can also be implemented using wireless devices, and a specific wireless device may act as a BS / network node for other wireless devices.

[0053] Wireless devices (100a to 100f) can be connected to a network through a BS (200). Artificial Intelligence (AI) technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) through a network. The wireless devices (100a to 100f) can communicate with each other through the BS (200) / network, but can also communicate directly (e.g., sidelink communication) without going through the BS / network. For example, the vehicles (100b-1, 100b-2, 100b-3, 100b-4) can communicate directly (e.g., V2V (Vehicle to Vehicle) / V2X (Vehicle to everything) communication). Additionally, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0054] Wireless communication / connection can be established between wireless devices (100a~100f) / BS(200) - BS(200) / wireless devices (100a~100f). Here, the wireless communication / connection can be achieved through various wireless access technologies (e.g., 5G NR) for uplink / downlink communication (UL / DL) and sidelink communication (SL) (or D2D communication). Through the wireless communication / connection (UL / DL, SL), the wireless device and the BS / wireless device can transmit / receive wireless signals to / from each other. To this end, at least some of various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes can be performed based on various proposals of the present specification.

[0055] FIG. 2 is a block diagram illustrating examples of communication devices capable of performing a method according to the present specification. Referring to FIG. 2, a first wireless device (100) and a second wireless device (200) can transmit and / or receive wireless signals via various wireless access technologies. Here, {the first wireless device (100), the second wireless device (200)} can correspond to {the wireless device (100x), the BS (200)} and / or {the wireless device (100x), the wireless device (100x)} of FIG. 1.

[0056] Each of the first wireless device (100) and the second wireless device (200) includes one or more processors (102, 202) and one or more memories (104, 204), and may further include one or more transceivers (106, 206) and / or one or more antennas (108). The processors (102, 202) control the memories (104, 204) and / or the transceivers (106, 206), and may be configured to implement the functions, procedures, and / or methods described / suggested below. For example, the processors (102, 202) may process information in the memories (104, 204) to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceivers (106, 206). In addition, the processor (102, 202) may receive a wireless signal including second information / signal through the transceiver (106, 206), and then store information obtained from signal processing of the second information / signal in the memory (104, 204). The memory (104, 204) may be connected to the processor (102, 202) and may store various information related to the operation of the processor (102, 202). For example, the memory (104, 204) may perform some or all of the processes controlled by the processor (102, 202), or store software code including commands for performing the procedures and / or methods described / proposed below. Here, the processor (102, 202) and the memory (104, 204) may be part of a communication modem / circuit / chip designed to implement wireless communication technology. A transceiver (106, 206) may be connected to a processor (102, 202) and may transmit and / or receive wireless signals via one or more antennas (108, 208). The transceiver (106, 206) may include a transmitter and / or a receiver.

[0057] Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and a service data adaptation protocol (SDAP) layer). One or more processors (102, 202) may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs) in accordance with the functions, procedures, proposals, and / or methods disclosed herein. One or more processors (102, 202) may generate messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein. One or more processors (102, 202) may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) may receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein.

[0058] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the functions, procedures, proposals, and / or methods disclosed herein may be included in one or more processors (102, 202) or stored in one or more memories (104, 204) and executed by one or more processors (102, 202). The functions, procedures, proposals, and / or methods disclosed herein may be implemented using firmware or software in the form of codes, instructions, and / or sets of instructions.

[0059] One or more memories (104, 204) may be connected to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (104, 204) may be located internally and / or externally to one or more processors (102, 202). Additionally, one or more memories (104, 204) may be connected to one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0060] One or more transceivers (106, 206) may transmit / receive user data, control information, wireless signals / channels, etc., referred to in the methods and / or flowcharts of the present specification, to / from one or more other devices. In addition, one or more processors (102, 202) may control one or more transceivers (106, 206) to transmit / receive user data, control information, or wireless signals to / from one or more other devices. In addition, one or more transceivers (106, 206) may be connected to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and / or receive user data, control information, wireless signals / channels, etc., referred to in the functions, procedures, proposals, methods, and / or flowcharts of the present specification, via one or more antennas (108, 208). In this specification, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) may convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals / channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or a filter.

[0061] According to an example, the first wireless device (100) or terminal may include a processor (102) and a memory (104) connected to an RF transceiver (106). The memory (104) may include at least one program capable of performing operations related to the embodiments described in FIGS. 10 to 15 to be described later. Specifically, the operations include attempting to detect a synchronization block (SSB) on a specific frequency band supporting a terrestrial network (TN) and a non-terrestrial network (NTN), and performing an initial access procedure based on the detected SSB, wherein the attempt to detect the SSB may be performed with priority on a network cell having a higher priority among the TN cell and the NTN cell based on priorities set for the TN cell and the NTN cell.

[0062] In this specification, at least one memory (104, 204) can store instructions or programs, which, when executed, cause at least one processor (102, 202) operably connected to the at least one memory to perform operations according to some embodiments or implementations of the present specification.

[0063] In this specification, a computer-readable (non-transitory) storage medium can store at least one instruction or computer program, which when executed by at least one processor causes the at least one processor to perform operations according to some embodiments or implementations of the present specification.

[0064] Figure 3 illustrates an example of a frame structure available in a 3GPP-based wireless communication system.

[0065] The structure of the frame in FIG. 3 is merely an example, and the number of subframes, slots, and symbols in the frame may vary. In some wireless communication systems, OFDM numerologies (e.g., subcarrier spacing (SCS)) may be set differently between multiple cells aggregated to a single UE. Accordingly, the (absolute time) duration of a time resource (e.g., subframe, slot, or transmission time interval (TTI)) composed of the same number of symbols may be set differently between the aggregated cells. Here, the symbol may include an OFDM symbol (or a cyclic prefix - orthogonal frequency division multiplexing (CP-OFDM) symbol), an SC-FDMA symbol (or a discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbol). In this specification, the terms symbol, OFDM-based symbol, OFDM symbol, CP-OFDM symbol and DFT-s-OFDM symbol may be interchangeable.

[0066] Referring to Figure 3, uplink and downlink transmissions are organized into frames. Each frame is T f = (△f max *N f / 100)*T c = 10 ms duration, where T is the basic time unit. c = 1 / (△f max *N f ) and △f max = 480*103 Hz, and N f =4096. For reference, the sampling time T s = 1 / (△f ref *N f,ref ) and △f ref = 15*10 3 Hz, and N f,ref =2048. T c Wow T f is a constant κ = T c / T f = 64 relationship. A frame consists of 10 subframes, and the duration of a single subframe is T. sf is 1ms. Subframes are further divided into slots, and the number of slots in a subframe depends on the subcarrier spacing. Each slot is divided into N slots based on a cyclic prefix (CP). slot symb It can be composed of symbols. For example, in some scenarios, in the case of normal CP, each slot consists of 14 OFDM symbols, and in the case of extended CP, each slot consists of 12 OFDM symbols. The numerology is exponentially scalable with subcarrier spacing △f = 2. u *Depends on 15 kHz. The following table shows the subcarrier spacing for regular CP △f = 2. u *Number of OFDM symbols per slot at 15 kHz (N) slot symb ), number of slots per frame (N frame,u slot ) and the number of slots per subframe (N subframe,u slot ) is shown.

[0067]

[0068] The following table shows the subcarrier spacing for extended CP △f = 2. u*Indicates the number of OFDM symbols per slot, the number of slots per frame, and the number of slots per subframe at 15 kHz.

[0069]

[0070] For a subcarrier spacing setting u, slots are n in increasing order within a subframe. u s ∈ {0, ..., nsubframe,u slot - 1} and n in increasing order within the frame u s,f ∈ {0, ..., n frame,u slot - Numbered as 1}.

[0071] Hereinafter, implementations of the present specification are described by referring to the minimum unit of time for scheduling uplink, downlink, and sidelink transmissions as a slot. However, depending on the wireless communication system, the minimum unit of time for scheduling may be referred to by a different term. For example, in an LTE-based system, the minimum unit of time for scheduling transmissions is referred to as a subframe or a transmission time interval (TTI), whereas in an NR-based system, the minimum unit of time for scheduling is referred to as a slot.

[0072] Figure 4 illustrates a resource grid of slots. A slot is a multiple (e.g., N) in the time domain. slot symb ) contains symbols of each numeral (e.g., subcarrier spacing) and carrier, a common resource block (CRB)N indicated by higher layer signaling (e.g., radio resource control (RRC) signaling). start,u grid Starting from,N size,u grid,x *N RB scDog subcarriers and N subframe,u symb A resource grid of OFDM symbols is defined, where N size,u grid,x is the number of resource blocks (RBs) in the resource grid, and the subscript x is DL for downlink and UL for uplink. N RB sc is the number of subcarriers per RB, and in 3GPP-based wireless communication systems, N RB sc is typically 12. For a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL), there is one resource grid. The carrier bandwidth N for subcarrier spacing configuration u size,u grid is given to the UE by higher layer parameters (e.g., RRC parameters) from the network. Each element in the resource grid for antenna port p and subcarrier spacing configuration u is called a resource element (RE), and one complex-valued symbol can be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index l indicating the symbol position relative to a reference point in the time domain. RBs can be classified into common resource blocks (CRBs) and physical resource blocks (PRBs). CRBs are numbered upwards from 0 in the frequency domain for subcarrier spacing configuration u. The center of subcarrier 0 of CRB 0 for subcarrier spacing configuration u coincides with 'point A', which is a common reference point for resource block grids. PRBs for subcarrier spacing configuration u are defined in a bandwidth part (BWP), numbered from 0 to N. size,u BWP,i-1, where i is the number of the bandwidth part. Common resource block n u CRB and bandwidth part i within physical resource block n PRB The relationship between the two is as follows: n u PRB = n u CRB +N start,u BWP,i , here N start,u BWP,i is a common resource block (BRB) whose bandwidth part starts relative to CRB 0. A BWP comprises multiple contiguous RBs in the frequency domain. For example, a BWP may be a given numeral u within a BWP i on a given carrier. i A subset of contiguous CRBs defined for a carrier. A carrier may contain up to N (e.g., 5) BWPs. A UE may be configured to have one or more BWPs on a given component carrier. Data communication is performed through the activated BWPs, and only a predetermined number (e.g., 1) of BWPs configured for the UE may be activated on the carrier.

[0073] In a 3GPP-based system, a control resource set (CORESET), which is a set of time-frequency resources for which a UE can monitor PDCCH, may be defined and / or configured. One or more CORESETs may be configured for a UE. A CORESET consists of a set of physical resource blocks (PRBs) with a duration of one to three OFDM symbols. The PRBs constituting the CORESET and the CORESET duration may be provided to the UE via higher layer (e.g., RRC) signaling. Within the configured CORESET(s), a set of PDCCH candidates is monitored according to the corresponding search space sets. In this specification, monitoring imply decoding (aka blind decoding) each PDCCH candidate according to the monitored DCI formats. The master information block (MIB) on the PBCH provides the UE with parameters (e.g., CORESET#0 configuration) for monitoring the PDCCH for scheduling the PDSCH carrying the system information block 1 (SIB1). The PBCH may also indicate that there is no associated SIB1, in which case the UE may be instructed on other frequencies to search for the SSB associated with SIB1, as well as a frequency range in which it can assume that there is no SSB associated with SSB1. At least CORESET#0, which is the CORESET for scheduling SIB1, may be configured via the MIB or dedicated RRC signaling.

[0074] The set of PDCCH candidates monitored by the UE is defined in terms of PDCCH search space sets. The search space set may be a common search space (CSS) set or a UE-specific search space (USS) set. Each CORESET configuration is associated with one or more search space sets, and each search space set is associated with one CORESET configuration.

[0075] Figure 5 illustrates multi-beam operation in a 3GPP-based system.

[0076] 5G and subsequent 3GPP-based systems can utilize high ultra-high frequency bands, such as the millimeter wave frequency band (mmWave) above 6 GHz, to transmit data to multiple users while maintaining high data rates by utilizing a wide frequency band. However, the millimeter wave frequency band has frequency characteristics that show very rapid signal attenuation over distance due to the use of such a high frequency band. Therefore, when using a band of at least 6 GHz or higher, 3GPP-based systems use a narrow beam transmission technique that solves the problem of coverage reduction due to rapid propagation attenuation by concentrating energy in a specific direction rather than omnidirectional signal transmission to compensate for the rapid propagation attenuation characteristics. However, when providing service using only a single narrow beam, the service range of a single BS is limited, so the BS gathers multiple narrow beams to provide service as a wide beam.

[0077] Figure 6 illustrates an example of SS / PBCH blocks (SSBs) being transmitted on a cell.

[0078] In 3GPP-based systems, each SSB is associated with a beam. For example, during a half-frame, different SSBs can be transmitted in different spatial directions (using different beams spanning the cell's coverage area). The possible temporal positions of the SSBs within a half-frame are determined by the subcarrier spacing, and the periodicity of the half-frames in which the SSBs are transmitted is set by the network. Multiple SSBs can be transmitted within the frequency span of a carrier. Different indices of the SSBs transmitted / detected in a cell can correspond to different BS (wide) Tx beams. In 3GPP-based systems, multi-beam operation is based on beam switching / beam scanning, which transmits / receives signals while changing the beam direction over time. For example, assuming that a BS supports at most N transmit beams, beam sweeping can be performed to transmit a synchronous signal block (SSB) consisting of a PSS, an SSS, and a PBCH in each of at most N beam directions (see SSB beam sweeping in FIG. 5). A set of SSBs in a beam sweep is specifically referred to as an SS burst set or SS burst. The number of SSBs in an SS burst set represents the number of beams for the beam sweep. Multiple SSB patterns are defined depending on the frequency band and the subcarrier spacing (SCS). In this specification, an SSB pattern is also referred to as an SSB timing pattern. For a half-frame with SSBs, the first (OFDM) symbol indices s for candidate SSBs can be determined according to the SCS of the SSBs as follows, where index 0 corresponds to the first symbol of the first slot in the half-frame. In some scenarios, SSB patterns according to the following table can be used.

[0079]

[0080] In the table above, FR represents a frequency range, for example, FR1 may correspond to a frequency range of 410 MHz to 7125 MHz, and FR2 may correspond to a frequency range of 24250 MHz to 52600 MHz. As can be seen from the table above, the number of SSBs in an SSB burst set may vary depending on the frequency range and SCS. The number of candidate SSBs in a half frame is numbered from 0 to L' in ascending order of time. max -Can be indexed up to 1. L max Let L be the maximum number of SSB indices in a cell or the maximum number of SSBs transmitted in a half frame, and for operation without shared spectrum channel access, L' max = L max For operations with shared spectrum channel access, L' max Wow L max may be different. For example, for operation with shared spectrum channel access in FR1, L' max = For SSBs of 10 and 15 kHz SCS and L' max = For SSBs of 20 and 30 kHz SCS, L max = can be defined as 8.

[0081] SSB(s) are transmitted periodically from 5 ms to 160 ms. A UE making an initial connection to the network can assume a period of 20 ms (e.g., 2 frames). In other words, for an initial cell connection, the UE can assume that a half-frame with SSBs appears with a periodicity of 2 frames.

[0082] Referring back to Figure 5, the UE can measure the power of SSB(s) received from BS transmission (Tx) beams using a wide reception (Rx) beam and select its preferred beam. For example, the UE can select one SSB from among the detected / received SSBs. 3GPP-based systems specify a specific mapping between SSBs and random access channel (RACH) occasions to allow the network to know which beam the UE has selected. A RACH occasion is a time and frequency resource available for transmission of a RACH preamble. The network can provide the UE with information about how many SSBs can be mapped to a single RACH occasion and how many preamble indices can be mapped to a single SSB. For example, if the network configures the number of SSBs per RACH epoch as 1 / N, then one SSB is associated with N RACH epochs (where N is a positive integer), and if the network configures the number of SSBs per RACH epoch as N, then N preamble indices are mapped to a single SSB. The UE selects an SSB from among the SSBs detected / received by the UE on the cell, and selects a RACH epoch based on the selected SSB to transmit. The BS can detect the RACH epoch including the PRACH from the UE through BS Rx beam sweeping, thereby knowing which SSB among the SSBs transmitted on the cell the UE has selected. The BS can determine a BS Tx beam for communication with the UE based on the SSB selected by the UE.

[0083] For finer beam tuning, CSI-RS may be transmitted. The BS may perform beam refinement using CSI-RS transmissions in narrower beams around the BS Tx beam determined based on the RACH timing at which the PRACH from the UE is detected (see CSI-RS beam sweeping in FIG. 5 ). The UE may measure the power of CSI-RSs received from these BS Tx narrow beams and report to the BS which of the BS Tx narrow beams it prefers. For example, the UE may measure CSI-RSs on CSI-RS resources to select at least one CSI-RS resource, and report to the BS a CSI-RS resource indicator (CRI) and a corresponding reference signal received power (RSRP) of the selected CSI-RS resource. The BS may determine a BS Tx narrow beam based on the CRI and / or corresponding RSRP reported by the UE, and repeatedly transmit CSI-RS through the BS Tx narrow beam (see P3 CSI-RS beam sweeping in FIG. 5) so that the UE performs Rx beam sweeping to find an appropriate UE Rx beam. The UE may measure the power of the CSI-RS received at each UE Rx beam to find an appropriate UE Rx beam.

[0084] A UE can detect a beam failure using CSI-RS / SSB. For example, if the L1-RSRP for a beam to be connected falls below a certain limit, the UE determines that the beam has failed and searches for other candidate beams with good quality. If a predetermined number of beam failures are detected, a beam failure recovery (BFR) procedure can be triggered using the candidate beam. The network can provide the UE with an identifier (ID) of an SSB transmitted by a cell, which is used to determine a candidate beam for BFR, and a preamble index used when performing BRF when selecting the candidate beam identified by the SSB. If the UE detects a predetermined number of beam failures, the network sends a BRF request to the network by transmitting a PRACH associated with the SSB ID, and the network provides a random access response (RAR) to the UE in response to the BRF request.

[0085] When receiving a PDSCH, the UE can assume that the DM-RS port of the PDSCH is quasi-co-located (QCL) with the associated SSB in terms of Doppler shift, Doppler spread, average delay, delay spread, and spatial Rx parameters. A transmission configuration indicator (TCI) state can be configured / indicated for the PDCCH / PDSCH. The TCI state can include quasi-co-location (QCL) information. For example, the UE can be configured with M TCI-state configurations provided by the BS via higher layer parameters to be able to decode the PDSCH according to a detected PDCCH with DCI for the UE and a given serving cell. Each TCI state includes parameters that configure a QCL relationship between one or two downlink reference signals (DL RSs) and DM-RS ports of a PDSCH, DM-RS ports of a PDCCH, or CSI-RS port(s) of a CSI-RS resource. The QCL relationship is configured by a higher layer parameter qcl-type1 for a first DL RS and a higher layer parameter qcl-type2 for a second DL RS (if configured). The QCL types corresponding to each DL RS are given by a higher layer parameter qcl-type in QCL-Info and can take one of the following values:

[0086] - 'typeA': {Doppler shift, Doppler spread, average delay, delay spread}

[0087] - 'typeB' : {Doppler shift, Doppler spread}

[0088] - 'typeC' : {Doppler shift, average delay}

[0089] - 'typeD' : {Spatial Rx parameter}

[0090] Figure 7 illustrates a non-terrestrial network (NTN) structure.

[0091] Recently, discussions are underway to enable 3GPP-based systems to support non-terrestrial networks (NTNs). NTNs are any network that includes non-terrestrial flying objects. If wireless communication via NTNs is enabled in 3GPP-based systems, the continuity of wireless communication services can be guaranteed, the reliability of wireless communication services can be enhanced through connectivity between various access technologies, and network resilience and reliability against disasters can be improved. For convenience of explanation, the following terminology will be used below.

[0092] - NTN: A radio access network consisting of BSs that provides non-terrestrial radio access to UEs using NTN payloads and NTN gateways mounted on airborne or space-borne NTN vehicles.

[0093] - NTN Gateway: An earth station located on the surface of the Earth that provides connectivity to NTN payloads using feeder links. An NTN Gateway is a transport network layer (TNL) node.

[0094] - NTN Payload: A network node mounted on a satellite or high altitude platform station that provides connectivity between service links and feeder links.

[0095] - Service Link: Wireless link between NTN payload and UE.

[0096] - Feeder link: A wireless link between the NTN gateway and the NTN payload.

[0097] - Satellite: A space-borne vehicle orbiting the Earth carrying an NTN payload.

[0098] - NTN cell: A cell that provides a service link between the UE and the NTN payload.

[0099] Referring to Figure 7, an NTN gateway is connected to an NTN payload mounted on a satellite or a high altitude platform system (HAPS) via a feeder link. The NTN payload is connected to a UE via a service link. The NTN gateway can be connected to the core network of a 3GPP-based system.

[0100] The NTN payload transmits a wireless protocol received from a UE (via a service link) to an NTN gateway (via a feeder link), and transmits a wireless protocol received from the NTN gateway (via a feeder link) to the UE (via a feeder link). An NTN gateway can service multiple NTN payloads, and an NTN payload can be serviced by multiple NTN gateways. For NTN, a tracking area can correspond to a fixed geographical area, and each mapping can be configured in the radio access network.

[0101] The following three time service links are supported:

[0102] - Earth-fixed service link: A service link that is provisioned by beam(s) that continuously cover the same geographic areas (e.g., in the case of GSO satellites).

[0103] - Quasi-Earth-fixed service link: A service link supplied by beam(s) that cover one geographic area for a limited period and another geographic area for another period (e.g., in the case of NGSOs that produce steerable beams).

[0104] - Earth-moving service link: A service link whose coverage area is supplied by beam(s) that glide over the Earth's surface (e.g., for NGSO satellites that produce fixed or non-steerable beams).

[0105] NTN can include satellite communication networks, air-to-ground networks, and UAV networks. One of the key concepts in NTN is that NTN cells are provided by non-geostationary orbit (NGSO) satellites that periodically orbit the Earth. Each satellite has its own orbit, which is included in the satellite position estimate information. Based on the satellite position estimate information, the network can predict feeder link switchover and manage UE mobility and radio resource control. A BS providing NTN access can broadcast orbital trajectory information or ephemeris information regarding coordinates for the NTN payload. EphemerisInfo can provide satellite position estimates in the form of position and velocity state vectors or in the form of orbital parameters. The following tables illustrate the EphemerisInfo information elements broadcast by the BS and describe the fields of the EphemerisInfo IE.

[0106]

[0107]

[0108] Satellite communication networks may include low Earth orbit (LEO) satellites, medium Earth orbit (MEO) satellites, and geosynchronous Earth orbit (GEO) satellites.

[0109]

[0110] The following are examples of NTN deployment scenarios.

[0111]

[0112] Figure 8 illustrates a synchronous raster and a channel raster used in some implementations.

[0113] A UE attempting to access a network performs cell search, which is a process for the UE to acquire time and frequency synchronization with a cell and to detect the physical layer cell identity (PCI) of the cell. During the cell search operations performed when the UE is powered on, the UE acquires the necessary information required to access the cell using SSB. The UE performing the cell search attempts to detect SSB while moving in the frequency domain, assuming a synchronization raster. The synchronization raster represents the possible frequency locations of SSB that can be used by the UE to acquire system information when there is no explicit signaling of the SSB location. In LTE, the frequency domain locations of PSS / SSS are always fixed around the carrier center frequency (see Figure 8(a)). In contrast, in NR, a set of possible frequency locations for SSB is defined based on the frequency band, called the synchronization raster, and the UE needs to search for SSB based on the synchronization raster. Unlike LTE, where the UE searches for PSS / SSS at all carrier raster locations, in NR, a sparser synchronization raster is defined for the UE (see Figure 8(b)). Therefore, in NR, the UE only needs to search for SSB at a sparser synchronization raster than in LTE. The carrier raster is also called a channel raster, which represents possible carrier locations. The global frequency channel raster is a set of radio frequency (RF) frequencies F REFDefines a set of RF reference frequencies. RF reference frequencies are used in signaling to identify the location of RF channels, SSB blocks, and other elements. A global frequency raster is used to define all frequencies from 0 to 100 GHz. In NR, RF reference frequencies are expressed in units of NR absolute radio frequency channel number (NR-ARFCN) and the RF reference frequency F in MHz. REF can be given by the following equation: F REF = F REF-Offs + △F Global (N REF - N REF-Offs ), where △F Global is the granularity of the frequency raster, and N REF is NR-ARFCN, and F REF-Offs and N REF-Offs can be given by the following table.

[0114]

[0115] A channel raster defines a subset of RF reference frequencies that can be used to identify RF channel locations in the uplink and downlink.

[0116] A global synchronization raster is defined for all frequencies, and the frequency location of the SSB is determined by the SS with the corresponding number global synchronization signal number (GSCN). REF is defined as the SS for all frequency ranges REF The parameters defining GSCN are defined, for example, in the following table.

[0117]

[0118] The synchronization raster for each band can be given, for example, by the following table. The distance between applicable GSCN entries is indicated in the following table.<Step size> can be given by

[0119]

[0120] The notes shown in Table 10 can be explained by the following table.

[0121]

[0122] Referring to Table 9 and Table 10, for n35, the UE can perform cell search by incrementing GSCN by 1 starting from GSCN = 6125.

[0123] Cell selection is performed based on cell-defining SSBs (CD-SSBs) where the synchronization raster is located. If an SSB is associated with remaining minimum system information (RMSI) (e.g., SIB1), for example, if the MIB carried by the PBCH within the SSB includes parameters for transmission of the PDCCH that schedules the RMSI, the SSB is called a CD-SSB. The UE can search the frequency bands and identify the strongest cell based on the SSB for each carrier frequency, and select the cell on which to perform the initial connection.

[0124] SSB related operations

[0125] Figure 9 illustrates the SSB structure. Based on SSB, a terminal can perform cell search, system information acquisition, beam alignment for initial access, and DL measurements. SSB is used interchangeably with the SS / PBCH (Synchronization Signal / Physical Broadcast channel) block.

[0126] Referring to Figure 9, SSB is composed of PSS, SSS, and PBCH. SSB is composed of four consecutive OFDM symbols, and PSS, PBCH, SSS / PBCH, and PBCH are transmitted for each OFDM symbol. PSS and SSS are each composed of one OFDM symbol and 127 subcarriers, and PBCH is composed of three OFDM symbols and 576 subcarriers. Polar coding and QPSK (Quadrature Phase Shift Keying) are applied to PBCH. PBCH is composed of data RE and DMRS (Demodulation Reference Signal) RE for each OFDM symbol. There are three DMRS REs for each RB, and three data REs exist between DMRS REs.

[0127] Cell search refers to the process by which a terminal acquires time / frequency synchronization of a cell and detects the cell ID (Identifier) ​​(e.g., Physical layer Cell ID, PCID) of the cell. The PSS is used to detect a cell ID within a cell ID group, and the SSS is used to detect a cell ID group. The PBCH is used for SSB (time) index detection and half-frame detection.

[0128] The cell search process of the terminal can be summarized as shown in Table 12 below.

[0129] Type behaviors of signals 1 st stepPSS* SS / PBCH block (SSB) symbol timing acquisition* Cell ID detection within cell ID group (3 hypothesis)2 nd StepSSS* Cell ID group detection (336 hypothesis)3 rd StepPBCH DMRS* SSB index and half-frame (HF) index (slot and frame boundary detection)4 thStepPBCH* Timing information (80ms, System Frame Number (SFN), SSB Index, HF)* Minimum Remaining System Information (RMSI) Control Resource Set (CORESET) / Search Space Configuration5 th StepPDCCH and PDSCH* Cell Access Information * RACH Configuration

[0130] There are 336 cell ID groups, and 3 cell IDs exist for each cell ID group. There are a total of 1008 cell IDs. Information about the cell ID group to which the cell ID of a cell belongs is provided / obtained through the SSS of the cell, and information about the cell ID among the 336 cells within the cell ID is provided / obtained through the PSS.

[0131] Figure 10 illustrates a situation where a terrestrial network (TN) and a non-terrestrial network (NTN) coexist.

[0132] Referring to Fig. 10, if the UE is served by the BS of the TN, the UE reception (RX) beam will be directed toward the ground, and if the UE is served by the BS of the NTN, the UE RX beam will be directed toward the sky. For frequency bands where NTN and TN can coexist, the UE does not have any prior information about the BS types during the initial attachment. In this case, since the UE does not know during the initial attachment whether its RX beam for SSB reception should be formed toward the TN-BS or the NTN-BS, the UE will randomly select the RX beam direction. If the randomly selected RX beam direction is not appropriate, cell search will take more time, which may result in performance degradation. Therefore, NTN / TN differentiation technology is required for NTN and TN coexistence. Hereinafter, a method for performing cell search and / or connection based on the priorities between NTN and TN as the NTN / TN differentiation technology is described in detail.

[0133] Priority-based NTN / TN cell search

[0134] The UE can detect / search for SSBs based on a synchronization raster to perform cell search for cell selection (or reselection). The UE can measure the power of the detected SSB, select a specific SSB among the detected SSBs based on the measured power, and perform an initial access procedure for cell access based on the specific SSB.

[0135] Meanwhile, the terminal may perform cell search for an operating band where NTN and TN coexist, as described above. In this case, the terminal may be unclear as to which cell among the NTN cell and the TN cell should be used for SSB detection during the cell search.

[0136] Hereinafter, for convenience of explanation, the cell for the NTN is defined as an NTN cell, the cell for the TN is defined as a TN cell, and either the cell for the NTN or the cell for the TN is defined as a network cell. Furthermore, with respect to cell search based on priority, it is explained assuming that the priority is applied to perform cell search between the TN cell and the NTN cell in the same synchronous raster, even if there is no separate definition.

[0137] FIG. 11 and FIG. 12 are diagrams for explaining how a terminal attempts to detect SSB based on priority.

[0138] As described above, the terminal may attempt to detect an SSB for cell selection / search for a frequency band (or, a first frequency band) in which an NTN cell and a TN cell coexist. At this time, the terminal may perform cell selection / search for the NTN cell and the TN cell based on priorities. Here, the priorities between the TN cell and the NTN cell may be preset / defined. The terminal may perform cell search from a cell with a higher priority to a cell with a lower priority among the TN cell and the NTN cell based on the priorities. For example, if the TN cell is set as a network cell with a higher priority than the NTN cell, the terminal may attempt to detect an SSB for the TN cell before attempting to detect an SSB for the NTN cell.

[0139] Hereinafter, a case in which detection of the SSB is attempted when the priority of the TN cell is higher than that of the NTN cell will be described in detail with reference to FIG. 11, and a case in which detection of the SSB is attempted when the priority of the NTN cell is higher than that of the TN cell will be described in detail with reference to FIG. 12.

[0140] Referring to FIG. 11, the terminal may attempt to detect an SSB that is expected / assumed to be associated with the TN cell, which is a high-priority network cell (S111). For example, the terminal may attempt to detect an SSB using reception beams beamformed in the terrestrial direction (where the TN cell may be located), thereby giving priority to the detection of an SSB for the TN cell over the NTN cell.

[0141] Next, the terminal can terminate cell search based on detection of the SSB if an SSB for the TN cell is detected (S113, Yes). In this case, the terminal can obtain time and frequency synchronization for the TN cell based on the SSB and perform an initial access procedure for the TN cell.

[0142] Meanwhile, the terminal can obtain a PBCH including a Master Information Block (MIB) from the detected SSB, and can confirm or identify whether the SSB is for a TN cell or an NTN cell based on the information about the cell obtained from the Master Information Block (MIB).

[0143] Alternatively, the terminal may (re)attempt to detect an SSB (S115) which may be assumed / expected to be for a low priority NTN cell if an SSB for the high priority TN cell is not detected (S113, No). For example, the terminal may re-attempt to detect an SSB for the low priority NTN cell if the detection of the SSB for the TN cell fails. For example, if the detection of an SSB using the receive beams beamformed in the ground direction (where the TN cell may be located) fails, the terminal may (re)attempt to detect the SSB by changing the direction of the receive beams toward the sky (where the NTN cells may be located) in order to perform a cell search for the NTN cell.

[0144] For example, the terminal may attempt to detect an SSB for a high-priority TN cell for a given synch raster k. If the detection of an SSB for the TN cell for the synch raster k fails, the terminal may re-attempt to detect an SSB for the NTN cell for the synch raster k for which the detection of the SSB for the TN cell failed.

[0145] If the terminal succeeds in detecting an SSB for the TN cell, the terminal may perform an initial access procedure for the TN cell based on the successfully detected SSB. Alternatively, if the terminal fails to detect an SSB for the TN cell and attempts to detect an SSB for the NTN cell, the terminal may perform an initial access procedure for the NTN cell if the detection of an SSB for the NTN cell succeeds.

[0146] Referring to FIG. 12, the terminal may attempt to detect an SSB that is expected / assumed to be related to the NTN cell, which is a high-priority network, as a priority (S121). For example, the terminal may attempt to detect an SSB using reception beams beamformed toward the sky (where NTN cells may be located) in order to prioritize cell search for the NTN cell. The terminal may perform cell search for the NTN cell as a priority by using reception beams toward the sky.

[0147] Next, the terminal can terminate the cell search if an SSB for the NTN cell is detected (S123, Yes). In this case, the UE can obtain time and frequency synchronization for the NTN cell based on the SSB and perform an initial access procedure for the NTN cell.

[0148] Alternatively, if an SSB for the high-priority NTN cell is not detected (S123, No), the UE may (re)attempt to detect an SSB (S125) that may be assumed / expected to be for a low-priority TN cell. For example, if the detection of an SSB for the NTN cell fails, the UE may re-attempt to detect the SSB for the low-priority TN cell. For example, if the detection of an SSB using the skyward beamformed receive beams (where the NTN cell may be located) fails, the UE may change the receive beam to the groundward beamformed receive beams and re-attempt to detect the SSB. If an SSB is detected using the groundward beamformed receive beams, the UE may assume / expect the detected SSB to be an SSB for the TN cell.

[0149] For example, the terminal may attempt to detect an SSB for a high-priority NTN cell for a given synch raster k. If the detection of an SSB for the NTN cell for the synch raster k fails, the terminal may re-attempt to detect an SSB for the TN cell for the synch raster k for which the detection of the SSB for the NTN cell failed.

[0150] Below, a method for setting / determining priorities between the TN cell and the NTN cell is described in detail.

[0151] FIG. 13 is a diagram for explaining a method for setting / determining priorities between the TN cell and the NTN cell.

[0152] The priority between the above-described TN cell and the NTN cell can be determined / set based on at least one of the following Alt 1-1, Alt 1-2, Alt 1-3, and Alt 1-4.

[0153] (1) Alt 1-1

[0154] The above priority may be set so that the TN cell always has priority over the NTN cell. In this case, the terminal may always perform detection of an SSB for the TN cell with priority, and if an SSB for the TN cell is detected, the terminal may perform an initial access procedure based on the detected SSB. Alternatively, if detection of an SSB for the TN cell fails, the terminal may (re)attempt detection of an SSB for the NTN cell.

[0155] (2) Alt 1-2

[0156] The above priority may be set so that the NTN cell always has priority over the TN cell. In this case, the terminal may always perform detection of an SSB for the NTN cell with priority, and if an SSB for the NTN cell is detected, the terminal may perform an initial access procedure for the NTN cell based on the detected SSB. Alternatively, if detection of an SSB for the NTN cell fails, the terminal may (re)attempt detection of an SSB for the TN cell.

[0157] (2) Alt 1-3

[0158] The above priorities may be set / determined based on the various terminal types (or communication types), applications and / or requirements.

[0159] For example, as illustrated in FIG. 13, the terminal may support an LPWA (Low Power Wide Area) or RedCAP (Reduced Capability) type in which power (transmission / reception power) is limited, an URLLC (ultra-reliable low-latency communications) type requiring sensitive delay requirements, an mMTC (Massive Machine Type Communications) or IoT (Internet of things) (or NarrowBand-IoT) type requiring massive connectivity, and / or a V2X (Vehicle-to-Everything) type having high mobility (e.g., communication between vehicles capable of traveling at high speeds, communication within a train). In this case, the network (or the terminal itself) may set / determine priorities between the NTN and the TN based on each type, requirements of each type, applications, etc.

[0160] For example, for a terminal of a power-constrained terminal type or communication type, such as LPWA or RedCap, the priority may be determined / set such that the TN cell has priority over the NTN cell. Alternatively, for a terminal of a URLLC terminal type or communication type, which requires sensitive delay requirements, the priority may be determined / set such that the TN cell has priority over the NTN cell.

[0161] Alternatively, for the terminals of the mMTC or IoT type requiring massive connectivity, the priority may be determined / set such that the NTN cell has priority over the TN cell. Alternatively, for the terminals of the V2X type having high mobility, the priority may be determined / set such that the NTN cell has priority over the TN cell.

[0162] (4) Alt 1-4

[0163] Alternatively, the terminal may directly determine / set the priority between the NTN cell and the TN cell based on the surrounding environment or the surrounding communication environment. For example, the terminal may set / determine the priority so that the TN cell has priority over the NTN cell when the surrounding environment or the surrounding communication environment is an urban environment. Alternatively, the terminal may set / determine the priority so that the NTN cell has priority over the TN cell when the surrounding environment or the surrounding communication environment is a rural environment. For example, the terminal may determine whether its location is an urban environment or a rural environment through GPS, etc.

[0164] Alternatively, the terminal may set the priority so that the NTN cell has priority over the TN cell if it is determined to be located on a highway based on GPS / zone ID / movement speed, etc. Alternatively, the terminal may set the priority so that the NTN cell has priority over the TN cell if its movement speed is above a certain threshold.

[0165] Figures 14 to 16 are diagrams for explaining a method for the terminal to perform cell search in a frequency band where NTN cells and TN cells coexist.

[0166] The terminal may give priority to detection of an SSB for a network cell with a higher priority among NTN cells and TN cells for a synchronization raster. The terminal may determine whether to additionally attempt detection of an SSB for a network cell with a lower priority in the synchronization raster in which detection of an SSB for a network cell with a higher priority has been attempted. Specifically, the terminal may additionally attempt detection of an SSB for a network cell with a lower priority for the synchronization raster if detection of an SSB for the network cell with a higher priority fails (Alt 2-1). Alternatively, the terminal may determine whether to (re)attempt detection of an SSB for a cell with a lower priority based on information included in an SSB detected for the network cell with a higher priority (Alt 2-3).

[0167] Alternatively, if both the high-priority network cell and the SSB for the high-priority network cell are detected for the synchronization raster, the terminal may select / determine a network cell to perform an initial access procedure among the two network cells based on a quality difference between the two detected SSBs (Alt 2-2).

[0168] The above-described Alt 2-1 is described in detail with reference to Fig. 14, Alt 2-2 with reference to Fig. 15, and Alt 2-3 with reference to Fig. 16.

[0169] (1) Alt 2-1 (Priority-only)

[0170] Alt 2-1 allows the terminal to perform a cell search procedure for the frequency band where the TN cell and the NTN cell coexist, considering only the priorities. For example, the terminal may attempt to detect an SSB for cell search, considering only the priorities for the TN cell and the NTN cell, and perform an initial access procedure for the detected SSB.

[0171] Referring to FIG. 14, the terminal may attempt to detect an SSB for a network cell with the higher priority among the NTN cell and the TN cell (S141). For example, the terminal may attempt to detect an SSB for the network cell with the higher priority among the NTN cell and the TN cell in synchronization raster k. If the terminal successfully detects an SSB for the network cell with the higher priority in synchronization raster k (S143, Yes), the terminal may not (re)attempt to detect an SSB for the network cell with the lower priority in synchronization raster k. For example, if the TN cell has a higher priority among the NTN cell and the TN cell, the terminal may give priority to detecting an SSB for the TN cell in synchronization raster k, and if the detection of the SSB is successful, the terminal may not (re)attempt to detect an SSB for the NTN cell in synchronization raster k.

[0172] Alternatively, if the SSB for the high-priority network cell is not detected in the synchronization raster k (S143, No), the terminal may (re)attempt to detect the SSB for the low-priority network cell in the synchronization raster k (S145). For example, if the TN cell has a high priority among the NTN cell and the TN cell, the terminal may perform detection of the SSB for the TN cell with priority in the synchronization raster k, and if the SSB for the TN cell is not detected in the synchronization raster k, (re)attempt to detect the SSB for the NTN cell in the synchronization raster. For example, the terminal may detect the SSB for the TN cell with priority using ground-facing reception beams in the synchronization raster k, and if detection of the SSB for the TN cell fails, (re)attempt to detect the SSB for the NTN cell in the synchronization raster k using sky-facing reception beams.

[0173] Alternatively, if the terminal fails to detect SSB for both the high priority network and the low priority network in the synchronization raster k (i.e., fails to detect SSB for both the NTN cell and the TN cell), the terminal may retry detecting the SSB based on the priorities as described above in the next synchronization raster, synchronization raster k+1.

[0174] Next, the terminal can perform an initial access procedure based on the detected SSB (S147). For example, if the high-priority network cell is a TN cell and an SSB for the TN cell is detected within the synchronization raster k, the terminal can perform an initial access procedure for the TN cell based on the SSB detected for the TN cell. Alternatively, if the terminal (re)attempts to detect an SSB for the NTN cell because an SSB for the TN cell is not detected within the synchronization raster k, and an SSB for the NTN cell is detected within the synchronization raster k, the terminal can perform the initial access procedure based on the SSB detected for the NTN cell.

[0175] For example, the terminal may set a higher priority for the TN cell among the NTN cell and the TN cell. In this case, the terminal may first attempt to detect an SSB for the TN cell with the higher priority in the synchronization raster k. If the terminal successfully detects an SSB for the TN cell with the higher priority in the synchronization raster k, the terminal may perform an initial access procedure for the TN cell based on the detected SSB. Meanwhile, if the terminal successfully detects an SSB for the TN cell, the terminal may not (re)attempt to detect an SSB for the NTN cell in the synchronization raster k.

[0176] (2) Alt 2-2 (Priority + RSRP threshold)

[0177] Alt 2-2 is a method for performing the cell search procedure based on the above priorities, and when SSBs are detected for both the NTN cell and the TN cell, the terminal selects a cell on which to perform an initial access procedure among the NTN cell and the TN cell based on the quality of the detected SSB and a second threshold value.

[0178] Meanwhile, for the convenience of explanation, in the following description, the SSB for the network cell with a high priority among the NTN cell and the TN cell is defined as the first SSB, and the SSB for the network cell with a low priority is defined as the second SSB.

[0179] Referring to FIG. 15, the terminal may sequentially attempt to detect SSBs for the NTN cell and the TN cell in synchronization raster k based on the priorities (S151). That is, the terminal may attempt to detect the SSBs in the order of network cells with higher priorities to network cells with lower priorities for synchronization raster k. For example, if the TN cell has a higher priority than the NTN cell, the terminal may first attempt to detect the SSB (first SSB) for the TN cell (using depth beams in the ground direction) in synchronization raster k and then (re)attempt to detect the SSB (second SSB) for the NTN cell.

[0180] For example, the terminal may attempt to detect a first SSB, which is an SSB for a high-priority network cell, for the synchronization raster k, as a priority, and, if the first SSB is detected, may (re)attempt to detect a second SSB, which is an SSB for a low-priority network cell. At this time, the terminal may detect both the first SSB and the second SSB for the synchronization raster k. In other words, the terminal may detect not only the SSB for the high-priority network cell but also the SSB for the low-priority network cell for the synchronization raster.

[0181] Next, if both the first SSB and the second SSB are detected for one synchronization raster (S153, Yes), the terminal may select a cell for performing the initial access procedure among the high-priority network cell and the low-priority network cell based on the difference in quality between the first SSB and the second SSB and the first threshold (S155). Meanwhile, the first threshold may be preset through a network or other upper layer signal, a physical layer signal, etc.

[0182] Specifically, if the quality of the second SSB is higher than (or exceeds) the quality of the first SSB by the first threshold, the terminal may select a network cell with the lower priority as a cell for performing the initial access procedure even if the network cell has the lower priority. Conversely, if the quality of the second SSB is not higher than the quality of the first SSB by the threshold, the terminal may select a network cell with the higher priority as a cell for performing the initial access procedure according to the priorities. Next, the terminal may perform an initial access procedure for the selected network cell (S157).

[0183] Here, the quality of the SSB may be the RSRP (Reference Signals Received Power) measured in the detection of the SSB, and the first threshold may be preset / indicated as a threshold value for the RSRP. For example, both the first SSB and the second SSB may be detected within the synchronization raster k. In this case, the terminal may determine the quality (RSRP) of the second SSB. low ) in the quality of the first SSB (RSRP) high ) is the value minus the first critical value ( ) or more (or exceeds) (RSRP low - RSRP high > ) may select a network cell with a lower priority as a cell for the initial access procedure. Alternatively, the terminal may select a quality (RSRP) for the second SSB low ) for the first SSB above (RSRP) high ) is the value minus the first critical value ( ) less than (RSRP low - RSRP high < ) in which case, the network cell with the higher priority can be selected as the cell for the initial access procedure.

[0184] For example, if the TN cell has a higher priority than the NTN cell, and both the first SSB for the TN cell and the second SSB for the NTN cell are detected for one synchronization raster, the terminal may select a cell (or network cell) for the initial access procedure based on the difference between the quality of the first SSB and the quality of the second SSB and the first threshold. The quality (RSRP) for the second SSB low ) for the first SSB above (RSRP) high ) is the value minus the first critical value ( ) or more (or exceeds) (RSRP low - RSRP high > ), the terminal may select the NTN cell as a cell for performing the initial access procedure, and perform the initial access procedure for the NTN cell based on the second SSB. Alternatively, the quality (RSRP) for the second SSB low ) for the first SSB above (RSRP) high ) is the value minus the first critical value ( ) is less than (or below) (RSRP low - RSRP high < ), the terminal may select the TN cell as a cell for performing the initial access procedure, and perform the initial access procedure for the TN cell based on the first SSB.

[0185] Alternatively, the terminal may succeed in detecting only one of the SSB for the TN cell and the SSB for the NTN cell in the sequential detection of SSBs for the TN cell and the NTN cell according to the priorities (S153, No). For example, the terminal may fail to detect the first SSB for the high-priority network cell in the synchronization raster k and succeed in detecting the second SSB for the low-priority network cell. Alternatively, the terminal may fail to detect the second SSB after successfully detecting the first SSB in the synchronization raster k. In this case, the terminal may perform an initial access procedure based on the SSB for the detected one network cell (S157). For example, if only the first SSB for the TN cell, which is the high-priority network cell, is detected, the terminal may perform an initial access procedure for the TN cell based on the first SSB. In contrast, if only the detection of the second SSB is successful, the terminal can perform an initial access procedure for the NTN cell with a lower priority based on the second SSB.

[0186] Alternatively, the terminal may fail to detect SSB for both the high-priority network cell and the low-priority network cell within the synchronization raster k. In this case, the terminal may retry detecting SSB for the NTN cell and / or the TN cell based on priorities, as described above, for the synchronization raster k+1, which is the next synchronization raster of the synchronization raster k.

[0187] (3) Alt 2-3 (Priority + indication)

[0188] Alt 2-3 may attempt to detect SSB for a network cell with a higher priority among the NTN cell and the TN cell according to the above priorities, and may determine whether to (re)attempt detection of SSB for a network cell with a lower priority based on information included in the detected SSB.

[0189] Referring to FIG. 16, the terminal can detect the first SSB for the high-priority network cell in the synchronization raster (S161). For example, if the TN cell has the high priority, the terminal can detect the first SSB for the TN cell using ground-facing reception beams in the synchronization raster.

[0190] When the first SSB is detected, the terminal provides indication information and / or a second threshold (RSRP) indicating the presence of the network cell with the lower priority from the detected first SSB. th ) can obtain information about the detected first SSB. For example, the terminal can obtain a PBCH from the detected first SSB, and can obtain the indication information and the second threshold from a MIB (Master Information Block) included in the PBCH. In addition, the terminal can confirm or identify whether the first SSB is for a TN cell or an NTN cell based on information about a cell associated with the detected first SSB from the MIB. For example, when the TN cell has the high priority, the terminal can obtain the indication information about the presence or absence of the NTN cell from the first SSB.

[0191] Next, the terminal may determine whether it is necessary to (re)attempt detection of a second SSB for the lower priority network cell in the synchronization raster in which the first SSB was detected based on the indication information included in the first SSB and the second threshold value (S163).

[0192] Specifically, the terminal indicates that the indication information included in the first SSB indicates the presence of the low-priority network cell, and the quality of the first SSB is equal to the threshold value (RSRP th ) is less than (or below), the terminal may (re)attempt to detect the SSB for the synchronization raster k in order to detect the second SSB for the lower priority network cell.

[0193] In contrast, the quality of the first SSB is higher than the threshold (RSRP th ) or more (or exceeds), the terminal may not attempt to detect the second SSB for the low-priority network cell in the synchronization raster k even if the indication information indicates the presence of the low-priority network cell.

[0194] If it is decided to attempt detection of a second SSB for the low-priority network cell and detection of the second SSB is successful, the terminal may determine whether to perform the initial access procedure based on either the first SSB or the second SSB (S165). For example, the terminal may perform the initial access procedure for the low-priority network cell based on the second SSB if the quality of the second SSB is equal to or higher than the second threshold. Alternatively, as in Alt 2-2 described above, if the quality of the second SSB is equal to or higher than the first threshold compared to the first SSB, the terminal may perform the initial access procedure for the low-priority network cell rather than the high-priority network cell.

[0195] Alternatively, if the quality of the second SSB is lower than the second threshold, the terminal may perform an initial access procedure for a network cell with a higher priority according to the priority. Alternatively, if the quality of both the first SSB and the second SSB is lower than the second threshold, the terminal may not perform the initial access procedure and may retry detecting the first SSB and / or the second SSB at synchronization raster k+1.

[0196] For example, the TN cell may have a higher priority than the NTN cell. In this case, the terminal may preferentially attempt to detect the first SSB for the TN cell on the synchronization raster k. In other words, the terminal may preferentially attempt to detect the first SSB for the TN cell by attempting to detect the SSB using the ground-facing reception beams on the synchronization raster k. When the terminal detects the first SSB, the terminal may determine whether to additionally attempt to detect the second SSB for the NTN cell on the synchronization raster k based on the indication information included in the SSB and the second threshold value. When the indication information indicates the presence of an NTN cell and the quality of the first SSB is less than (or equal to or lower than) the second threshold value, the terminal may additionally attempt to detect the second SSB for the NTN cell on the synchronization raster k. For example, the terminal may (re)attempt detection of a second SSB for the NTN cell by detecting an SSB using the skyward receiving beams in the synchronization raster k. Next, if the second SSB, whose quality is measured to be equal to or greater than (or exceeding) the second threshold, is detected, the terminal may perform an initial access procedure for the NTN cell based on the second SSB. Alternatively, if the quality of the second SSB is less than (or equal to or less than) the second threshold, the terminal may perform an initial access procedure for the TN cell based on the first SSB in accordance with the priority. Alternatively, the terminal may not perform an initial access procedure based on an SSB detected in the synchronization raster k based on the quality of the first SSB and the second SSB being less than the second threshold, and may sequentially attempt detection of an SSB for the NTN cell in the TN cell in accordance with the priority in the next synchronization raster, synchronization raster k+1.

[0197] Alternatively, if the first SSB is not detected in the synchronization raster k, the terminal may attempt to detect the first SSB in the next synchronization raster k+1. For example, Alt 2-3 differs from Alt 2-1 and / or Alt 2-2 in that it does not attempt to detect an additional SSB for a lower priority network cell if detection of the first SSB for the higher priority network cell for the synchronization raster fails.

[0198] In this way, in a frequency band where the TN cell and the NTN cell coexist, the terminal can clearly determine which network cell to perform cell search for with priority according to the priority. That is, when the TN cell is given priority, the terminal can quickly and effectively search for the TN cell by using the reception beams for the ground direction. Alternatively, when the NTN cell is given priority, the terminal can quickly and effectively search for the NTN cell by using the reception beams for the sky direction. Furthermore, based on the indication information, the terminal can easily identify the coexistence of NTN cells and TN cells in the frequency band, and can clearly determine whether cell search for a network cell with a lower priority is necessary based on the second threshold. Furthermore, when SSBs for both the TN cell and the NTN cell are detected, the terminal can clearly and effectively determine whether to perform an initial access procedure for a cell for which network based on a preset first threshold.

[0199] In some implementations of the present disclosure, transmitting a signal / channel by a UE or BS through a transmit beam may be expressed as transmitting the signal / channel through a spatial domain transmit filter. In some implementations of the present disclosure, receiving a signal / channel by a UE or BS through a receive beam may also be expressed as receiving the signal / channel using a spatial domain receive filter. For example, transmitting using the same transmit beam may mean transmitting using the same spatial domain transmit filter, and receiving using the same receive beam may mean receiving using the same spatial domain receive filter.

[0200] Here, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification may include not only LTE, NR, and 6G, but also Narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology, and may be implemented with standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification may perform communication based on LTE-M technology. At this time, for example, LTE-M technology may be an example of LPWAN technology, and may be called by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology can be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification can include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create PAN (personal area networks) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

[0201] The embodiments described above are combinations of components and features of the present invention in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to form an embodiment of the present invention by combining some components and / or features. The order of operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is self-evident that claims that do not have an explicit citation relationship in the patent claims may be combined to form an embodiment or may be incorporated as a new claim through a post-application amendment.

[0202] In this document, embodiments of the present invention have been described primarily focusing on the signal transmission and reception relationship between a terminal and a base station. This transmission and reception relationship is equally / similarly extended to signal transmission and reception between a terminal and a relay or a base station and a relay. Certain operations described as being performed by a base station in this document may, in some cases, be performed by its upper node. That is, it is obvious that various operations performed for communication with a terminal in a network composed of multiple network nodes including a base station may be performed by the base station or other network nodes other than the base station. The base station may be replaced by terms such as fixed station, Node B, eNode B (eNB), and access point. In addition, the terminal may be replaced by terms such as UE (User Equipment), MS (Mobile Station), MSS (Mobile Subscriber Station).

[0203] Embodiments of the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[0204] When implemented via firmware or software, an embodiment of the present invention may be implemented in the form of modules, procedures, functions, etc. that perform the functions or operations described above. The software code may be stored in a memory unit and executed by a processor. The memory unit may be located within or outside the processor and may exchange data with the processor via various known means.

[0205] It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the scope of the invention. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present invention are intended to be included within the scope of the present invention.

[0206] The embodiments of the present invention as described above can be applied to various mobile communication systems.

Claims

1. In a method for a terminal to receive a downlink signal in a wireless communication system, A step of attempting to detect a synchronization signal block (SSB) on a first frequency band supported by a terrestrial network (TN) cell and a non-terrestrial network (NTN) cell; and A step of performing an initial access procedure based on the detected SSB is included, A method wherein the attempt to detect the SSB is performed with priority on a cell with a higher priority among the TN cell and the NTN cell based on the priorities set for the TN cell and the NTN cell.

2. In paragraph 1, Based on the TN cell having the higher priority, the detection attempt of the SSB is performed in the order of the TN cell to the NTN cell, A method characterized in that, based on the detection of both the first SSB for the TN cell and the second SSB for the NTN cell, the initial access procedure is performed for one cell determined among the TN cell and the NTN cell based on the first threshold set for the quality of the SSB and the priority.

3. In paragraph 2, A method characterized in that, based on the quality of the second SSB being higher than the quality of the first SSB by the first threshold, the one cell is determined to be the NTN cell even if the TN has a higher priority.

4. In paragraph 2, A method characterized in that the one cell is determined as the TN cell with the higher priority based on the quality of the first SSB not being lower than the quality of the second SSB by the first threshold.

5. In paragraph 1, A method characterized in that the terminal attempts to detect the SSB for the low-priority cell among the TN cell and the NTN cell, based on the detection of the SSB including indication information indicating the presence of the low-priority cell in the SSB and a second threshold, and the quality of the SSB being lower than the second threshold.

6. In paragraph 1, A method, characterized in that the above priority is set based on at least one of the type, mobility, communication environment and service requirements of the terminal.

7. In paragraph 6, A method characterized in that the NTN is set to a higher priority than the TN based on whether the type of the terminal is mMTC (massive Machine Type Communications) type, V2X (Vehicle to Everything) type, or NB-IoT (Narrowband Internet of things) type.

8. In a terminal receiving a downlink signal in a wireless communication system, At least one transmitter / receiver; at least one processor; and At least one computer memory operably connectable to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations; The above operations include an operation of attempting to detect a synchronization block (SSB) on a specific frequency band supporting a terrestrial network (TN) and a non-terrestrial network (NTN), and performing an initial access procedure based on the detected SSB. The attempt to detect the SSB is performed with priority on a cell with a higher priority among the TN cell and the NTN cell based on the priorities set for the TN cell and the NTN cell.

9. In a processing device for receiving a downlink signal in a wireless communication system, at least one processor; and At least one computer memory operably connectable to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations; The above operations include an operation of attempting to detect a synchronization block (SSB) on a specific frequency band supporting a terrestrial network (TN) and a non-terrestrial network (NTN), and performing an initial access procedure based on the detected SSB. A processing device wherein the attempt to detect the SSB is performed with priority on a cell with a higher priority among the TN cell and the NTN cell based on the priorities set for the TN cell and the NTN cell.

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