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

Abstract

In one embodiment, a UE attempts to detect an SSB on a first frequency band supporting TN and NTN, and performs an initial access procedure based on the detected SSB, in which an attempt to detect an SSB may be preferentially performed on a cell having a high priority among the TN cell and the NTN cell based on priorities set for the TN cell and the NTN cell.

Description

Technical Field

[0001] This disclosure relates to a wireless communication system. Background Technology

[0002] Various technologies, such as machine-to-machine (M2M) communication, machine-type communication (MTC), and various devices requiring high data throughput, such as smartphones and tablet PCs, have emerged and become widespread. Consequently, the data throughput that needs to be processed in cellular networks is rapidly increasing. To meet this rapidly increasing data throughput, carrier aggregation or cognitive radio technologies have been developed for the efficient use of more frequency bands, as well as multiple-input multiple-output (MIMO) or multi-base station (BS) cooperation technologies to improve the data transmission capacity on limited frequency resources.

[0003] Recently, there has been consideration of supporting wireless communication services through non-terrestrial networks (NTNs) to provide wireless communication services in areas where it is technically very difficult or costly to provide wireless communication services through terrestrial networks. Summary of the Invention

[0004] Technical issues

[0005] There is a need for a method to accurately and efficiently deliver wireless communication signals to user equipment (UE) via an airborne platform or space.

[0006] A method is needed for the efficient coexistence of terrestrial and non-terrestrial networks (NTN).

[0007] The purposes to be achieved by utilizing this disclosure are not limited to those specifically described above, and other purposes not described herein will become clearer to those skilled in the art through the following detailed description.

[0008] Technical solution

[0009] According to one aspect, a method for a user equipment (UE) to receive downlink signals in a wireless communication system, the method comprising the steps of: attempting to detect a synchronization signal block (SSB) on a first frequency band supporting terrestrial network (TN) cells and non-terrestrial network (NTN) cells; and performing an initial access procedure based on the detected SSB, wherein, based on priorities configured for the TN cells and the NTN cells, the step of attempting to detect the SSB is preferentially performed on the cell with higher priority among the TN cells and the NTN cells.

[0010] Based on the higher priority of the TN cell, the step of attempting to detect the SSB can be performed in the order of the TN cell to the NTN cell. 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 can be performed for one of the cells determined between the TN cell and the NTN cell based on the first threshold of the quality configuration for the SSB and the priority.

[0011] Since the quality of the second SSB is higher than the quality of the first SSB by the first threshold, even if the TN has a higher priority, the NTN cell can still be identified as one of the cells.

[0012] Based on the fact that the quality of the first SSB is not lower than the quality of the second SSB by the first threshold, the TN cell with the higher priority can be identified as the cell.

[0013] Based on the detection of an SSB including indication information indicating the presence of a low-priority cell in the SSB and a second threshold, and the quality of the SSB being lower than the second threshold, the UE may attempt to detect the SSB for the low-priority cell in the TN cell and the NTN cell.

[0014] The priority can be configured based on at least one of the UE's type, mobility, communication environment, and service requirements.

[0015] Based on whether the UE is of the massive machine-type communication (mMTC), vehicle-to-everything (V2X), or narrowband Internet of Things (NB-IoT) type, the NTN can be configured to have a higher priority than the TN.

[0016] According to another aspect, a user equipment (UE) for receiving downlink signals in a wireless communication system, the UE comprising: at least one transceiver; at least one processor; and at least one computer memory operatively connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, wherein the operations include: attempting to detect a synchronization signal block (SSB) in a first frequency band supporting terrestrial network (TN) cells and non-terrestrial network (NTN) cells, and performing an initial access procedure based on the detected SSB, and wherein, based on priorities configured for the TN cells and the NTN cells, the operation of attempting to detect the SSB is preferentially performed on the cell with higher priority among the TN cells and the NTN cells.

[0017] These objectives are merely some examples in this disclosure, and those skilled in the art can deduce and understand various examples reflecting the technical features of this disclosure based on the following detailed description.

[0018] Beneficial effects

[0019] According to some implementations of this disclosure, wireless communication signals can be transmitted / received efficiently via an air platform or in space. Therefore, the overall throughput of the wireless communication system can be increased.

[0020] According to some implementations of this disclosure, the continuity of wireless communication services can be ensured, the reliability of wireless communication services can be enhanced through connectivity between various access technologies, and network resilience and reliability in the face of disasters can be improved.

[0021] According to some implementations of this disclosure, the coexistence of non-terrestrial networks (NTN) and terrestrial networks (NT) can be supported.

[0022] According to some implementations of this disclosure, even when the network coexists on NTN and TN frequency bands, the user equipment (UE) can effectively detect synchronization signal blocks (SSBs).

[0023] The effects of the various embodiments are not limited to those specifically described above, and other effects not described herein will be more clearly understood by those skilled in the art in connection with this disclosure from the following detailed description. Attached Figure Description

[0024] The accompanying drawings are intended to provide an understanding of the present disclosure, illustrate various embodiments of the present disclosure, and, together with the description in the specification, serve to explain the principles of the present disclosure.

[0025] Figure 1 An example of a communication system 1 that applies the implementation of the present disclosure is shown.

[0026] Figure 2 This is a block diagram illustrating an example of a communication device capable of performing the methods according to this disclosure.

[0027] Figure 3 An example of a frame structure used in a 3GPP-based wireless communication system is shown.

[0028] Figure 4 An example of a time-slot resource grid is shown.

[0029] Figure 5 Multi-beam operation in a 3GPP-based system is illustrated.

[0030] Figure 6 An example of sending SS / PBCH blocks on a cell is shown.

[0031] Figure 7 An example of a non-terrestrial network (NTN) structure is shown.

[0032] Figure 8 Examples of synchronization grids and channel grids used in some implementations are shown.

[0033] Figure 9 An example of an SSB structure is shown.

[0034] Figure 10 The example illustrates the coexistence of terrestrial networks (TN) and non-terrestrial networks (NTN).

[0035] Figure 11 and Figure 12 This diagram illustrates the method by which a UE attempts to detect an SSB based on priority.

[0036] Figure 13 This is a diagram illustrating the method for configuring / determining priorities between TN and NTN cells.

[0037] Figures 14 to 16 This diagram illustrates the method by which a UE performs cell search in the first frequency band where NTN and TN cells coexist. Detailed Implementation

[0038] In the following, embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description given below with reference to the drawings is intended to explain exemplary implementations of the present disclosure, and not to show the only implementations that can be implemented according to the present disclosure. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that the present disclosure can be practiced without such specific details.

[0039] In some cases, known structures and devices may be omitted or shown in block diagram form, focusing on the essential features of the structures and devices without obscuring the concept of this disclosure. Throughout this disclosure, the same reference numerals will be used to refer to the same or similar parts.

[0040] The technologies, devices, and systems described below can be applied to a variety of wireless multiple access systems.

[0041] For ease of description, the description will be based on communication systems according to the 3rd Generation Partnership Project (3GPP). However, the technical features of this disclosure are not limited thereto. For example, although the following detailed description is based on 3GPP LTE or 5G technology, some implementations of this disclosure are applicable to any other mobile communication system and systems to be introduced in the future (e.g., 6G), unless they are specific to 3GPP LTE / 5G.

[0042] For terms and techniques not described in detail in this disclosure, reference may be made to 3GPP-based standard specifications, such as 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, 3GPP TS 38.213, and 3GPP TS 36.331, 3GPP TS 37.213, 3GPP TS 38.211, 3GPP TS 38.212, 3GPP TS 38.213, and 3GPP TS 38.213. 38.214, 3GPP TS 38.300, 3GPP TS 38.321, 3GPP TS 38.322, 3GPP TS 38.323, 3GPP TS 38.331, etc.

[0043] In the examples of this disclosure described later, if the apparatus “assumes” something, this could mean that the channel transmitting entity transmits the channel according to the corresponding “assumption.” It could also mean that the channel receiving entity receives or decodes the channel in a manner consistent with the “assumption,” provided that the channel has already been transmitted according to the “assumption.”

[0044] In this disclosure, a user equipment (UE) can be fixed or mobile. Various devices that transmit and / or receive user data and / or control information by communicating with a base station (BS) can be UEs. The term UE can be referred to as a terminal device, mobile station (MS), mobile terminal (MT), user terminal (UT), subscriber station (SS), radio device, personal digital assistant (PDA), wireless modem, handheld device, etc. In this disclosure, a BS refers to a fixed station that communicates with a UE and / or another BS and exchanges data and control information with the UE and another BS. The term BS can be referred to as an advanced base station (ABS), node-B (NB), evolved node-B (eNB), gNB, base transceiver system (BTS), access point (AP), processing server (PS), etc. Specifically, a BS for Universal Terrestrial Radio Access (UTRAN) is referred to as an NB, a BS for Evolved UTRAN (E-UTRAN) is referred to as an eNB, and a BS for New Radio Access Technology networks is referred to as a gNB. In the following, for ease of description, NB, eNB, or gNB will be referred to as BS, regardless of the type or version of the communication technology.

[0045] In this disclosure, a node refers to a fixed point capable of sending / receiving radio signals to / from a UE via communication with the UE. Various types of BSs can be used as nodes, regardless of their names. Each node is equipped with at least one antenna. An antenna can refer to a physical antenna port or a virtual antenna or antenna array. A node can also be referred to as a point.

[0046] 3GPP-based communication systems use the concept of cells to manage radio resources. The cells associated with radio resources differ from cells in geographical areas. A "cell" in a geographical area can be understood as the coverage area within which a node can provide service using a carrier, while a "cell" in radio resources is associated with bandwidth (BW), which is the frequency range configured by the carrier. Since the DL coverage area, which is the range within which a node can transmit a valid signal, and the UL coverage area, which is the range within which a node can receive a valid signal from a UE, depend on the carrier carrying the signal, a node's coverage area can also be associated with the coverage area of ​​the "cell" of radio resources used by the node. Therefore, the term "cell" can be used to indicate the service coverage area of ​​a node at some point, the radio resources at other times, or the range within which a signal using a radio resource can reach with effective strength at other times.

[0047] A “cell” associated with radio resources is defined by a combination of DL resources and UL resources, i.e., a combination of DL component carriers (CCs) and UL CCs. A cell can be configured with only DL resources or a combination of DL and UL resources. If carrier aggregation is supported, the relationship between the carrier frequencies of the DL resources (or DL ​​CCs) and the carrier frequencies of the UL resources (or UL CCs) can be indicated by system information. In this case, the carrier frequencies can be equal to or different from the center frequency of each cell or CC.

[0048] In a wireless communication system, the UE receives information from the BS on the DL and transmits information to the BS on the 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 / purpose of the information transmitted and / or received by the UE and BS.

[0049] 3GPP-based communication standards define DL physical channels corresponding to resource elements carrying information from higher layers and DL physical signals corresponding to resource elements used by the physical layer but not carrying information from higher layers. For example, the Physical Downlink Shared Channel (PDSCH), Physical Broadcast Channel (PBCH), and Physical Downlink Control Channel (PDCCH) are defined as DL physical channels, and Reference Signals (RS) and Synchronization Signals (SS) are defined as DL physical signals. RS, also known as pilot signals, represents signals with predefined special waveforms known to both the BS and UE. For example, Demodulation Reference Signal (DMRS) and Channel State Information RS (CSI-RS) are defined as DL RS. 3GPP-based communication standards also define UL physical channels corresponding to resource elements carrying information from higher layers and UL physical signals corresponding to resource elements used by the physical layer but not carrying information from higher layers. For example, the Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH), and Physical Random Access Channel (PRACH) are defined as UL physical channels, and DMRS for UL control / data signals and SRS for UL channel measurements are defined.

[0050] In this disclosure, PDCCH refers to a set of time-frequency resources (e.g., resource elements (REs)) that are a set of REs carrying downlink control information (DCI), and PDSCH refers to a set of time-frequency resources that are a set of REs carrying DL data. PUCCH, PUSCH, and PRACH refer to a set of time-frequency resources that are sets of time-frequency REs carrying uplink control information (UCI), UL data, and random access preambles, respectively. In the following description, "UE / BS transmits / receives PUCCH / PUSCH / PRACH" means that the UE / BS transmits / receives UCI / UL data / random access preambles on or through PUCCH / PUSCH / PRACH. Additionally, "BS / UE transmits / receives PBCH / PDCCH / PDSCH" means that the BS / UE transmits / receives broadcast information / DCI / DL data on or through PBCH / PDCCH / PDSCH.

[0051] In this disclosure, radio resources (e.g., time-frequency resources) scheduled or configured by the BS to the UE for the transmission or reception of PUCCH / PUSCH / PDSCH can be referred to as PUCCH / PUSCH / PDSCH resources.

[0052] Since the communication device receives physical channels and / or physical signals in the form of radio signals on the cell, the communication device can select and receive radio signals that only include specific physical channels or specific physical signals without using a radio frequency (RF) receiver, or select and receive radio signals that do not include specific physical channels or specific physical signals through an RF receiver. In practice, the communication device receives radio signals on the cell through an RF receiver, converts the radio signals, which are RF band signals, into baseband signals, and then uses one or more processors to decode the physical signals and / or physical channels in the baseband signals. Therefore, in some implementations of this disclosure, not receiving physical signals and / or physical channels may mean that the communication device does not attempt to recover physical signals and / or physical channels from radio signals, for example, does not attempt to decode physical signals and / or physical channels, rather than that the communication device actually does not receive radio signals that include the corresponding physical signals and / or physical channels.

[0053] Figure 1 An example of a communication system 1 that applies the implementation of the present disclosure is shown.

[0054] Reference Figure 1 The communication system 1 applied in this disclosure includes a wireless device, a BS, and a network. Here, a wireless device refers to a device that performs communication using wireless access technologies (e.g., 5G NR (New RAT), LTE (e.g., E-UTRA), WiFi, or 6G, which will be introduced in the future).

[0055] Wireless devices may include, but are not limited to, robots 100a, vehicles 100b-1, 100b-2, 100b-3 and 100b-4, extended reality (XR) devices 100c, handheld devices 100d, home appliances 100e, Internet of Things (IoT) devices 100f, and artificial intelligence (AI) devices / servers 400. For example, vehicles may include ground vehicles with wireless communication capabilities, autonomous vehicles, and vehicles capable of performing vehicle-to-vehicle communication. Here, vehicles may include unmanned aerial vehicles (UAVs) (e.g., drones) and urban air traffic (UAM) (e.g., unmanned aerial vehicles). XR devices may include augmented reality (AR) / virtual reality (VR) / mixed reality (MR) devices. Handheld devices may include smartphones, smart tablets, wearable devices (e.g., smartwatches or smart glasses), and computers (e.g., laptops). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors and smart meters. For example, a BS and network may also be implemented as wireless devices, and a particular wireless device may operate as a BS / network node relative to another wireless device.

[0056] Wireless devices 100a to 100f can connect to the network via BS 200. Artificial intelligence (AI) technology can be applied to wireless devices 100a to 100f, and wireless devices 100a to 100f can connect to AI server 400 via the network. While wireless devices 100a to 100f can communicate with each other via BS 200 / network, they can also perform direct communication with each other without going through the BS / network (e.g., sidelink communication). For example, vehicles 100b-1, 100b-2, 100b-3, and 100b-4 can perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). IoT devices (e.g., sensors) can perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0057] Wireless communication / connections can be established between wireless devices 100a to 100f and BS 200, as well as between wireless devices 100a to 100f. Here, wireless communication / connections such as UL / DL communication and side-link (SL) communication (or device-to-device (D2D) communication) can be established using various wireless access technologies (e.g., 5G NR). The wireless devices and the BS / wireless devices can transmit / receive radio signals to / from each other via wireless communication / connections (UL / DL, SL). For this purpose, at least a portion of various configuration information configuration processes, various signal processing processes (e.g., channel coding / decoding, modulation / demodulation, and resource mapping / demapping), and resource allocation processes for transmitting / receiving radio signals can be performed based on various proposals of this disclosure.

[0058] Figure 2 This is a block diagram illustrating an example of a communication device capable of performing the methods according to this disclosure. (See also...) Figure 2 The first wireless device 100 and the second wireless device 200 can transmit and / or receive radio signals using various wireless access technologies. Here, {first wireless device 100 and second wireless device 200} can correspond to... Figure 1 {Wireless Device 100x and BS200} and / or {Wireless Device 100x and Wireless Device 100x}.

[0059] The first wireless device 100 and the second wireless device 200 may include one or more processors 102 and 202 and one or more memories 104 and 204, and additionally include one or more transceivers 106 and 206 and / or one or more antennas 108 and 208, respectively. Processors 102 and 202 may control memories 104 and 204 and / or transceivers 106 and 206, and may be configured to implement the functions, processes, and / or methods described / presented below. For example, processors 102 and 202 may process information in memories 104 and 204 to generate first information / signals, and then transmit radio signals including the first information / signals via transceivers 106 and 206. Processors 102 and 202 may receive radio signals including second information / signals via transceivers 106 and 206, and then store the information obtained by processing the second information / signals in memories 104 and 204. Memory 104 and 204 may be connected to processor 102 and 202 and may store various information related to the operation of processor 102 and 202. For example, memory 104 and 204 may execute part or all of a process controlled by processor 102 and 202, or store software code including instructions for performing the processes and / or methods described / presented later. Here, processor 102 and 202 and memory 104 and 204 may be part of a communication modem / circuit / chip designed to implement a wireless access technology. Transceiver 106 and 206 may be connected to processor 102 and 202 and transmit and / or receive radio signals via one or more antennas 108. Each of transceiver 106 and 206 may include a transmitter and / or a receiver.

[0060] One or more protocol layers may be implemented by, but not limited to, one or more processors 102 and 202. For example, one or more processors 102 and 202 may implement one or more layers (e.g., functional layers, such as the Physical (PHY) layer, Media Access Control (MAC) layer, Radio Link Control (RLC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Resource Control (RRC) layer, and Service Data Adaptation Protocol (SDAP) layer). One or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the functions, processes, proposals, and / or methods disclosed in this disclosure. One or more processors 102 and 202 may generate messages, control information, data, or information according to the functions, processes, proposals, and / or methods disclosed in this disclosure. One or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information, according to the functions, processes, suggestions, and / or methods disclosed in this disclosure, and provide the generated signals to one or more transceivers 106 and 206. One or more processors 102 and 202 may receive signals (e.g., baseband signals) from one or more transceivers 106 and 206, and acquire PDUs, SDUs, messages, control information, data, or information according to the functions, processes, suggestions, and / or methods disclosed in this disclosure.

[0061] One or more processors 102 and 202 may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof, and the firmware or software may be configured to include modules, processes, or functions. Firmware or software configured to perform the functions, processes, suggestions, and / or methods disclosed in this disclosure may be included in one or more processors 102, 202, or stored in one or more memories 104, 204 for being driven by one or more processors 102, 202. The functions, processes, suggestions, and / or methods disclosed in this disclosure may be implemented using firmware or software in the form of code, commands, and / or command sets.

[0062] One or more memories 104 and 204 may be connected to one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, commands, and / or instructions. One or more memories 104 and 204 may be located internally and / or externally to one or more processors 102 and 202. One or more memories 104 and 204 may be connected to one or more processors 102 and 202 via various technologies such as wired or wireless connections.

[0063] One or more transceivers 106 and 206 can transmit / receive user data, control information, and / or radio signals / channels mentioned in the methods and / or operation flowcharts disclosed herein to / from one or more other devices. Additionally, one or more processors 102, 202 can perform control such that one or more transceivers 106, 206 can transmit / receive user data, control information, or radio signals to / from one or more other devices. One or more transceivers 106 and 206 can be connected to one or more antennas 108 and 208. One or more transceivers 106 and 206 can be configured to transmit and / or receive user data, control information, and / or radio signals / channels mentioned in the functions, processes, suggestions, methods, and / or operation flowcharts disclosed herein via one or more antennas 108 and 208. In this disclosure, one or more antennas can be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers 106 and 206 can convert received radio signals / channels, etc., from RF band signals to baseband signals so that the received user data, control information, radio signals / channels, etc., can be processed by one or more processors 102 and 202. For this purpose, one or more transceivers 106 and 206 may include (analog) oscillators and / or filters.

[0064] According to the example, the first wireless device 100 or UE may include a processor 102 and a memory 104 connected to the RF transceiver 106. The memory 104 may include at least one program for executing commands described below. Figures 10 to 15 The described implementation involves operations related to the following methods. Specifically, the operations include attempting to detect synchronization blocks (SSBs) on specific frequency bands supporting terrestrial networks (TN) and non-terrestrial networks (NTN) and performing an initial access procedure based on the detected SSBs. In this case, based on the priorities set for TN and NTN cells, attempts to detect SSBs can be preferentially made on network cells with higher priority among TN and NTN cells.

[0065] In this disclosure, at least one memory 104 and 204 may store instructions or programs that, when executed, cause at least one processor 102 and 202 operatively coupled to at least one memory to perform operations according to some embodiments or implementations of this disclosure.

[0066] In this disclosure, a computer-readable (non-transitory) storage medium may store at least one instruction or computer program that, when executed by at least one processor, causes the at least one processor to perform operations according to some embodiments or implementations of this disclosure.

[0067] Figure 3 An example of a frame structure used in a 3GPP-based wireless communication system is shown.

[0068] Figure 3 The frame structure described is purely exemplary, and the number of subframes, time slots, and symbols within a frame can vary. In some wireless communication systems, different sets of OFDM parameters (e.g., subcarrier spacing (SCS)) can be configured for multiple cells aggregated for a single UE. Therefore, the (absolute time) duration of time resources comprising the same number of symbols (e.g., subframes, time slots, or transmission time intervals (TTI)) can be configured differently for the aggregated cells. Here, symbols can include OFDM symbols (or cyclic prefix-OFDM (CP-OFDM) symbols) and SC-FDMA symbols (or discrete Fourier transform-extended-OFDM (DFT-s-OFDM) symbols). In this disclosure, symbols, OFDM-based symbols, OFDM symbols, CP-OFDM symbols, and DFT-s-OFDM symbols are used interchangeably.

[0069] Reference Figure 3 UL and DL transmissions are organized into frames. Each frame has a T f = (△f max N f / 100) T c = Duration of 10 ms, where the basic time unit is T. c = 1 / (△f max N f ), △f max = 480 10 3 Hz and N f =4096. For reference, the sampling time is T. s = 1 / (△f ref N f,ref ), △f ref = 15 10 3 Hz and N f,ref =2048. T c and T f Having a constant = T c / T f = 64. One frame consists of 10 subframes, and the duration T of a single subframe is... sf The duration is 1 ms. Subframes are further divided into time slots, and the number of time slots in a subframe depends on the subcarrier interval. Each time slot can include a cyclic prefix (CP) based... N slot symb The number of symbols. For example, in some scenarios, each time slot in a normal CP consists of 14 OFDM symbols, while in an extended CP, each time slot consists of 12 OFDM symbols. The parameter set depends on the exponentially scalable subcarrier spacing Δf = 2. u 15 kHz. The following figure shows the subcarrier spacing Δf = 2 for a normal CP. u 15kHz, number of OFDM symbols per time slot ( N slot symb ), number of time slots per frame ( N frame,u slot ) and the number of time slots in each subframe ( N subframe,u slot ).

[0070] [Table 1] .

[0071] The following table shows the result based on the subcarrier spacing Δf = 2. u 15 kHz, number of OFDM symbols per time slot, number of time slots per frame, and number of time slots per subframe.

[0072] [Table 2] .

[0073] For the subcarrier spacing configuration u, the time slots can be indexed in ascending order within the subframe as follows: n u s ∈ {0, ...,n subframe,u slot - 1}, and the following indexing within the frame in ascending order: n u s,f ∈ {0, ..., n frame,u slot - 1}.

[0074] In the following description, embodiments of this disclosure will be referred to as time slots by the term "minimum time unit" used for scheduling uplink, downlink, and sidelink transmissions. However, depending on the wireless communication system, the minimum time unit used for scheduling may be referred to by different terms. For example, in LTE-based systems, the minimum time unit used for scheduling transmissions is called a subframe or transmission time interval (TTI), while in NR-based systems, the minimum time unit used for scheduling is called a time slot.

[0075] Figure 4 An example of a resource grid with time slots is shown. A time slot comprises multiple slots in the time domain (e.g., ...). N slot symb (Number) symbols. For each parameter set (e.g., subcarrier spacing) and carrier, a Common Resource Block (CRB) is defined from the signaling of higher-level layers (e.g., Radio Resource Control (RRC) signaling). N start,u grid The beginning N size,u grid,x N RB sc Subcarriers and N subframe ,u symb A resource grid of OFDM symbols. Here, N size,u grid,x It 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 This refers to the number of subcarriers per RB in a 3GPP-based wireless communication system. N RB sc Typically 12. For a given antenna port p, subcarrier spacing configuration u, and transmission link (DL or UL), there exists a resource grid. The carrier bandwidth used for the subcarrier spacing configuration u... N size,u gridThe parameters are provided to the UE by higher-level parameters (e.g., RRC parameters). Each element in the resource grid used for antenna port p and subcarrier spacing configuration u is called a resource element (RE), and a complex 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 representing the symbol position relative to a reference point in the time domain. RBs are classified into CRBs and Physical Resource Blocks (PRBs). For subcarrier spacing configuration u, CRBs are numbered from 0 upwards in the frequency domain. The center of subcarrier 0 in CRB 0 for subcarrier spacing configuration u is equal to "point A," which serves as the common reference point for the RB grid. The PRBs for subcarrier spacing configuration u are defined within the bandwidth portion (BWP) and are numbered from 0 to... N size,u BWP,i -1 is the number, where i is the BWP number. PRB n in BWP i PRB With CRB n u CRB The relationship between them is given by the following formula: n u PRB = n u CRB + N start,u BWP,i ,in N start,u BWP,i It is relative to CRB 0, where the BWP begins. The BWP comprises multiple consecutive RBs in the frequency domain. For example, the BWP can be a given set of parameters u in BWP i for a given carrier. i A subset of defined consecutive CRBs. A carrier may include 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 active BWPs, and only a predetermined number of BWPs (e.g., one BWP) configured for the UE can be active on the corresponding carrier.

[0076] In a 3GPP-based system, a control resource set (CORESET) can be defined and / or configured, which is a set of time-frequency resources that the UE can monitor for PDCCH. One or more CORESETs can be configured for the UE. A CORESET has a duration of one to three OFDM symbols and includes a set of physical resource blocks (PRBs). The PRBs constituting the CORESET and the CORESET duration can be provided to the UE via upper-layer (e.g., RRC) signaling. Within the configured CORESET, a set of PDCCH candidates is monitored according to the corresponding search space set. In this disclosure, monitoring means decoding each PDCCH candidate according to the monitored DCI format (so-called blind decoding). The Master Information Block (MIB) on the PBCH provides the UE with parameters (e.g., CORESET#0 configuration) for monitoring the PDCCH to schedule the PDSCH carrying System Information Block 1 (SIB1). The PBCH can also indicate that there is no associated SIB1, in which case the UE can be instructed to search for SSBs associated with SIB1 on other frequencies, as well as frequency ranges assuming no SSBs associated with SSB1 exist. CORESET#0 is used to schedule at least SIB1 CORESETs and can be configured via MIB or dedicated RRC signaling.

[0077] The set of PDCCH candidates monitored by the UE is defined based on the PDCCH search space set. The search space set can 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 a CORESET configuration.

[0078] Figure 5 Multi-beam operation in a 3GPP-based system is illustrated.

[0079] 5G and subsequent 3GPP-based systems can utilize high and ultra-high frequency bands (such as millimeter bands equal to or greater than 6 GHz) to transmit data to multiple users while maintaining high data rates through the use of wideband. However, millimeter bands have frequency characteristics that cause very rapid signal attenuation over distance due to the use of excessively high frequency bands. Therefore, when using frequency bands of at least 6 GHz or higher, 3GPP-based systems employ narrow-beam transmission schemes. These schemes address the reduced coverage caused by rapid propagation attenuation by concentrating energy in a specific direction rather than omnidirectionally, and perform signal transmission to compensate for the rapid propagation attenuation characteristics. However, when only one narrow beam is used to provide service, the range that a single BS can provide service is narrowed, and therefore the BS collects multiple narrow beams and provides service by using a wideband.

[0080] Figure 6 An example of sending SS / PBCH blocks on a cell is shown.

[0081] In 3GPP-based systems, each SSB is associated with a specific beam. For example, during a half-frame, different SSBs can be transmitted in different spatial directions (using different beams spanning the coverage area of ​​the cell). The possible temporal positions of an SSB within a half-frame are determined by the subcarrier spacing, and the period of the half-frame in which the SSB is transmitted is configured by the network. Multiple SSBs can be transmitted within the frequency span of a carrier. Different indices of SSBs transmitted / detected on a single cell can correspond to different BS (wide) Tx beams. In 3GPP-based systems, multi-beam operation is based on beam switching / beam pushbroom, where signals are transmitted / received while the beam direction changes over time. For example, assuming the BS supports up to N transmit beams, beam pushbroom can be performed to transmit a synchronization signal block (SSB) including PSS, SSS, and PBCH in each of up to N beam directions (see [link to relevant documentation]). Figure 5 (SSB beambroom in the context of beambroom). The set of SSBs within a beambroom is specifically referred to as the SS burst set or SS burst. The number of SSBs in the SS burst set represents the number of beams used for beambroom. Multiple SSB modes are defined based on the frequency band and subcarrier spacing (SCS). In this disclosure, the SSB mode is also referred to as the SSB timing mode. For a half-frame with SSBs, the first (OFDM) symbol index s of the candidate SSB can be determined according to the SCS of the SSBs as follows, where index 0 corresponds to the first symbol of the first time slot in the half-frame. In some scenarios, the SSB modes according to the following table can be used.

[0082] [Table 3]

[0083] In the table above, FR represents the frequency range. For example, FR1 can correspond to a frequency range of 410 MHz to 7,125 MHz, and FR2 can correspond to a frequency range of 24,250 MHz to 52,600 MHz. As can be seen from the table, the number of SSBs within an SSB burst set can vary depending on the frequency range and the SCS. The number of candidate SSBs in a half-frame can be ordered in ascending time from 0 to L'. max -1 is added to the index. If L max If L' is the maximum number of SSB indexes within the cell or the maximum number of SSBs transmitted within half a frame, then for operations without shared spectrum channel access, L' max = L max For operations with shared spectrum channel access, L'max and L max They can be different. For example, in the case of shared spectrum channel access in FR1, for L' max SSB of SCS at 10 and 15 kHz, and for L' max For SSCs of 20 and 30 kHz, the SSB can be defined as L. max =8.

[0084] SSBs are transmitted periodically from 5 ms to 160 ms. A UE performing initial access to the network assumes 20 ms (e.g., 2 frames). In other words, for initial cell access, the UE can assume that half-frames with SSBs occur in a two-frame period.

[0085] Return to reference Figure 5 The UE can measure the power of SSBs received from the BS transmission (Tx) beam using a wide receive (Rx) beam and select its preferred beam. For example, the UE can select an SSB from those detected / received. 3GPP-based systems specify a particular mapping between SSBs and Random Access Channel (RACH) timings to allow the network to know which beam the UE has selected. RACH timings are time and frequency resources available for transmitting RACH preambles. Information about how many SSBs will be mapped to a RACH timing and how many preamble indices will be mapped to a single SSB can be provided to the UE by the network. For example, when the network configures the number of SSBs per RACH timing to 1 / N, one SSB is associated with N RACH timings (where N is a positive integer), and when the network configures the number of SSBs per RACH timing to N, N preamble indices are mapped to a single SSB. The UE selects SSBs from those detected / received by the UE on the cell and selects the RACH timing for transmission based on the selected SSB. The BS can detect which SSB is being transmitted on the cell already selected by the UE by detecting the RACH timing, including the PRACH from the UE, through BS Rx beam pushbroom. The BS can then determine the BS Tx beam used for communication with the UE based on the SSB selected by the UE.

[0086] For finer beam tuning, CSI-RS can be transmitted. The BS can perform beamfining by using CSI-RS transmissions in a narrower beam around the BS Tx beam, determined based on the RACH timing of the detected PRACH from the UE (see [link to documentation]). Figure 5(CSI-RS beam pushbroom in the BS Tx). The UE can measure the power of the CSI-RS received from the BS Tx narrow beam and report to the BS which BS Tx narrow beam the UE prefers. For example, the UE can measure the CSI-RS on a CSI-RS resource to select at least one CSI-RS resource and report the CSI-RS Resource Indicator (CRI) and the corresponding Reference Signal Received Power (RSRP) of the selected CSI-RS resource to the BS. The BS can determine the BS Tx narrow beam based on the CRI and / or the corresponding RSRP reported by the UE and repeatedly transmit CSI-RS with the BS Tx narrow beam (see [link to documentation]). Figure 5 The P3 CSI-RS beam pushbroom in the UE enables the UE to perform Rx beam pushbroom to find the appropriate UE Rx beam. The UE can find the appropriate UE Rx beam by measuring the power of the CSI-RS received from each UE Rx beam.

[0087] A UE can detect beam faults using CSI-RS / SSB. For example, when the L1-RSRP of the beam to be connected falls below a certain limit, the UE identifies a beam fault and searches for other candidate beams with good quality. If a predetermined number of beam faults are detected, a Beam Fault Recovery (BFR) procedure can be triggered using the candidate beams. The network can provide the UE with the identifier (ID) of the SSB sent by the cell to determine the candidate beams for BFR, as well as the preamble index used when performing BRF to select the candidate beam identified by the SSB. When a predetermined number of beam faults are detected, the UE sends a BRF request to the network by sending a PRACH associated with the SSBID, and the network provides a Random Access Response (RAR) to the UE in response to the BRF request.

[0088] 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. Transmission Configuration Indicator (TCI) states can be configured / indicated for the PDCCH / PDSCH. TCI states can include quasi-co-location (QCL) information. For example, to decode a PDSCH based on a detected PDCCH with DCI for a given serving cell, the UE can be configured with M TCI states provided by the BS via upper-layer parameters. Each TCI state includes parameters configuring the QCL relationship between one or two downlink reference signals (DLRS) and the DM-RS port of the PDSCH, the DM-RS port of the PDCCH, or the CSI-RS port of the CSI-RS resource. The QCL relationship is configured by upper-layer parameter qcl-type1 for the first DLRS and upper-layer parameter qcl-type2 (if configured) for the second DLRS. The QCL type corresponding to each DL RS is given by the upper-level parameter qcl-type in QCL-Info, and can take one of the following values.

[0089] - "typeA": {Doppler frequency shift, Doppler spread, average delay, delay spread}

[0090] - "typeB": {Doppler shift, Doppler spread}

[0091] - "typeC": {Doppler shift, average delay}

[0092] - "typeD": {space Rx parameter}

[0093] Figure 7 An example of a non-terrestrial network (NTN) structure is shown.

[0094] Recently, there has been discussion about enabling 3GPP-based systems to support non-terrestrial networks (NTNs). NTNs are any network that includes non-terrestrial flying objects. When wireless communication via NTNs becomes possible in 3GPP-based systems, the continuity of wireless communication services can be ensured, the reliability of wireless communication services can be enhanced through connectivity between various access technologies, and network resilience and reliability in the face of disasters can be improved. For ease of explanation, the following terminology will be used.

[0095] - NTN: The radio access network including the BS, which provides non-terrestrial radio access to the UE by using NTN payloads and NTN gateways installed in the air or on space-based NTN vehicles.

[0096] - NTN Gateway: A ground station located on the Earth's surface that provides connectivity to NTN payloads via feeder links. An NTN gateway is a Transport Network Layer (TNL) node.

[0097] - NTN payload: A network node installed on a satellite or high-altitude platform station to provide connectivity between the service link and the feeder link.

[0098] - Service Link: The radio link between the NTN payload and the UE.

[0099] - Feeder Link: The wireless link between the NTN gateway and the NTN payload.

[0100] - Satellite: A space vehicle that carries NTN payloads and orbits the Earth.

[0101] - NTN cell: A cell that provides a service link between the UE and the NTN payload.

[0102] Reference Figure 7 The NTN gateway connects to the NTN payload installed on a satellite or High Altitude Platform System (HAPS) via a feeder link. The NTN payload connects to the UE via a serving link. The NTN gateway can connect to the core network of a 3GPP-based system.

[0103] NTN payloads forward radio protocols received from the UE (via the serving link) to the NTN gateway (via the feeder link), and forward radio protocols received from the NTN gateway (via the feeder link) back to the UE (via the feeder link). An NTN gateway can serve multiple NTN payloads, and NTN payloads can be served by multiple NTN gateways. For NTN, the tracking area can correspond to a fixed geographical area, and each mapping can be configured in the radio access network.

[0104] The following three types of service links are supported: - Fixed Earth service link: A service link provided by a beam that continuously covers the same geographic area (e.g., in the case of GSO satellites).

[0105] - Quasi-Earth Fixed Service Link: A service link provided by a beam that covers one geographic area for a limited time period and another geographic area for a different time period (e.g., in the case of NGSO that generates a steerable beam).

[0106] - Earth mobile service links: Service links whose coverage area is provided by beams that slide across the Earth's surface (e.g., for NGSO satellites that generate fixed or unmanipulated beams).

[0107] NTN can include satellite communication networks, air-to-ground networks, and UAV networks. One of the key concepts of 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 satellite position estimation information. Based on this satellite position estimation information, the network can predict feeder link handovers and manage UE mobility and radio resource control. The BS providing NTN access can broadcast orbital trajectory information or ephemeris information about the coordinates of the NTN payload. Ephemeris information can provide satellite position estimates in the format of position and velocity state vectors or in the format of orbital parameters. The following shows a description of the EphemerisInfo information element and fields broadcast by the BS.

[0108] [Table 4] .

[0109] [Table 5]

[0110] Satellite communication networks can include low Earth orbit (LEO) satellites, medium Earth orbit (MEO) satellites, and geostationary orbit (GEO) satellites.

[0111] [Table 6] .

[0112] [Table 7] .

[0113] Figure 8 Examples of synchronization grids and channel grids used in some implementations are shown.

[0114] A UE attempting network access performs a cell search, which is the process by which the UE obtains time and frequency synchronization with the cell and detects the cell's Physical Layer Cell Identifier (PCI). During the cell search operation performed at power-on, the UE obtains the necessary information for cell access by using the SSB. The UE performing the cell search attempts to detect the SSB as it moves through the frequency domain, assuming a synchronization grid. When there is no explicit signaling for the SSB location, the synchronization grid indicates the possible frequency location of the SSB that the UE will use to obtain system information. In LTE, the frequency domain location of the PSS / SSS is always fixed near the carrier center frequency (see reference). Figure 8(a)). In contrast, in NR, a set of possible frequency locations for the SSB is defined based on the frequency band, called the synchronization grid, and the UE needs to search for the SSB based on this synchronization grid. Unlike LTE, where the UE searches for the PSS / SSS at all carrier grid locations, a sparser synchronization grid is defined in the UE in NR (see (a)). Figure 8 (b) Therefore, in NR, the UE needs to search for the SSB in a sparser synchronization grid compared to LTE. The carrier grid, also known as the channel grid, represents possible carrier locations. The global frequency channel grid defines a set of radio frequency (RF) frequencies F REF The RF reference frequency is used in signaling to identify the location of RF channels, SSB blocks, and other components. A global frequency grid is used to define all frequencies from 0 to 100 GHz. In NR, the RF reference frequency can be given by the NR absolute radio channel number (NR-ARFCN), and the RF reference frequency FREF in MHz can be given by the following equation: F REF = F REF-Offs + △F Global (N REF - N REF-Offs ), where △F Global It is the granularity of the frequency grid, N REF It is NR-ARFCN, and F REF-Offs and N REF-Offs The following table can be used to provide the information.

[0115] [Table 8] .

[0116] The channel grid defines a subset of RF reference frequencies that will be used to identify the location of RF channels in the uplink and downlink.

[0117] A global synchronization grid is defined for all frequencies, and the frequency position of the SSB is defined as the SS with the corresponding digital global synchronization signal number (GSCN). REF GSCN and SS are defined for all frequency ranges. REF The parameters are defined, for example, in the table below.

[0118] [Table 9] .

[0119] The synchronization grid for each frequency band can be given, for example, by the table below. The distance between applicable GSCN entries can be given by the <step size> indicated in the table below.

[0120] [Table 10]

[0121] The notes shown in Table 10 can be explained using the following table.

[0122] [Table 11]

[0123] Referring to Tables 9 and 10, for n35, the UE can perform cell search by incrementing the GSCN by 1 starting from GSCN=6125.

[0124] Cell selection is performed based on the SSB defined in the cell containing the synchronization grid (CD-SSB). An SSB is called a CD-SSB when it is associated with Residual Minimum System Information (RMSI) (e.g., SIB1), for example, when the MIB carried by the PBCH in the SSB includes parameters for the transmission of the PDCCH against the scheduling RMSI. The UE can search for frequency bands, identify the strongest cell based on the SSB for each carrier frequency, and select a cell to perform initial access.

[0125] SSB related operations

[0126] Figure 9 The SSB structure is shown. The UE can use the SSB for cell search, system information acquisition, beam alignment for initial access, DL measurements, etc. The SSB is interchangeable with the Synchronization Signal / Physical Broadcast Channel (SS / PBCH) block.

[0127] Reference Figure 9 The SSB comprises the PSS, SSS, and PBCH. The SSB consists of four consecutive OFDM symbols, and for each OFDM symbol, the PSS, PBCH, SSS / PBCH, and PBCH are transmitted. The PSS and SSS each consist of one OFDM symbol and 127 subcarriers, and the PBCH consists of three OFDM symbols and 576 subcarriers. Polar coding and Quadrature Phase Shift Keying (QPSK) are applied to the PBCH. The PBCH includes data REs and demodulation reference signals (DMRS) REs for each OFDM symbol. For each RB, there are three DMRS REs, and three data REs between the DMRS REs.

[0128] Cell search refers to the process by which a UE obtains time / frequency synchronization for a cell and detects the cell identifier (ID) (e.g., physical layer cell ID or PCID) of that cell. The PSS is used to detect cell IDs within a cell ID group, and the SSS is used to detect cell ID groups. The PBCH is used to detect the SSB (time) index and detect half-frames.

[0129] The UE's cell search process can be summarized in Table 12 below.

[0130] [Table 12] .

[0131] There are 336 cell ID groups, and each cell ID group contains 3 cell IDs. There are a total of 1008 cell IDs. Information about the cell ID group to which a cell ID belongs is provided / obtained through the cell's SSS (Social Security Service), and information about the cell IDs within the 336 cells of that cell ID group is provided / obtained through the PSS (Position Support Service).

[0132] Figure 10 The example illustrates the coexistence of terrestrial networks (TN) and non-terrestrial networks (NTN).

[0133] Reference Figure 10 When a UE is served by a BS of a TN, its receive (RX) beam can be directed towards the ground, and when a UE is served by a BS of an NTN, its RX beam can be directed towards the sky. For frequency bands where NTN and TN can coexist, the UE has no prior information about the BS type during initial access. In this case, during initial access, the UE may not know whether its RX beam for SSB reception needs to be oriented towards a TN-BS or an NTN-BS, and therefore the UE may randomly select the RX beam direction. When the randomly selected RX beam direction is inappropriate, cell search may take longer, which may lead to performance degradation. Therefore, NTN and TN coexistence requires NTN / TN differentiation technology. The following describes in detail a method for cell search and / or connection based on the priority between NTN and TN as an NTN / TN differentiation technology.

[0134] Priority-based NTN / TN cell search

[0135] The UE can detect / search for SSBs based on the synchronization grid to perform cell search for cell selection (or reselection). The UE can measure the power of the detected SSBs, select a specific SSB from the detected SSBs based on the measured power, and perform the initial access procedure for cell access based on that specific SSB.

[0136] As mentioned above, the UE can perform cell searches for operating frequency bands where NTN and TN coexist. In this case, the UE may not be aware of whether it is attempting to detect the SSB for an NTN cell or a TN cell during the cell search.

[0137] For ease of explanation, cells targeting NTN will be defined as NTN cells, cells targeting TN will be defined as TN cells, and either NTN or TN cells will be defined as network cells. Regarding priority-based cell search, even without a separate definition, it will be assumed that priorities are applied to cell searches between TN and NTN cells within the same synchronization grid.

[0138] Figure 11 and Figure 12 This diagram illustrates the method by which a UE attempts to detect an SSB based on priority.

[0139] As described above, the UE can attempt to detect SSBs for cell selection / search in a frequency band (or a first frequency band) where NTN and TN cells coexist. In this case, the UE can perform cell selection / search for NTN and TN cells based on priority. Here, the priority between TN and NTN cells can be pre-configured / predefined. The UE can perform cell search from higher-priority cells in the TN and NTN cells to lower-priority cells based on this priority. For example, when a TN cell is configured as a network cell with a higher priority than an NTN cell, the UE can attempt to detect an SSB for the NTN cell after attempting to detect an SSB for the TN cell.

[0140] In the following text, see reference Figure 11 This section details the scenario where SSB detection is attempted when the priority of a TN cell is higher than that of an NTN cell, and refers to... Figure 12 This section details the scenario where SSB detection is attempted when the NTN cell has a higher priority than the TN cell.

[0141] Reference Figure 11 The UE can attempt to prioritize the detection of SSBs that are expected / assumed to be associated with TN cells (which are high-priority network cells). For example, the UE can prioritize the detection of SSBs for TN cells over those for NTN cells by attempting to detect SSBs using a receive beam shaped in the ground direction (in which the TN cell may be located).

[0142] Then, if an SSB for a TN cell is detected, the UE can terminate the cell search based on the detection of the SSB (Yes in S113). In this case, the UE can obtain time and frequency synchronization for the TN cell based on the SSB and perform the initial access procedure for the TN cell.

[0143] The UE can obtain the PBCH, including the 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 MIB.

[0144] Alternatively, when no SSB is detected for a TN cell with higher priority (No in S113), the UE may (re)attempt to detect an SSB for an NTN cell that can be assumed / expected to have lower priority (S115). For example, when detection of an SSB for a TN cell fails, the UE may retry detection of an SSB for an NTN cell with lower priority. For example, when SSB detection using a receive beam shaped in the ground direction (where a TN cell may be located) fails, the UE may (re)attempt SSB detection by changing the direction of the receive beam to face the sky (where an NTN cell may be located) to perform a cell search for an NTN cell.

[0145] For example, a UE can attempt to detect an SSB for a high-priority TN cell for a given synchronization grid k. If the detection of an SSB for a TN cell fails for synchronization grid k, the UE can retry the detection of an SSB for the NTN cell for the synchronization grid k for which the detection of an SSB for a TN cell failed.

[0146] When the UE successfully detects an SSB for a TN cell, the UE can perform an initial access procedure for the TN cell based on the successfully detected SSB. Alternatively, when the detection of an SSB for a TN cell fails but the detection of an SSB for an NTN cell is successful in the attempt to detect an SSB for an NTN cell, the UE can perform an initial access procedure for the NTN cell.

[0147] Reference Figure 12 The UE can attempt to prioritize the detection of SSBs S121 that are expected / assumed to be associated with an NTN cell (a high-priority network cell). For example, the UE can attempt to detect SSBs by using a receive beam oriented towards the sky (where the NTN cell may be located) to prioritize cell search for the NTN cell. The UE can prioritize cell search for the NTN cell by using a receive beam oriented towards the sky.

[0148] Then, the UE can terminate cell search if an SSB for the NTN cell is detected (Yes in S123). In this case, the UE can obtain time and frequency synchronization of the NTN cell based on the SSB and perform the initial access procedure for the NTN cell.

[0149] Alternatively, when no SSB targeting a higher-priority NTN cell is detected (No in S123), the UE may (re)attempt to detect an SSB that can be assumed / expected to target a lower-priority TN cell (S125). For example, when detection of an SSB targeting an NTN cell fails, the UE may reattempt to detect an SSB targeting a lower-priority TN cell. For example, when SSB detection fails using a receive beam shaped in the sky direction (where the NTN cell may be located), the UE may change the receive beam to a receive beam shaped in the ground direction and reattempt to detect the SSB. When an SSB is detected using a receive beam shaped in the ground direction, the UE may assume / expect that the detected SSB is an SSB targeting a TN cell.

[0150] For example, a UE can attempt to detect an SSB for a high-priority NTN cell for a given synchronization grid k. If the detection of an SSB for an NTN cell fails for synchronization grid k, the UE can retry the detection of an SSB for a TN cell for the synchronization grid k for which the detection of an SSB for a TN cell failed.

[0151] The following section describes in detail the method for configuring / determining the priority between TN and NTN cells.

[0152] Figure 13 This is a diagram illustrating the method for configuring / determining priorities between TN and NTN cells.

[0153] The priority between the TN cell and the NTN cell can be determined / configured based on at least one of the following alternative schemes 1-1, 1-2, 1-3 or 1-4.

[0154] (1) Alternative Plan 1-1

[0155] Priority can be configured so that TN cells always have higher priority than NTN cells. In this case, the UE can always prioritize the detection of SSBs for TN cells, and when an SSB for a TN cell is detected, the UE can perform the initial access procedure based on the detected SSB. Alternatively, when the detection of an SSB for a TN cell fails, the UE can (re)attempt the detection of an SSB for an NTN cell.

[0156] (2) Alternative Plan 1-2

[0157] Priority can be configured so that NTN cells always have higher priority than TN cells. In this case, the UE can always prioritize detecting SSBs for NTN cells, and when an SSB for an NTN cell is detected, the UE can perform the initial access procedure for the NTN cell based on the detected SSB. Alternatively, when the detection of an SSB for an NTN cell fails, the UE can (re)attempt to detect an SSB for a TN cell.

[0158] (2) Alternative options 1-3

[0159] Priorities can be configured / determined based on various UE types (or communication types), applications, and / or requirements.

[0160] For example, such as Figure 13 As illustrated, the UE can support power-constrained (transmit / receive power) Low Power Wide Area (LPWA) or Reduced Capability (RedCAP) types, ultra-reliable low-latency communication (URLLC) types requiring sensitive latency, massive machine-type communication (mMTC) or Internet of Things (IoT) (or narrowband IoT) types requiring massive connectivity, and / or vehicle-to-everything (V2X) types with high mobility (e.g., communication between vehicles capable of high-speed travel or communication within a train). In this case, the network (or directly by the UE) can configure / determine the priority between the NTN and TN based on various types, requirements, applications, etc.

[0161] For example, for power-constrained UE types or communication types (such as LPWA or RedCap), priority can be determined / configured to prioritize TN cells over NTN cells. Alternatively, for URLLC UE types or communication types requiring sensitive latency requirements, priority can be determined / configured to prioritize TN cells over NTN cells.

[0162] Alternatively, for mMTC or IoT type UEs requiring large-scale connectivity, priority can be determined / configured to give NTN cells priority over TN cells. Alternatively, priority can be configured / determined to give NTN cells priority over TN cells for V2X type UEs with high mobility.

[0163] (4) Alternative options 1-4

[0164] Alternatively, the UE can directly determine / configure the priority between NTN and TN cells based on the surrounding environment or communication environment. For example, the UE can configure / determine the priority so that TN cells take precedence over NTN cells when the surrounding environment or communication environment is urban. Alternatively, when the surrounding environment or communication environment is rural, the UE can configure / determine the priority so that NTN cells take precedence over TN cells. For example, the UE can determine whether its location is urban or rural using GPS or other methods.

[0165] Alternatively, when it is determined that the UE is located on a highway based on GPS / area ID / moving speed, the priority can be configured to give priority to NTN cells over TN cells. Alternatively, the UE can be configured to give priority to NTN cells over TN cells when the UE's moving speed is equal to or greater than a certain threshold.

[0166] Figures 14 to 16 This diagram illustrates the method for a UE to perform cell search in a frequency band where NTN and TN cells coexist.

[0167] The UE can prioritize detecting SSBs for higher-priority network cells in NTN and TN cells within a synchronization grid. The UE can determine whether to additionally attempt to detect SSBs for lower-priority network cells within a synchronization grid where an SSB for a higher-priority network cell has already been detected. Specifically, when the UE fails to detect an SSB for a higher-priority network cell, the UE can additionally attempt to detect an SSB for a lower-priority network cell within the synchronization grid (Alternative 2-1). Alternatively, the UE can determine whether to (re)attempt to detect an SSB for a lower-priority cell based on information contained in the detected SSB for a higher-priority network cell (Alternative 2-3).

[0168] Alternatively, when both a high-priority network cell and an SSB for the high-priority network cell are detected for the synchronization grid, the UE can select / determine the network cell to be used for the initial access procedure from the two network cells based on the quality difference between the two detected SSBs (Alternative 2-2).

[0169] The above alternative option 2-1 is referred to Figure 14 Alternative option 2-2 is referenced. Figure 15 Alternative options 2-3 are for reference. Figure 16 Please provide a detailed explanation.

[0170] (1) Alternative Option 2-1 (Priority Only)

[0171] Alternative scheme 2-1 allows the UE to perform a cell search procedure for frequency bands where TN and NTN cells coexist, taking only priority into account. For example, the UE can attempt to detect SSBs for cell search by considering only the priorities of TN and NTN cells, and perform an initial access procedure on the detected SSBs.

[0172] Reference Figure 14 The UE can attempt to detect SSBs targeting higher-priority network cells in both NTN and TN cells (S141). For example, the UE can attempt to detect SSBs targeting higher-priority network cells in both NTN and TN cells within the synchronization grid k. When the UE successfully detects an SSB targeting a high-priority network cell in the synchronization grid k (as in S143), the UE can choose not to (re)attempt to detect SSBs targeting lower-priority network cells in the synchronization grid k. For example, when TN cells have higher priority among NTN and TN cells, the UE can prioritize detecting SSBs targeting TN cells in the synchronization grid k, and when the detection of such SSBs is successful, the UE can choose not to (re)attempt to detect SSBs targeting NTN cells in the synchronization grid k.

[0173] Alternatively, when no SSB for a high-priority network cell is detected in synchronization grid k (No in S143), the UE may (re)attempt to detect an SSB for a low-priority network cell in synchronization grid k (S145). For example, when TN cells have higher priority than NTN cells, the UE may prioritize detecting SSBs for TN cells in synchronization grid k, and when no SSB for TN cells is detected in synchronization grid k, the UE may (re)attempt to detect SSBs for NTN cells in synchronization grid k. For example, the UE may prioritize detecting SSBs for TN cells in synchronization grid k by using a ground-direction receiving beam, and when detection of an SSB for TN cells fails, it may (re)attempt to detect SSBs for NTN cells in synchronization grid k using a sky-direction receiving beam.

[0174] Alternatively, when the UE fails to detect an SSB for both high-priority and low-priority networks in synchronization grid k (i.e., fails to detect an SSB for both NTN and TN cells), the UE may retry detecting the SSB in the next synchronization grid (synchronization grid k+1) based on the priorities described above.

[0175] Then, the UE can perform the initial access procedure S147 based on the detected SSB. For example, when the high-priority network cell is a TN cell and an SSB for the TN cell is detected in the synchronization grid k, the UE can perform the initial access procedure for the TN cell based on the detected SSB for the TN cell. Alternatively, when the UE (re)attempts to detect an SSB for the NTN cell because no SSB for the TN cell is detected in the synchronization grid k, and when the UE detects an SSB for the NTN cell in the synchronization grid k, the UE can perform the initial access procedure based on the detected SSB for the NTN cell.

[0176] For example, a UE can be configured to have higher priority for TN cells within both NTN and TN cells. In this case, the UE can prioritize detecting SSBs for higher-priority TN cells in the synchronization grid k. When the UE successfully detects an SSB for a high-priority TN cell in the synchronization grid k, the UE can perform the initial access procedure for the TN cell based on the detected SSB. When the detection of an SSB for a TN cell is successful, the UE may not (re)attempt to detect an SSB for an NTN cell in the synchronization grid k.

[0177] (2) Alternative option 2-2 (priority + RSRP threshold)

[0178] Alternative scheme 2-2 involves a priority-based cell search process, and when an SSB is detected for both NTN and TN cells, the UE selects the cell for the initial access procedure from the NTN and TN cells based on the quality of the detected SSB and a second threshold.

[0179] For ease of explanation, the SSB for higher priority network cells in NTN and TN cells will be defined as the first SSB, and the SSB for lower priority network cells will be defined as the second SSB.

[0180] Reference Figure 15 The UE can attempt to detect SSBs for NTN and TN cells sequentially based on priority within the synchronization grid k (S151). That is, for the synchronization grid k, the UE can attempt to detect SSBs in order from network cells with higher priority to those with lower priority. For example, when a TN cell has a higher priority than an NTN cell, the UE can first attempt to detect the SSB for the TN cell (first SSB) within the synchronization grid k (using the receive beam for the ground direction), and then (re)attempt to detect the SSB for the NTN cell (second SSB).

[0181] For example, for a synchronization grid k, the UE can prioritize detecting the first SSB, which is an SSB for high-priority network cells, and when the first SSB is detected, it can (re)attempt to detect the second SSB, which is an SSB for low-priority network cells. In this case, for synchronization grid k, the UE can detect both the first and second SSBs. In other words, for this synchronization grid, the UE can detect not only SSBs for high-priority network cells but also SSBs for low-priority network cells.

[0182] Then, when both the first SSB and the second SSB are detected for a synchronization grid (as in S153), the UE can select a cell for the initial access procedure from high-priority and low-priority network cells based on the quality difference between the first and second SSBs and a first threshold (S155). This first threshold can be pre-configured using higher-layer network signals or physical layer signals, etc.

[0183] Specifically, when the quality of the second SSB is higher than (or exceeds) a first threshold than the quality of the first SSB, the UE can select a low-priority network cell as the cell for the initial access procedure, even if the network cell is a low-priority network cell. Conversely, when the quality of the second SSB is not higher than the first SSB by the threshold, the UE can select a higher-priority network cell as the cell for the initial access procedure based on priority. Then, the UE can perform the initial access procedure S157 for the selected network cell.

[0184] Here, the quality of the SSB can be the reference signal received power (RSRP) measured during SSB detection, and the first threshold can be pre-configured / pre-indicated as a threshold for the RSRP. For example, both the first and second SSBs can be detected within the synchronization grid k. In this case, when the quality of the second SSB is measured by the RSRP... low Subtract the mass of the first SSB from RSRP high The obtained value is equal to or greater than (or exceeds) the first threshold. (RSRP) low - RSRP high > When the UE selects a network cell with a lower priority as the cell for the initial access procedure, it can choose the cell with the lower priority. Conversely, when the quality RSRP is obtained from the second SSB, the UE can select the cell with the lower priority. low Subtract the mass RSRP of the first SSB high The obtained value is less than the first threshold. When a UE is in a certain situation, it can select a network cell with a higher priority as the cell for the initial access procedure.

[0185] For example, when a TN cell has a higher priority than an NTN cell and, for a synchronization grid, both a first SSB for the TN cell and a second SSB for the NTN cell are detected, the UE can select the 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 a first threshold. When the quality RSRP of the second SSB is used... low Subtract the mass of the first SSB from RSRP high The obtained value is equal to or greater than (or exceeds) the first threshold. (RSRP) low - RSRP high > When the UE selects an NTN cell as the cell for the initial access procedure, it performs the initial access procedure for the NTN cell based on the second SSB. Conversely, when the quality RSRP from the second SSB is used... low Subtract the mass RSRP of the first SSB high The obtained value is less than (or equal to or less than) the first threshold. (RSRP) low - RSRP high < When the UE selects an NTN cell as the cell for the initial access procedure, it performs the initial access procedure for the TN cell based on the first SSB.

[0186] Alternatively, when detecting SSBs for TN and NTN cells according to priority order, the UE may successfully detect only one of the SSBs for TN and NTN cells (No in S153). For example, in synchronization grid k, the UE may fail to detect the first SSB for a high-priority network cell but successfully detect the second SSB for a low-priority network cell. Alternatively, in synchronization grid k, the UE may fail to detect the second SSB after successfully detecting the first SSB. In this case, the UE may perform the initial access procedure S157 based on the detected SSB for the network cell. For example, if only the first SSB for the TN cell, which is a high-priority network cell, is detected, the UE may perform the initial access procedure for the TN cell based on the first SSB. Conversely, when only the detection of the second SSB is successful, the UE may perform the initial access procedure for the NTN cell, which has a low priority, based on the second SSB.

[0187] Alternatively, within synchronization grid k, the UE may be unable to detect SSBs for both high-priority and low-priority network cells. In this case, detection of SSBs for NTN and / or TN cells can be retried based on priority for synchronization grid k+1 (the next synchronization grid after synchronization grid k), as described above.

[0188] (3) Alternative options 2-3 (priority + instructions)

[0189] In alternative schemes 2-3, an attempt is made to detect SSBs for higher-priority network cells in the NTN and TN cell categories, and it can be determined whether to (re)attempt to detect SSBs for lower-priority network cells based on the information included in the detected SSBs.

[0190] Reference Figure 16 For the synchronization grid, the UE can detect the first SSB (Second Slot Bus) for a high-priority network cell (S161). For example, when a TN cell has high priority, the UE can detect the first SSB for the TN cell in the synchronization grid by using the ground-direction receive beam.

[0191] When the first SSB is detected, the UE can obtain indication information indicating the presence of a low-priority network cell and / or information about the second threshold RSRP from the detected first SSB. th Information such as the PBCH can be obtained from the detected first SSB, and indication information and a second threshold can be obtained from the Master Information Block (MIB) included in the PBCH. The UE can determine or identify whether the first SSB is for a TN cell or an NTN cell based on information detected from the MIB about the cell associated with the first SSB. For example, when a TN cell has high priority, the UE can obtain indication information about the presence or absence of an NTN cell from the first SSB.

[0192] Then, the UE can determine, based on the second threshold and the indication information included in the first SSB, whether it is necessary to (re)attempt to detect the second SSB for the lower priority network cell in the synchronization grid where the first SSB was detected, S163.

[0193] Specifically, when the indication information included in the first SSB indicates the presence of a low-priority network cell and the quality of the first SSB is less than (or equal to or less than) the threshold RSRP th At that time, for synchronization grid k, the UE can (re)attempt to detect the SSB in order to detect the second SSB for the low-priority network cell.

[0194] Conversely, when the quality of the first SSB is equal to or greater than (or exceeds) the threshold RSRP thEven when the indication information indicates the presence of a low-priority network cell, the UE may not attempt to detect a second SSB for the low-priority network cell in the synchronization grid k.

[0195] When it is determined that an attempt is made to detect a second SSB for a low-priority network cell and the detection of the second SSB is successful, the UE can determine whether to perform the initial access procedure S165 based on the first SSB or the second SSB. For example, when the quality of the second SSB is equal to or higher than a second threshold, the UE can perform the initial access procedure for the low-priority network cell based on the second SSB. Alternatively, as in Alternative Scheme 2-2 above, when the quality of the second SSB is equal to or greater than the first SSB than the first threshold, the initial access procedure can be performed for the lower-priority network cell instead of the higher-priority network cell.

[0196] Conversely, when the quality of the second SSB is less than the second threshold, the UE can perform an initial access procedure for a higher-priority network cell based on priority. Alternatively, when the quality of both the first and second SSBs is less than the second threshold, the UE may not perform an initial access procedure and may retry detecting the first and / or second SSB in synchronization grid k+1.

[0197] For example, a TN cell can have a higher priority than an NTN cell. In this case, for a synchronization grid k, the UE can prioritize attempting to detect the first SSB for the TN cell. In other words, in synchronization grid k, the UE can prioritize attempting to detect the first SSB for the TN cell by using a ground-direction receiving beam. When the UE detects the first SSB, the UE can determine whether to additionally attempt to detect a second SSB for the NTN cell in synchronization grid k based on a second threshold and indication information included in the SSB. 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 less than) the second threshold, the UE can nearby attempt to detect the second SSB for the NTN cell in synchronization grid k. For example, in synchronization grid k, the UE can (re)attempt to detect the second SSB for the NTN cell by using a sky-direction receiving beam. Then, when a second SSB with a measurement quality equal to or greater than (or exceeding) the second threshold is detected, the UE can perform an initial access procedure for the NTN cell based on the second SSB. Conversely, when the quality of the second SSB is less than (or equal to or less than) the second threshold, the UE can perform an initial access procedure for the TN cell based on the first SSB according to priority. Alternatively, based on the fact that the quality of the first and second SSBs is less than the second threshold, the UE can sequentially attempt to detect SSBs for the NTN cell in the next synchronization grid (synchronization grid k+1) according to priority, without performing an initial access procedure based on the SSB detected in synchronization grid k.

[0198] Alternatively, when the first SSB is not detected in synchronization grid k, the UE may attempt to detect the first SSB in the next synchronization grid k+1. For example, the difference between Alternative 2-3 and Alternative 2-1 and / or Alternative 2-2 is that when the detection of the first SSB for a higher priority network cell fails for a synchronization grid pair, the former does not attempt to detect additional SSBs for lower priority network cells.

[0199] In this way, in a frequency band where TN and NTN cells coexist, the UE can explicitly determine which network's cell search should be prioritized based on priority. That is, when a TN cell has priority, the UE can quickly and efficiently search for TN cells using a receive beam for the ground direction. Alternatively, when an NTN cell has priority, the UE can quickly and efficiently search for NTN cells using a receive beam for the sky direction. Based on this indication information, the UE can easily identify the coexistence of NTN and TN cells in the frequency band and can explicitly determine whether a cell search for the lower-priority network cell is necessary based on a second threshold. When an SSB is detected for both TN and NTN cells, the UE can explicitly and effectively determine which network's cell should be used for the initial access procedure based on a pre-configured first threshold.

[0200] In some implementations of this disclosure, the transmission of a signal / channel by the UE or BS into a transmit beam can be represented as the transmission of the signal / channel into a spatial domain transmission filter. In some implementations of this disclosure, the reception of a signal / channel by the UE or BS in a receive beam can be represented as the reception of the signal / channel using a spatial domain receive filter. For example, transmission using the same transmit beam can mean transmission using the same spatial domain transmit filter, and reception using the same receive beam can mean reception using the same spatial domain receive filter.

[0201] Here, the wireless communication technologies implemented in the wireless devices XXX and YYY of this disclosure may include LTE, NR, and 6G, as well as narrowband Internet of Things (IoT) for low-power communication. In this case, for example, NB-IoT technology may be an example of low-power wide-area network (LPWAN) technology and may be implemented using standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the names mentioned above. Additionally or alternatively, the wireless communication technologies implemented in the wireless devices XXX and YYY of this disclosure may perform communication based on LTE-M technology. In this case, for example, LTE-M technology may be an example of LPWAN technology and may be referred to by various names such as enhanced machine-type communication (eMTC). For example, LTE-M technology may be implemented by at least one of various standards, including but not limited to 1) LTE Cat 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE machine-type communication, and / or 7) LTE M, and is not limited to the names mentioned above. Additionally or alternatively, the wireless communication technologies implemented in the wireless devices XXX and YYY of this disclosure may include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low-power communication, and are not limited to the aforementioned names. For example, ZigBee technology may be based on various standards such as IEEE 802.15.4 to generate Personal Area Networks (PANs) for small / low-power digital communication, and may be referred to by various names.

[0202] The embodiments of this disclosure described above are combinations of the elements and features of this disclosure. Unless otherwise stated, elements or features may be considered optional. Each element or feature may be practiced without combination with other elements or features. Furthermore, embodiments of this disclosure may be constructed by combining portions of elements and / or features. The order of operations described in the embodiments of this disclosure may be rearranged. Some constructions of any embodiment may be included in another embodiment and may be replaced by corresponding constructions of another embodiment. It will be apparent to those skilled in the art that claims not expressly referenced in each other in the appended claims may be presented as combinations of embodiments of this disclosure or may be included as new claims by subsequent amendments after filing.

[0203] In embodiments of this disclosure, the description focuses on the data transmission and reception relationship between the BS and the UE. This transmission and reception relationship is similarly extended to signal transmission and reception between the UE and a repeater, or between the BS and a repeater. In this disclosure, specific operations described as being performed by the BS can be performed by upper-layer nodes of the BS. That is, it is apparent that in a network consisting of multiple network nodes including the BS, various operations performed for communication with the UE can be performed by the BS or network nodes other than the BS. The term "BS" can be replaced by the terms "fixed station," "node B," "evolved node B (eNodeB or eNB)," or "access point." The term "terminal" can be replaced by the terms "UE," "mobile station (MS)," "mobile subscriber station (MSS)," etc.

[0204] The embodiments of this disclosure can be implemented by various means, such as hardware, firmware, software, or a combination thereof. In a hardware configuration, the embodiments of this disclosure can be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSDPs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[0205] In firmware or software configurations, embodiments of this disclosure can be implemented in the form of modules, processes, functions, etc. Software code can be stored in memory units and executed by a processor. The memory units may be located internally or externally to the processor and can send data to and receive data from the processor via various known means.

[0206] It will be apparent to those skilled in the art that this disclosure may be practiced in other specific forms without departing from its characteristics. Therefore, the detailed description should not be construed as restrictive in any way, but rather as illustrative. The scope of this disclosure should be determined by a reasonable interpretation of the appended claims, and all variations within the equivalent scope of this disclosure are included within its scope.

[0207] Industrial applicability

[0208] The embodiments of this disclosure described above can be applied to various mobile communication systems.

Claims

1. A method for a user equipment (UE) to receive downlink signals in a wireless communication system, the method comprising the following steps: Attempt to detect synchronization signal block SSB in the first frequency band supporting TN cells for terrestrial networks and NTN cells for non-terrestrial networks; as well as The initial access process is performed based on the detected SSBs. Specifically, based on the priorities configured for the TN and NTN cells, the step of attempting to detect the SSB is performed on the cell with the higher priority among the TN and NTN cells.

2. The method according to claim 1, wherein, Based on the higher priority of the TN cell, the step of attempting to detect the SSB is performed in the order of the TN cell to the NTN cell, and Based on the detection of both a first SSB for the TN cell and a second SSB for the NTN cell, and based on a first threshold and priority for the quality configuration of the SSB, the initial access procedure is performed for one of the TN and NTN cells.

3. The method according to claim 2, wherein, Based on the fact that the quality of the second SSB is higher than the quality of the first SSB by the first threshold, even if the TN has a higher priority, the NTN cell is still identified as one of the cells.

4. The method according to claim 2, wherein, Based on the fact that the quality of the first SSB is not lower than the quality of the second SSB by the first threshold, the TN cell with the higher priority is determined as the cell.

5. The method according to claim 1, wherein, Based on the detection of an SSB including indication information indicating the presence of a low-priority cell in the SSB and a second threshold, and the quality of the SSB being lower than the second threshold, the UE attempts to detect the SSB for the low-priority cell among the TN cell and the NTN cell.

6. The method according to claim 1, wherein, The priority is configured based on at least one of the UE's type, mobility, communication environment, and service requirements.

7. The method according to claim 6, wherein, Based on whether the UE is of the massive machine-type communication (mMTC), vehicle-to-everything (V2X), or narrowband Internet of Things (NB-IoT) type, the NTN is configured to have a higher priority than the TN.

8. A user equipment (UE) for receiving downlink signals in a wireless communication system, the UE comprising: At least one transceiver; At least one processor; as well as At least one computer memory, operatively connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform an operation. The operation includes: attempting to detect Synchronization Signal Blocks (SSBs) in a first frequency band supporting TN (Terrestrial Network) cells and NTN (Non-Terrestrial Network) cells, and performing an initial access procedure based on the detected SSBs. Specifically, based on the priorities configured for the TN and NTN cells, the operation of attempting to detect the SSB is preferentially performed on the cell with the higher priority among the TN and NTN cells.

9. A processing apparatus for receiving downlink signals in a wireless communication system, the processing apparatus comprising: At least one processor; as well as At least one computer memory, operatively connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform an operation. The operation includes: attempting to detect Synchronization Signal Blocks (SSBs) in a first frequency band supporting TN (Terrestrial Network) cells and NTN (Non-Terrestrial Network) cells, and performing an initial access procedure based on the detected SSBs. Specifically, based on the priorities configured for the TN and NTN cells, the operation of attempting to detect the SSB is preferentially performed on the cell with the higher priority among the TN and NTN cells.

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