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

Abstract

A UE may receive a TCI configuration for each of one or more CORESETs. The TCI configuration may include TCI states, and each of the TCI states may include QCL information about a downlink reference signal. The UE may determine a first TCI state for a first time period, determine a first CORESET for which the first TCI state is configured, and perform PDCCH monitoring on the basis of the first TCI state for the first CORESET within the first time period.

Description

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

[0001] This specification relates to wireless communication systems.

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

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

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

[0005] The technical tasks to be achieved by this specification are not limited to the technical tasks mentioned above, and other technical tasks not mentioned will be clearly understood by those skilled in the art related to this specification from the detailed description below.

[0006] In one aspect of the present specification, a method for receiving a downlink signal by a user equipment (UE) in a wireless communication system supporting a non-terrestrial network (NTN) is provided. The method may include: receiving a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; determining a first TCI state for a first time period; determining a first CORESET for which the first TCI state is set; and performing physical downlink control channel (PDCCH) monitoring for the first CORESET based on the first TCI state within the first time period.

[0007] In another aspect of the present disclosure, a user equipment (UE) for receiving a downlink signal in a wireless communication system supporting a non-terrestrial network (NTN) is provided. The UE comprises: at least one transceiver; at least one processor; and at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations comprising: receiving a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; determining a first TCI state for a first time period; determining a first CORESET for which the first TCI state is set; And may include performing physical downlink control channel (PDCCH) monitoring based on the first TCI-state for the first CORESET within the first time period.

[0008] In another aspect of the present disclosure, a processing device is provided. The processing device comprises: at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations including: receiving a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; determining a first TCI state for a first time period; determining a first CORESET for which the first TCI state is set; and performing physical downlink control channel (PDCCH) monitoring for the first CORESET based on the first TCI state within the first time period.

[0009] In another aspect of the present disclosure, a computer-readable storage medium is provided. The storage medium stores at least one program code comprising instructions that, when executed, cause at least one processor to perform operations, the operations including: receiving a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; determining a first TCI state for a first time period; determining a first CORESET for which the first TCI state is set; and performing physical downlink control channel (PDCCH) monitoring for the first CORESET based on the first TCI state within the first time period.

[0010] In another aspect of the present disclosure, a method for transmitting a downlink signal by a base station in a wireless communication system supporting a non-terrestrial network (NTN) is provided. The method may include: transmitting a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; determining a first TCI state for a first time period; determining a first CORESET for which the first TCI state is set; and performing a physical downlink control channel (PDCCH) transmission based on the first TCI state for the first CORESET within the first time period.

[0011] In another aspect of the present disclosure, a base station for transmitting a downlink signal in a wireless communication system supporting a non-terrestrial network (NTN) is provided. The base station comprises: at least one transceiver; at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations comprising: transmitting a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; determining a first TCI state for a first time period; determining a first CORESET for which the first TCI state is set; And may include performing a physical downlink control channel (PDCCH) transmission based on the first TCI-state for the first CORESET within the first time period.

[0012] In another aspect of the present disclosure, a processing device is provided. The processing device comprises: at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations including: transmitting a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; determining a first TCI state for a first time period; determining a first CORESET for which the first TCI state is set; and performing a physical downlink control channel (PDCCH) transmission for the first CORESET based on the first TCI state within the first time period.

[0013] In another aspect of the present disclosure, a computer-readable storage medium is provided. The storage medium stores at least one program code comprising instructions that, when executed, cause at least one processor to perform operations, the operations including: transmitting a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; determining a first TCI state for a first time period; determining a first CORESET for which the first TCI state is set; and performing a physical downlink control channel (PDCCH) transmission for the first CORESET based on the first TCI state within the first time period.

[0014] In each aspect of this specification, the first TCI-state for the first time period may be determined based on a predetermined TCI transition pattern.

[0015] In each aspect of this specification, settings regarding the predetermined TCI transition pattern can be provided to the user equipment by the base station.

[0016] In each aspect of the present specification, the method or the operations may: perform PDCCH monitoring or PDCCH transmission based on the first TCI-state for / through all CORESETs set for the cell, based on the absence of a CORESET for which the first TCI-state is set within the first time period, of the PDCCH monitoring time of the associated search space set.

[0017] In each aspect of the present specification, performing PDCCH monitoring or PDCCH transmission for / through the CORESET based on the first TCI-state may include: performing PDCCH monitoring or PDCCH transmission for a search space set associated with the CORESET using a QCL relationship between a downlink reference signal for the first TCI-state and a demodulation reference signal of the PDCCH.

[0018] The above problem solving means are only some of the examples of this specification, and various examples reflecting the technical features of this specification can be derived and understood by a person having ordinary knowledge in the relevant technical field based on the detailed description below.

[0019] According to some implementations of this specification, wireless communication signals can be efficiently transmitted and received via airborne platforms or space. This can increase the overall throughput of a wireless communication system.

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

[0021] According to some implementations of this specification, UE receive beams (and / or BS transmit beams) can be reliably changed in communication systems with large propagation delays.

[0022] According to some implementations of this specification, the time required for UE receive beam (and / or BS transmit beam) switching can be reduced. Therefore, according to some implementations of this specification, beam switching is possible with low delay.

[0023] According to some implementations of this specification, beam switching can be directed with little signaling overhead.

[0024] The effects according to this specification are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art related to this specification from the detailed description below.

[0025] To aid in understanding implementations of this specification, the accompanying drawings, which are included as part of the detailed description, provide examples of implementations of this specification and, together with the detailed description, illustrate implementations of this specification:

[0026] FIG. 1 is a block diagram illustrating examples of communication devices capable of performing a method according to the present specification;

[0027] Figure 2 illustrates an example of a frame structure available in a 3GPP-based wireless communication system;

[0028] Figure 3 illustrates a resource grid of slots;

[0029] Figure 4 illustrates PDCCH monitoring time(s);

[0030] Figure 5 illustrates multi-beam operation in a 3GPP based system;

[0031] FIG. 6 illustrates an example of transmission of synchronization signal (SS) / physical broadcast channel (PBCH) blocks (SS / PBCH blocks) on a cell;

[0032] FIG. 7 and FIG. 8 are drawings illustrating the multi-beam operation of PDCCH;

[0033] Figures 9 to 11 are illustrated to explain the multi-beam operation of PDSCH; 9 is

[0034] Figure 12 illustrates a non-terrestrial network (NTN) structure;

[0035] Figure 13 illustrates a non-terrestrial network (NTN) deployment scenario;

[0036] Figure 14 illustrates beam switching for a satellite with multi-beam operation;

[0037] FIG. 15 is a diagram illustrating a problem when applying a transmission configuration indicator (TCI)-state change based on a conventional medium access control (MAC) control element (CE) and / or downlink control information (DCI) to NTN;

[0038] FIG. 16 and FIG. 17 illustrate a flow of two-level multi-beam operation for PDCCH according to some implementations of the present specification;

[0039] FIG. 18 illustrates TCI-state changes according to 2-level multi-beam operation for PDCCH of the present specification;

[0040] FIG. 19 is a diagram illustrating the concept of PDCCH monitoring adaptation according to some implementations of the present specification;

[0041] Figure 20 illustrates autonomous CORESET switching according to some implementations of this specification;

[0042] Figure 21 illustrates autonomous search space switching according to some implementations of this specification;

[0043] FIG. 22 illustrates a flow of downlink signal reception in a UE according to some implementations of the present specification;

[0044] Figure 23 illustrates the flow of downlink signal transmission in a BS according to some implementations of the present specification.

[0045] Hereinafter, implementations according to this specification will be described in detail with reference to the attached drawings. The detailed description provided below, together with the attached drawings, is intended to describe exemplary implementations of this specification and is not intended to represent the only possible implementations of this specification. The detailed description below includes specific details to provide a thorough understanding of this specification. However, one of ordinary skill in the art will appreciate that this specification may be practiced without these specific details.

[0046] In some cases, to avoid ambiguity in the concepts of this specification, known structures and devices may be omitted or illustrated in block diagram form focusing on the core functions of each structure and device. Furthermore, identical components are described using the same drawing reference numerals throughout this specification.

[0047] The techniques, devices, and systems described below can be applied to various wireless multiple access systems.

[0048] For convenience of explanation, the following description is based on a 3rd Generation Partnership Project (3GPP)-based communication system. However, the technical features of this specification are not limited thereto. For example, although the detailed description below is based on 3GPP (3rd Generation Partnership Project) LTE or 5G technology, some implementations of this specification are applicable to any other mobile communication system and systems to be introduced in the future (e.g., 6G), except for those specific to 3GPP LTE / 5G.

[0049] For terms and technologies used in this specification that are not specifically explained, refer to 3GPP-based standard documents, for example, 3GPP TS 23.304, 3GPP TS 23.285, 3GPP TS 23.287, 3GPP TS 24.587, 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.300, 3GPP TS 36.321, 3GPP 36.322, 3GPP TS 36.323, 3GPP TS and 3GPP TS 36.331, 3GPP TS 37.213, 3GPP TS 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.214, 3GPP TS 38.300, 3GPP TS 38.321, 3GPP TS 38.322, 3GPP TS 38.323, and 3GPP TS 38.331.

[0050] In the examples of this specification described below, the expression "assumes" that a device "assumes" that the entity transmitting the channel transmits the channel in a manner consistent with the "assume." The entity receiving the channel may mean that, under the assumption that the channel was transmitted in a manner consistent with the "assume," the entity receiving the channel receives or decodes the channel in a manner consistent with the "assume."

[0051] In this specification, UE may be fixed or mobile, and includes various devices that communicate with a BS (base station, BS) to transmit and / or receive user data and / or various control information. UE may be referred to as (Terminal Equipment), MS (Mobile Station), MT (Mobile Terminal), UT (User Terminal), etc. In addition, in this specification, BS generally refers to a fixed station that communicates with UE and / or other BSs, and exchanges various data and control information by communicating with UE and other BSs. BS may be referred to by other terms such as ABS (Advanced Base Station), NB (Node-B), eNB (evolved-NodeB), gNB, BTS (Base Transceiver System), Access Point, PS (Processing Server), etc. For convenience of explanation, base stations are collectively referred to as BSs regardless of the type or version of communication technology.

[0052] In this specification, a node refers to a fixed point capable of transmitting and receiving wireless signals by communicating with a UE. Various types of BSs can be used as nodes, regardless of their designation. Each node is equipped with at least one antenna. The antenna may refer to a physical antenna, an antenna port, a virtual antenna, or an antenna group. A node is also referred to as a point.

[0053] Meanwhile, 3GPP-based communication systems use the concept of cells to manage wireless resources. Cells associated with wireless resources are distinct from cells within a geographic area. A "cell" within a geographic area can be understood as the coverage within which a node can provide services using a carrier, while a "cell" within a wireless resource is associated with a bandwidth (BW), which is the frequency range configured by the carrier. Downlink coverage, the range within which a node can transmit valid signals, and uplink coverage, the range within which a node can receive valid signals from a UE, depend on the carrier carrying the signals. Therefore, the coverage of a node is often associated with the coverage of the "cell" within which the wireless resources are used. Therefore, the term "cell" can sometimes refer to the coverage of a service provided by a node, sometimes to a wireless resource, and sometimes to the range within which a signal using the wireless resource can reach with effective intensity.

[0054] A "cell" associated with wireless resources can be defined as a combination of downlink resources (DL resources) and uplink resources (UL resources), i.e., a combination of a DL component carrier (CC) and an UL CC. A cell can be configured with only DL resources or a combination of DL resources and UL resources. When carrier aggregation is supported, the linkage between the carrier frequency of the DL resources (or DL ​​CC) and the carrier frequency of the UL resources (or UL CC) can be indicated by system information. Here, the carrier frequency can be the same as or different from the center frequency of each cell or CC.

[0055] In a wireless communication system, a UE receives information from a base station (BS) via the downlink (DL), and the UE transmits information to the base station via the uplink (UL). The information transmitted and / or received by the BS and UE includes data and various control information, and various physical channels exist depending on the type and purpose of the information they transmit and / or receive.

[0056] 3GPP-based communication standards define downlink physical channels corresponding to resource elements that carry information originating from higher layers, and downlink physical signals corresponding to resource elements that are used by the physical layer but do not carry information originating from higher layers. For example, the physical downlink shared channel (PDSCH), physical broadcast channel (PBCH), and physical downlink control channel (PDCCH) are defined as downlink physical channels, and reference signals and synchronization signals are defined as downlink physical signals. A reference signal (RS), also referred to as a pilot, refers to a signal with a predefined special waveform that is known to the BS and UE. For example, the demodulation reference signal (DMRS) and the channel state information RS (CSI-RS) are defined as downlink reference signals. 3GPP-based communication standards define uplink physical channels corresponding to resource elements that carry information originating from higher layers, and uplink physical signals corresponding to resource elements that are used by the physical layer but do not carry information originating from higher layers.For example, a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and a physical random access channel (PRACH) are defined as uplink physical channels, and a demodulation reference signal (DMRS) for uplink control / data signals and a sounding reference signal (SRS) used for uplink channel measurement are defined.

[0057] In this specification, PDCCH refers to a set of time-frequency resources (e.g., resource elements (REs)) that carry downlink control information (DCI), and PDSCH refers to a set of time-frequency resources that carry downlink data. In addition, PUCCH, PUSCH, and PRACH refer to sets of time-frequency resources that carry uplink control information (UCI), uplink data, and random access preamble, respectively (respectively). Hereinafter, the expression that a UE / BS transmits / receives a PUCCH / PUSCH / PRACH is used with the same meaning as that UCI / uplink data / random access preamble are transmitted / received on or through the PUCCH / PUSCH / PRACH, respectively. Additionally, the expression that BS / UE transmits / receives PBCH / PDCCH / PDSCH is used with the same meaning as transmitting / receiving broadcast information / DCI / downlink data on or through PBCH / PDCCH / PDSCH, respectively.

[0058] In this specification, radio resources (e.g., time-frequency resources) scheduled or configured by the BS to the UE for transmission or reception of PUCCH / PUSCH / PDSCH are also referred to as PUCCH / PUSCH / PDSCH resources.

[0059] Since a communication device receives physical channels and / or physical signals in the form of radio signals on a cell, it cannot selectively receive only radio signals containing only a specific physical channel or a specific physical signal through a radio frequency (RF) receiver, nor can it selectively receive only radio signals excluding only a specific physical channel or a specific physical signal through an RF receiver. In actual operation, the communication device first receives radio signals on a cell through an RF receiver, converts the radio signals, which are RF band signals, into baseband signals, and decodes the physical signals and / or physical channels within the baseband signals using one or more processors. Therefore, in some implementations of the present specification, not receiving a physical signal and / or a physical channel may not actually mean that the communication device does not receive radio signals containing the physical signal and / or physical channel, but rather does not attempt to recover the physical signal and / or physical channel from the radio signals, for example, does not attempt to decode the physical signal and / or the physical channel.

[0060] The communication system applicable to this specification includes a wireless device, a base station (BS), and a network. Here, a wireless device may refer to a device that performs communication using wireless access technology (e.g., 5G NR (New RAT), LTE (e.g., E-UTRA), WiFi, and 6G to be introduced in the future).

[0061] Although not limited thereto, wireless devices may include robots, vehicles, XR (eXtended Reality) devices, handheld devices, home appliances, IoT (Internet of Things) devices, and AI devices / servers. For example, BSs and networks may also be implemented as wireless devices, and a specific wireless device may act as a BS / network node to other wireless devices.

[0062] Wireless devices can connect to a network via a base station (BS). Wireless devices can incorporate artificial intelligence (AI) technology, and can connect to AI servers via the network. Wireless devices can communicate with each other via the base station / network, but they can also communicate directly (e.g., sidelink communication) without going through the base station / network.

[0063] Wireless communication / connection can be established between a wireless device and a BS, between BSs, and / or between wireless devices. Here, the wireless communication / connection can be uplink / downlink communication (UL / DL) and sidelink communication (SL) (or D2D communication) through various wireless access technologies (e.g., 5G NR). Through the wireless communication / connection (UL / DL, SL), the wireless device and the BS / wireless device can transmit / receive wireless signals to / from each other. To this end, at least some of various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes can be performed based on various proposals of this specification.

[0064] FIG. 1 is a block diagram illustrating examples of communication devices capable of performing a method according to the present specification. Referring to FIG. 1, a first wireless device (100) and a second wireless device (200) can transmit and / or receive wireless signals via various wireless access technologies. Here, {the first wireless device (100), the second wireless device (200)} may be wireless devices included in a communication system.

[0065] Each of the first wireless device (100) and the second wireless device (200) includes one or more processors (102, 202) and one or more memories (104, 204), and may further include one or more transceivers (106, 206) and / or one or more antennas (108). The processors (102, 202) control the memories (104, 204) and / or the transceivers (106, 206), and may be configured to implement the functions, procedures, and / or methods described / suggested below. For example, the processors (102, 202) may process information in the memories (104, 204) to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceivers (106, 206). In addition, the processor (102, 202) may receive a wireless signal including second information / signal through the transceiver (106, 206), and then store information obtained from signal processing of the second information / signal in the memory (104, 204). The memory (104, 204) may be connected to the processor (102, 202) and may store various information related to the operation of the processor (102, 202). For example, the memory (104, 204) may perform some or all of the processes controlled by the processor (102, 202), or store software code including commands for performing the procedures and / or methods described / proposed below. Here, the processor (102, 202) and the memory (104, 204) may be part of a communication modem / circuit / chip designed to implement wireless communication technology. A transceiver (106, 206) may be connected to a processor (102, 202) and may transmit and / or receive wireless signals via one or more antennas (108, 208). The transceiver (106, 206) may include a transmitter and / or a receiver.

[0066] Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and a service data adaptation protocol (SDAP) layer). One or more processors (102, 202) may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs) in accordance with the functions, procedures, proposals, and / or methods disclosed in this specification. One or more processors (102, 202) may generate messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed in this specification. One or more processors (102, 202) may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed in this specification, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) may receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed in this specification.

[0067] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the functions, procedures, proposals, and / or methods disclosed in this specification may be included in one or more processors (102, 202) or stored in one or more memories (104, 204) and executed by one or more processors (102, 202). The functions, procedures, proposals, and / or methods disclosed in this specification may be implemented using firmware or software in the form of codes, instructions, and / or sets of instructions.

[0068] One or more memories (104, 204) may be connected to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (104, 204) may be located internally and / or externally to one or more processors (102, 202). Additionally, one or more memories (104, 204) may be connected to one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0069] One or more transceivers (106, 206) may transmit / receive user data, control information, wireless signals / channels, etc., referred to in the methods and / or flowcharts of this specification, to / from one or more other devices. Furthermore, one or more processors (102, 202) may control one or more transceivers (106, 206) to transmit / receive user data, control information, or wireless signals to / from one or more other devices. Furthermore, one or more transceivers (106, 206) may be connected to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and / or receive user data, control information, wireless signals / channels, etc., referred to in the functions, procedures, proposals, methods, and / or flowcharts of this specification, via one or more antennas (108, 208). In this specification, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) may convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals / channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or a filter.

[0070] In this specification, at least one memory (104, 204) can store instructions or programs, which, when executed, cause at least one processor (102, 202) operably connected to the at least one memory to perform operations according to some embodiments or implementations of the present specification.

[0071] In this specification, a computer-readable (non-transitory) storage medium can store at least one instruction or computer program, which when executed by at least one processor causes the at least one processor to perform operations according to some embodiments or implementations of the present specification.

[0072] Figure 2 illustrates an example of a frame structure available in a 3GPP-based wireless communication system.

[0073] The structure of the frame in Fig. 2 is only an example, and the number of subframes, the number of slots, and the number of symbols in the frame can be varied. In some wireless communication systems, OFDM numerologies (e.g., subcarrier spacing (SCS)) may be set differently between multiple cells aggregated to a single UE. Accordingly, the (absolute time) duration of a time resource (e.g., subframe, slot, or transmission time interval (TTI)) composed of the same number of symbols may be set differently between the aggregated cells. Here, the symbol may include an OFDM symbol (or a cyclic prefix - orthogonal frequency division multiplexing (CP-OFDM) symbol), an SC-FDMA symbol (or a discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbol). In this specification, the terms symbol, OFDM-based symbol, OFDM symbol, CP-OFDM symbol and DFT-s-OFDM symbol may be interchangeable.

[0074] Referring to Figure 2, uplink and downlink transmissions are organized into frames. Each frame is T f = (△f max *N f / 100)*T c = 10 ms duration, where T is the basic time unit. c = 1 / (△f max *N f ) and △f max = 480*10 3 Hz, and N f =4096. For reference, the sampling time T s = 1 / (△f ref *Nf,ref ) and △f ref = 15*10 3 Hz, and N f,ref =2048. T s Wow T c is a constant κ = T s / T c = 64 relationship. A frame consists of 10 subframes, and the duration of a single subframe is T. sf is 1ms. Subframes are further divided into slots, and the number of slots in a subframe depends on the subcarrier spacing. Each slot is divided into N slots based on a cyclic prefix (CP). slot symb It can be composed of symbols. For example, in some scenarios, in the case of normal CP, each slot consists of 14 OFDM symbols, and in the case of extended CP, each slot consists of 12 OFDM symbols. The numerology is exponentially scalable with subcarrier spacing △f = 2. u *Depends on 15 kHz. The following table shows the subcarrier spacing for regular CP △f = 2. u *Number of OFDM symbols per slot at 15 kHz (N) slot symb ), number of slots per frame (N frame,u slot ) and the number of slots per subframe (N subframe,u slot ) is shown.

[0075]

[0076] The following table shows the subcarrier spacing for extended CP △f = 2. u *Indicates the number of OFDM symbols per slot, the number of slots per frame, and the number of slots per subframe at 15 kHz.

[0077]

[0078] For a subcarrier spacing setting u, slots are n in increasing order within a subframe. u s ∈ {0, ..., nsubframe,u slot - 1} and n in increasing order within the frame u s,f ∈ {0, ..., n frame,u slot - Numbered as 1}.

[0079] Hereinafter, implementations of this specification are described by referring to the minimum unit of time for scheduling uplink, downlink, and sidelink transmissions as a slot. However, depending on the wireless communication system, the minimum unit of time for scheduling may be referred to by a different term. For example, in an LTE-based system, the minimum unit of time for scheduling transmissions is referred to as a subframe or a transmission time interval (TTI), whereas in an NR-based system, the minimum unit of time for scheduling is referred to as a slot.

[0080] Figure 3 illustrates a resource grid of slots. A slot is a multiple (e.g., N) in the time domain. slot symb ) contains symbols of each numeral (e.g., subcarrier spacing) and carrier, a common resource block (CRB)N indicated by higher layer signaling (e.g., radio resource control (RRC) signaling). start,u grid Starting from,N size,u grid,x *N RB sc Dog subcarriers and N subframe,u symb A resource grid of OFDM symbols is defined, where N size,u grid,xis the number of resource blocks (RBs) in the resource grid, and the subscript x is DL for downlink and UL for uplink. N RB sc is the number of subcarriers per RB, and in 3GPP-based wireless communication systems, N RB sc is typically 12. For a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL), there is one resource grid. The carrier bandwidth N for subcarrier spacing configuration u size,u grid is given to the UE by higher layer parameters (e.g., RRC parameters) from the network. Each element in the resource grid for antenna port p and subcarrier spacing configuration u is called a resource element (RE), and one complex-valued symbol can be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index l indicating the symbol position relative to a reference point in the time domain. RBs can be classified into common resource blocks (CRBs) and physical resource blocks (PRBs). CRBs are numbered upwards from 0 in the frequency domain for subcarrier spacing configuration u. The center of subcarrier 0 of CRB 0 for subcarrier spacing configuration u coincides with 'point A', which is a common reference point for resource block grids. PRBs for subcarrier spacing configuration u are defined in a bandwidth part (BWP), numbered from 0 to N. size,u BWP,i -1, where i is the number of the bandwidth part. Common resource block n u CRB and bandwidth part i within physical resource block n PRB The relationship between the two is as follows: nu PRB = n u CRB +N start,u BWP,i , here N start,u BWP,i is a common resource block (BRB) whose bandwidth part starts relative to CRB 0. A BWP comprises multiple contiguous RBs in the frequency domain. For example, a BWP may be a given numeral u within a BWP i on a given carrier. i A subset of contiguous CRBs defined for a carrier. A carrier may contain up to N (e.g., 5) BWPs. A UE may be configured to have one or more BWPs on a given component carrier. Data communication is performed through the activated BWPs, and only a predetermined number (e.g., 1) of BWPs configured for the UE may be activated on the carrier.

[0081] Figure 4 illustrates PDCCH monitoring time(s). Figure 4 illustrates PDCCH monitoring time(s) according to the search space when the PDCCH monitoring period is 10 slots, the PDCCH monitoring offset is 2 slots, the search space duration is 3 slots, the PDCCH monitoring pattern is '10000001000000', and the associated CORESET duration is 2 symbols.

[0082] In a 3GPP-based system, a control resource set (CORESET), which is a set of time-frequency resources for which a UE can monitor PDCCHs, may be defined and / or configured. One or more CORESETs may be configured for each downlink (DL) BWP configured for the UE within a serving cell. A CORESET consists of a set of physical resource blocks (PRBs) with a duration of one to three OFDM symbols. The PRBs constituting the CORESET and the CORESET duration may be provided to the UE via higher layer (e.g., RRC) signaling. Within the configured CORESET(s), a set of PDCCH candidates is monitored according to the corresponding search space sets. In this specification, monitoring imply decoding (aka blind decoding) each PDCCH candidate according to the monitored DCI formats. A master information block (MIB) on the PBCH provides the UE with parameters (e.g., CORESET#0 configuration) for monitoring the PDCCH for scheduling the PDSCH carrying the system information block 1 (SIB1). The PBCH may also indicate that there is no associated SIB1, in which case the UE may be instructed on a frequency range in which it can assume that there is no SSB associated with SIB1, as well as other frequencies to search for SSBs associated with SIB1. At least CORESET#0, which is the CORESET for scheduling SIB1, may be configured via the MIB or dedicated RRC signaling.

[0083] The set of PDCCH candidates monitored by the UE is defined in terms of PDCCH search space sets. The search space set may be a common search space (CSS) set or a UE-specific search space (USS) set. Each CORESET configuration is associated with one or more search space sets, and each search space set is associated with one CORESET configuration. For each DL BWP configured for the UE within the serving cell, the UE may be provided with one or more search space sets via higher layer signaling (e.g., RRC signaling). For each of the above search space sets, the UE may be provided with information about the associated CORESET and parameters used to determine PDCCH monitoring occasions at which to perform PDCCH monitoring (e.g., parameters monitoringSlotPeriodicityAndOffset regarding PDCCH monitoring period and PDCCH monitoring offset, monitoringSymbolsWithinSlot regarding intra-slot PDCCH monitoring pattern indicating the first symbol(s) of the CORESET for PDCCH monitoring within each slot in which the UE monitors the PDCCH, and parameter duration indicating the number of slots in which the corresponding search space set exists).

[0084] The UE determines the PDCCH monitoring time on the active DL BWP from the PDCCH monitoring time, the PDCCH monitoring offset, and the PDCCH monitoring pattern within the slot. The symbol corresponding to the bit set to 1 in the RRC parameter monitoringSymbolsWithinSlot is the start symbol of the PDCCH monitoring time, and the PDCCH monitoring time includes a number of OFDM symbols corresponding to the duration of the CORESET associated with the search space in the time domain, and is defined by the PRBs constituting the CORESET in the frequency domain.

[0085] Figure 5 illustrates multi-beam operation in a 3GPP-based system.

[0086] 5G and subsequent 3GPP-based systems can utilize high ultra-high frequency bands, such as the millimeter wave frequency band (mmWave) above 6 GHz, to transmit data to multiple users while maintaining high data rates by utilizing a wide frequency band. However, the millimeter wave frequency band has frequency characteristics that show very rapid signal attenuation over distance due to the use of such a high frequency band. Therefore, when using a band of at least 6 GHz or higher, 3GPP-based systems use a narrow beam transmission technique to compensate for the rapid propagation attenuation characteristics by concentrating energy in a specific direction rather than omnidirectionally transmitting the signal, thereby solving the problem of reduced coverage due to rapid propagation attenuation. However, when providing service using only a single narrow beam, the service range of a single BS is limited, so the BS gathers multiple narrow beams to provide service as a wide beam.

[0087] Figure 6 illustrates an example of SS / PBCH blocks (SSBs) being transmitted on a cell.

[0088] In 3GPP-based systems, each synchronization signal (SS) / physical broadcast channel (PBCH) block (SS / PBCH block, i.e., SSB) is associated with a beam. For example, during a half-frame, different SSBs can be transmitted in different spatial directions (using different beams that span the cell's coverage area). The possible time positions of the SSBs within a half-frame are determined by the subcarrier spacing, and the periodicity of the half-frames in which the SSBs are transmitted is set by the network. Multiple SSBs can be transmitted within the carrier's frequency span. Different indices of the SSBs transmitted / detected on a cell can correspond to different BS (wide) Tx beams.

[0089] In 3GPP-based systems, multi-beam operation is based on beam switching / beam scanning, which transmits / receives signals while changing beam directions over time. For example, assuming that a BS supports up to N transmission beams, beam sweeping can be performed, which transmits a synchronous signal block (SSB) consisting of PSS, SSS, and PBCH in each of up to N beam directions (see SSB beam sweeping in Fig. 5).

[0090] Referring back to Figure 5, the UE can measure the power of SSB(s) received from BS transmission (Tx) beams using a wide reception (Rx) beam and select its preferred beam. For example, the UE can select one SSB from among the detected / received SSBs. 3GPP-based systems specify a specific mapping between SSBs and random access channel (RACH) occasions to allow the network to know which beam the UE has selected. A RACH occasion is a time and frequency resource available for transmission of a RACH preamble. The network can provide the UE with information about how many SSBs can be mapped to a single RACH occasion and how many preamble indices can be mapped to a single SSB. For example, if the network configures the number of SSBs per RACH epoch as 1 / N, then one SSB is associated with N RACH epochs (where N is a positive integer), and if the network configures the number of SSBs per RACH epoch as N, then N preamble indices are mapped to a single SSB. The UE selects an SSB from among the SSBs detected / received by the UE on the cell, and selects a RACH epoch based on the selected SSB to transmit. The BS can detect the RACH epoch including the PRACH from the UE through BS Rx beam sweeping, thereby knowing which SSB among the SSBs transmitted on the cell the UE has selected. The BS can determine a BS Tx beam for communication with the UE based on the SSB selected by the UE.

[0091] For finer beam tuning, CSI-RS may be transmitted. The BS may perform beam refinement using CSI-RS transmissions in narrower beams around the BS Tx beam determined based on the RACH timing at which the PRACH from the UE is detected (see CSI-RS beam sweeping in FIG. 5 ). The UE may measure the power of CSI-RSs received from these BS Tx narrow beams and report to the BS which of the BS Tx narrow beams it prefers. For example, the UE may measure CSI-RSs on CSI-RS resources to select at least one CSI-RS resource, and report to the BS a CSI-RS resource indicator (CRI) and a corresponding reference signal received power (RSRP) of the selected CSI-RS resource. The BS may determine a BS Tx narrow beam based on the CRI and / or corresponding RSRP reported by the UE, and repeatedly transmit CSI-RS through the BS Tx narrow beam (see P3 CSI-RS beam sweeping in FIG. 5) so that the UE performs Rx beam sweeping to find an appropriate UE Rx beam. The UE may measure the power of the CSI-RS received at each UE Rx beam to find an appropriate UE Rx beam.

[0092] A UE can detect a beam failure using CSI-RS / SSB. For example, if the L1-RSRP for a beam to be connected falls below a certain limit, the UE determines that the beam has failed and searches for other candidate beams with good quality. If a predetermined number of beam failures are detected, a beam failure recovery (BFR) procedure can be triggered using the candidate beam. The network can provide the UE with an identifier (ID) of an SSB transmitted by a cell, which is used to determine a candidate beam for BFR, and a preamble index used when performing BRF when selecting the candidate beam identified by the SSB. If the UE detects a predetermined number of beam failures, the network sends a BRF request to the network by transmitting a PRACH associated with the SSB ID, and the network provides a random access response (RAR) to the UE in response to the BRF request.

[0093] 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 extension, and spatial Rx parameters.

[0094] A beam for a target channel / signal can be indicated by a transmission configuration indicator (TCI) from a UE. A TCI state can be configured / indicated for a PDCCH / PDSCH. The TCI state can include information about a source reference signal and quasi-co-location (QCL) information. For example, an RRC configuration TCI-State can be provided by a BS to the UE, which associates one or more DL reference signals with a corresponding quasi-co-location (QCL) type. Each TCI state includes parameters that configure a QCL relationship between one or two downlink reference signals (DL RSs) and DM-RS ports of a PDSCH, DM-RS ports of a PDCCH, or CSI-RS port(s) of a CSI-RS resource. For example, each RRC configuration TCI-Sate may include a TCI-State ID and QCL-Info, and may include a CSI-RS resource ID or SSB index for a DL RS for which the QCL information is provided. The QCL relationship of the TCI-State is configured by the upper layer parameter qcl-type1 for the first DL RS and the upper layer parameter qcl-type2 for the second DL RS (if configured). The QCL types corresponding to each DL RS are given by the upper layer parameter qcl-type in the QCL-Info and may take one of the following values:

[0095] - 'typeA': {Doppler shift, Doppler spread, average delay, delay spread}

[0096] - 'typeB' : {Doppler shift, Doppler spread}

[0097] - 'typeC' : {Doppler shift, average delay}

[0098] - 'typeD' : {Spatial Rx parameter}.

[0099] Figures 7 and 8 are illustrated to explain the multi-beam operation of PDCCH.

[0100] A CORESET is associated with one or more search space (SS) sets. The UE attempts to detect PDCCH by monitoring PDCCH monitoring occasions of the SS sets.

[0101] In some implementations or scenarios, for multi-beam operation for PDCCH, up to a predefined number (e.g., 64) of TCI states per CORESET for PDCCH may be configured to the UE via RRC signaling. The BS may activate one (or two) of the TCI states for the CORESET via a MAC control element (CE). When a UE is configured with the RRC parameter sfnSchemePdcch set to 'sfnSchemeA' and a CORESET is activated with two TCI states, the UE may assume that the DM-RS port(s) of the PDCCH in the CORESET are pseudo-co-located with the DL-RSs of the two TCI states. When a UE is configured with an RRC parameter sfnSchemePdcch set to 'sfnSchemeB' and a CORESET is activated with two TCI-states, the UE may assume that the DM-RS port(s) of the PDCCH in the CORESET are pseudo-co-located with the DL-RSs of the two TCI-states except for the QCL parameters {Doppler shift, Doppler spread} of the second indicated TCI-state. Here, the RRC parameter sfnSchemePdcch is used to configure a super frame number (SFN) for the PDCCH, and either sfnSchemeA or sfnSchemeB can be configured by the RRC parameter sfnSchemePdcch.

[0102] In this specification, the MAC control element (CE) provided to the UE by the network or BS is provided to the UE via the PDSCH, and the DCI is provided to the UE via the PDCCH. The MAC CE provided to the UE by the BS is included in a MAC PDU corresponding to a transport block in the physical layer, and the transport block can be transmitted via the PDSCH.

[0103] If TCI states are not explicitly set for a CORESET, the UE assumes an SSB beam for the CORESET. Here, the assumed SSB beam may refer to the reception beam used by the UE when receiving the SSB determined during the initial access process. For example, before the TCI state is set for the CORESET, the UE may perform the initial access by determining one SSB (hereinafter referred to as SSB#k) among the multiple SSBs received during the initial access process. The CORESET may be received based on the reception beam information assumed when receiving SSB#k (which may correspond to QCL type D, for example).

[0104] In some implementations of this specification, the TCI states set for CORESET may be a subset of the TCI states set for PDSCH.

[0105] Figure 8 illustrates TCI-state(s) indicating MAC CEs for PDCCH that may be used in some implementations of the present specification. For a more detailed description of the TCI-state(s) indicating MAC CEs, refer to 3GPP TS 38.321.

[0106] A UE that has received a MAC CE activation command for one (or two) of the TCI-states set for CORESET sends the activation command in slot k+3N. subframe,u slot +2 u*Applies in the first slot after kmac, where slot k is the slot in which the UE will transmit a PUCCH with HARQ-ACK information for the PDSCH for which the activation command is provided, u is an SCS configuration for the PUCCH in the slot when the activation command is applied, kmac is an RRC parameter regarding scheduling offset provided by the network if downlink and uplink frame timings are not aligned at the BS, and if kmac is provided, kmac is the number of slots for SCS configuration u=0, otherwise kmac=0. When the UE receives a MAC CE activation command for one (or both) of the provided TCI-states for a CORESET, the UE may assume that the DM-RS antenna ports associated with the PDCCH receptions in the CORESET are pseudo-co-located with one or more DL RSs configured by the TCI-states. The UE may set its analog beamforming coefficients for PDCCH receptions within the CORESET (i.e., for PDCCH monitoring) based on the activated TCI-state(s).

[0107] Figures 9 to 11 are drawings to explain the multi-beam operation of PDSCH.

[0108] For PDSCH, beam indications are defined and used independently from those for PDCCH. In some implementations or scenarios, for example, referring to FIG. 9, for multi-beam operation for PDSCH, N TCI states (e.g., up to 64 TCI states) may be configured to the UE via RRC signaling for PDSCH (S901). A set of TCI states may be activated by a MAC CE for PDSCH receptions. For example, eight TCI states may be activated by a TCI states activation / deactivation MAC CE for PDSCH (S902).

[0109] Figure 10 illustrates TCI-state activation / deactivation MAC CEs for PDSCH that may be used in some implementations of the present specification. For a more detailed description of the TCI-state activation / deactivation MAC CEs, please refer to 3GPP TS 38.321.

[0110] When a UE receives a MAC CE activation command for TCI-states of a serving cell or a set of serving cells and the UE wants to transmit a PUCCH with HARQ-ACK information in slot n corresponding to the PDSCH carrying the activation command, the indicated mapping between the TCI-states and the code points of the DCI field 'Transmission Setup Indication' is slot n+3N. subframe,u slot +(2 u / 2 u_kmac )*kmax, where u is the SCS setting for the PUCCH and u_kmax is the SCS setting for kmax, which is 0 for frequency range 1, and kmax is provided by the RRC parameter kmac. If the RRC parameter kmac is not provided, kmax = 0.

[0111] The BS may signal a DCI for scheduling a PDSCH to the UE, and the DCI may indicate a TCI state to be used for reception of the PDSCH among the TCI states activated by the TCI states activation / deactivation MAC CE (S903). The 'Transmission Configuration Indicator' field in the DCI may be used to indicate one of the TCI states activated by the MAC CE. When the maximum number of TCI states that can be activated by the MAC CE is 8, the size of the 'Transmission Configuration Indicator' field may be 3 bits. When the RRC parameter tci-PresentInDCI, which indicates whether a TCI field is present in the DCI format, is not enabled, for example, when the RRC parameter does not exist, the size of the 'Transmission Configuration Indicator' field may be 0 bits. A UE that receives the DCI that can be activated by MAC CE can set its analog beamforming coefficients based on the indicated TCI-state to receive the PDSCH, for example.

[0112] In some implementations, the TCI state for the PDSCH may be assumed differently depending on the time offset between the PDCCH carrying the DCI and the corresponding PDSCH. Referring to FIG. 11, if the time offset between the PDCCH carrying the DCI scheduling the PDSCH and the PDSCH is greater than or equal to timeDurationForQCL, the UE may assume the TCI state indicated by the 'Transmission Configuration Indicator' field in the DCI for the PDSCH, and if the time offset is less than timeDurationForQCL, the UE may assume a default beam. The default beam may correspond to a reception beam corresponding to a TCI state set in the CORESET of the PDCCH on which the DCI scheduling the PDSCH is transmitted. timeDurationForQCL defines the minimum number of OFDM symbols required by the UE to perform PDCCH reception and apply the QCL information received in the DCI for PDSCH processing. The number of OFDM symbols is measured from the end of the last symbol of the PDCCH reception to the beginning of the first symbol of the PDSCH reception. The following table illustrates timeDurationForQCL according to SCS.

[0113]

[0114] The UE may indicate to the network one of the minimum numbers of OFDM symbols for each SCS of 60 kHz, 120 kHz, 480 kHz and 960 kHz.

[0115] Figure 12 illustrates a non-terrestrial network (NTN) structure.

[0116] Recently, discussions are underway to enable 3GPP-based systems to support non-terrestrial networks (NTNs). NTNs are any network that includes non-terrestrial flying objects. If wireless communication via NTNs is enabled in 3GPP-based systems, the continuity of wireless communication services can be guaranteed, the reliability of wireless communication services can be enhanced through connectivity between various access technologies, and network resilience and reliability against disasters can be improved. For convenience of explanation, the following terminology will be used below.

[0117] - NTN: A radio access network consisting of BSs that provides non-terrestrial radio access to UEs using NTN payloads and NTN gateways mounted on airborne or space-borne NTN vehicles.

[0118] - NTN Gateway: An earth station located on the surface of the Earth that provides connectivity to NTN payloads using feeder links. An NTN Gateway is a transport network layer (TNL) node.

[0119] - NTN Payload: A network node mounted on a satellite or high altitude platform station that provides connectivity between service links and feeder links.

[0120] - Service Link: Wireless link between NTN payload and UE.

[0121] - Feeder link: A wireless link between the NTN gateway and the NTN payload.

[0122] - Satellite: A space-borne vehicle orbiting the Earth carrying an NTN payload.

[0123] - NTN cell: A cell that provides a service link between the UE and the NTN payload.

[0124] Referring to Figure 12, an NTN gateway is connected to an NTN payload mounted on a satellite or a high altitude platform system (HAPS) via a feeder link. The NTN payload is connected to a UE via a service link. The NTN gateway can be connected to the core network of a 3GPP-based system.

[0125] The NTN payload transmits a wireless protocol received from a UE (via a service link) to an NTN gateway (via a feeder link), and transmits a wireless protocol received from the NTN gateway (via a feeder link) to the UE (via a feeder link). An NTN gateway can service multiple NTN payloads, and an NTN payload can be serviced by multiple NTN gateways. For NTN, a tracking area can correspond to a fixed geographical area, and each mapping can be configured in the radio access network.

[0126] The following three time service links are supported:

[0127] - Earth-fixed service link: A service link that is provisioned by beam(s) that continuously cover the same geographic areas (e.g., in the case of GSO satellites).

[0128] - Quasi-Earth-fixed service link: A service link supplied by beam(s) that cover one geographic area for a limited period and another geographic area for another period (e.g., in the case of NGSOs that produce steerable beams).

[0129] - Earth-moving service link: A service link whose coverage area is supplied by beam(s) that glide over the Earth's surface (e.g., for NGSO satellites that produce fixed or non-steerable beams).

[0130] NTN can include satellite communication networks, air-to-ground networks, and UAV networks. One of the key concepts in NTN is that NTN cells are provided by non-geostationary orbit (NGSO) satellites that periodically orbit the Earth. Each satellite has its own orbit, which is included in the satellite position estimate information. Based on the satellite position estimate information, the network can predict feeder link switchover and manage UE mobility and radio resource control. A BS providing NTN access can broadcast orbital trajectory information or ephemeris information regarding coordinates for the NTN payload. EphemerisInfo can provide satellite position estimates in the form of position and velocity state vectors or in the form of orbital parameters. The following tables illustrate the EphemerisInfo information elements broadcast by the BS and describe the fields of the EphemerisInfo IE.

[0131]

[0132]

[0133] Satellite communication networks may include low Earth orbit (LEO) satellites, medium Earth orbit (MEO) satellites, and geosynchronous Earth orbit (GEO) satellites.

[0134]

[0135] The following are examples of NTN deployment scenarios.

[0136]

[0137] Referring to NTN Deployment-D3 scenario and NTN Deployment-D4 scenario, S-band of 2 to 4 GHz and Ka-band of 26 to 40 GHz are considered as satellite frequency bands for LEO.

[0138] Figure 13 illustrates an NTN deployment scenario. In particular, Figure 13 illustrates a case where multi-beam operation is applied to the NTN deployment-D4 scenario among the NTN deployment scenarios illustrated in Table 7.

[0139] Since LEO satellites operating in the Ka-band suffer from severe path loss, multi-beam operation may be considered for LEO satellites in the Ka-band, as illustrated in Fig. 13.

[0140] In the NTN deployment-D4 scenario, the beam footprint formed on the ground by beams steered from the satellite toward the ground area is fixed on the Earth. However, from the perspective of a UE on the ground, the beam direction that the UE must view changes over time. Below, implementations of this specification for cases where multi-beam operation is applied in the NTN deployment-D4 scenario are described.

[0141] NTN architectures can broadly be categorized into i) transparent architectures, where satellites relay wireless communication signals between BSs and UEs, and ii) non-transparent architectures, where satellites contain all or part of a BS to generate wireless communication signals and require sufficient on-board processing capabilities to function as a BS.

[0142] In the case of NTN, a large delay occurs due to the long distance between the gateway-satellite-UE. The delay occurring in the service link is T d,1 The delay occurring in the feeder link is called T d,2 In the case of a transparent architecture that relays wireless communication signals between BS and UEs, T d = T d,1 + T d,2 In the case of opaque architectures that generate radio communication signals directly from satellites, there is a delay of T d = T d,1 Delay occurs. The following table shows the expected UE-to-satellite delay depending on the satellite platform.

[0143]

[0144] Figure 14 illustrates beam switching for a satellite with multi-beam operation.

[0145] In some implementations, even though the beam footprint or tracking area is fixed, the transmission (Tx) beam (i.e., DL Tx beam) of the NTN payload to the UE keeps changing, and the UE also needs to change its reception (Rx) beam (i.e., DL Rx beam) to match the constantly changing DL Tx beam according to the satellite's motion. Since the UE Rx beam is associated with the TCI state, a UE Rx beam change is associated with a TCI state change. However, unlike terrestrial networks, NTN has the characteristics of long propagation delay, wide beam coverage and large delay, satellite movement, high Doppler shift, etc. Considering the long delay due to these NTN characteristics, dynamic TCI state change based on MAC CE / DCI may not be appropriate.

[0146] Figure 15 illustrates a problem when applying a transmission configuration indicator (TCI)-state change based on a conventional medium access control (MAC) control element (CE) and / or downlink control information (DCI) to NTN. In Figure 15, T d,1 represents the propagation delay that occurs between the UE and the satellite, and T d,2 represents the propagation delay that occurs between the satellite and the BS. In this case, the propagation delay T between the UE and the BS offset Silver T offset = T d,1 + T d,2 can be expressed as

[0147] Referring to Fig. 15, when the BS indicates the TCI state corresponding to beam #1 at t=t1, the UE and the UE receive the indication at time t1 after T offsetIt may be received at a later time, for example, at time t = t2. During the long propagation delay of NTN, due to satellite motion, a different beam (e.g., beam #2) may be the optimal beam at time t = t2, rather than beam #1, which is the optimal beam expected by the BS. In this case, if the UE changes the UE Rx beam to beam #1 indicated by the BS at time t = t2, the DL channel / reception may not be performed properly. Therefore, in NTI, it may not be appropriate to change the beam through MAC CE / DCI-based dynamic TCI-state indication due to the long propagation delay and satellite motion.

[0148] However, in the existing 5G NR process, it is difficult to predict the BS Tx beam for the UE depending on the movement of the UE, whereas the satellite's orbit is fixed and the satellite's position / velocity can be provided to the UE through position estimation information, so the satellite's movement can be predicted at the BS and / or UE. Below, some implementations of this specification are described that can solve problems that may arise due to the large propagation delay of NTN, taking into account that the satellite's position / velocity is predictable. For some implementations of this specification, the following basic assumptions apply.

[0149] > Follows the existing 5G beam design.

[0150] > Multiple SSBs are transmitted on different beams.

[0151] > The UE recognizes beam information based on the received SSB / CSI-RS. The beam information may be, for example, a transmission configuration indicator (TCI), quasi-colocation (QCL), or spatial information.

[0152] > Tx beamforming depends on BS.

[0153] > Rx beamforming is up to the UE.

[0154] <PDCCH의 다중 빔 동작>

[0155] Some implementations of this specification may enable beam prediction and autonomous beam switching.

[0156] Figures 16 and 17 illustrate a flow of two-level multi-beam operation for PDCCH according to some implementations of the present specification. In particular, Figure 16 illustrates a flow of multiplexed beam operation at a UE according to some implementations of the present specification, and Figure 17 illustrates a flow of multiplexed beam operation at a BS according to some implementations of the present specification.

[0157] In some implementations of the present specification, a two-level multi-beam operation is performed for PDCCH. In the first level, beam group activation (which is less delay sensitive) is performed (e.g., MAC CE-based beam group activation, which is less delay sensitive than DCI-based activation), and in the second level, beam activation is performed within the activated beam groups. In some implementations, the beams within a group may be composed of beams with similar beamforming characteristics (e.g., spatial correlation characteristics), and beams within different groups may be composed of beams with different beamforming characteristics. In some implementations of the present specification, for the first level of the two-level multi-beam operation, multiple TCI groups, each containing multiple TCI states, may be configured to the UE for the PDCCH via RRC signaling (S1601, S1701). In some implementations of the present specification, the TCI states configured for CORESET may be a subset of the TCI states configured for PDSCH.

[0158] One of the TCI groups configured for a CORESET can be activated autonomously based on satellite information (e.g., EphemerisInfo) or by a MAC CE (S1603, S1703). In the second level of the two-level multi-beam operation, the BS can transmit a MAC CE activating one of the TCI states within the activated TCI group (S1705), and the UE can receive the MAC CE (S1605). The BS and the UE can activate a TCI state indicated by the MAC CE among the TCI states within the activated TCI group (S1607, S1707). In some implementations, a PDCCH scheduling a PDSCH carrying the MAC CE can be received based on a TCI state of a preset activated CORESET. For example, before the TCI state is set for CORESET, the UE may receive the PDCCH based on the reception beam information or TCI state (e.g., which may correspond to QCL type D) corresponding to the SSB used when performing the initial connection among the SSBs received during the initial connection process.

[0159] In some implementations of the present specification, BS activating a TCI state may mean that the satellite transmits a PDCCH to the UE using a DL transmit beam corresponding to the activated TCI state. For example, if one of the TCI states configured for a CORESET is activated by two-level multi-beam operation according to some implementations of the present specification, the BS may perform a PDCCH transmission on the SS set(s) of the CORESET using a DM-RS port QCLed with an SSB or CSI-RS resource corresponding to the activated TCI state. In some implementations of the present specification, UE activating a TCI state may mean that it assumes the activated TCI state for PDCCH reception (e.g., PDCCH monitoring), and the UE may set its analog beam coefficients for the UE Rx beam based on the activated TCI state. The UE may perform PDCCH monitoring or PDCCH decoding within the SS set(s) of the CORESET using the QCL information provided by the activated TCI state. For example, the UE may perform PDCCH monitoring or PDCCH decoding assuming that the DM-RS port of the PDCCH within the SS set(s) associated with the CORESET is in a QCL relationship with the DL RS for the activated TCI state.

[0160] Figure 18 illustrates TCI state changes according to two-level multi-beam operation for PDCCH according to some implementations of the present specification. In the example of Figure 18, it is assumed that at time t=t1, the UE is expected to be in TCI state #1 or TCI state #2, and at time t=t3, the UE is expected to be in TCI state #3 or TCI state #4, as illustrated in Figure 18(a).

[0161] Referring to FIG. 18(b), for example, the BS may configure the UE(s) with, for example, TCI-state #1 and TCI group #1 including TCI-state #1 and TCI group #2 including TCI-state #2 and TCI-state #3 for CORESET. In some implementations, the TCI group #1 among the TCI group #1 and the TCI group #2 may be automatically activated at time t=t1. Alternatively, in some implementations, the TCI group #1 among the TCI group #1 and the TCI group #2 may be activated by a MAC CE provided by the BS at time t=t1. Either the TCI-state #1 or the TCI-state #2 within the TCI group #1 may be activated by a MAC CE provided by the BS. At or before time t=t3, group switching between the TCI group #1 and the TCI group #2 to the TCI group #2 may be performed automatically or by MAC CE provided by the BS. If a first TCI-state among the TCI-state #3 and the TCI-state #4 among the activated TCI group #2 is indicated by the BS at time t=t3, the UE may use the TCI-state #3 for PDCCH reception / PDCCH monitoring, and if a second TCI-state among the TCI-state #3 and the TCI-state #4 among the activated TCI group #2 is indicated by the BS at time t=t3, the UE may use the TCI-state #4 for PDCCH reception / PDCCH monitoring.

[0162] According to some implementations of this specification, beam mismatch over time can be reduced by indicating one of the TCI states within a group. Since the UE has already performed a TCI group transition when a specific TCI state is indicated, TCI state transitions can be facilitated. Furthermore, since one of the TCI states within a group is indicated, the signaling overhead for TCI state changes can be reduced compared to existing methods.

[0163] In some implementations, for TCI group activation via MAC CE, the UE may assume a default beam group (i.e., a default TCI group) before receiving the TCI group activation MAC CE. In some implementations, the default beam group may be the beam group with the lowest index (i.e., the TCI group with the lowest index) or a (pre-)configured group. Alternatively, the default beam group may be a TCI group to which a TCI-state includes, as DL RS information, an SSB index for an SSB selected by the UE if the number of SSBs exceeding the specific threshold is greater than 1 among the SSB(s) detected on the cell. The BS may assume, as the default beam group, a TCI group to which a TCI-state includes, as DL RS information, an SSB index of an SSB for which a PRACH is detected among the SSBs transmitted on the cell. Alternatively, a TCI group including a TCI state that includes an SSB index selected during the initial connection process as DL RS information may be used as the default beam group. Alternatively, the default beam group may be a TCI group including a CSI-RS resource ID for a CSI-RS resource selected by the UE as DL RS information when the number of CSI-RS resources exceeding a specific threshold among the CSI-RS resource(s) set on the cell or the number of CSI-RS resources exceeding the specific threshold is greater than 1.

[0164] In some implementations, a TCI group can be automatically switched from the initially activated group. In some implementations, a TCI group pattern can be (pre-)defined or (pre-)configured for automatic TCI group switching. For example, according to a (pre-)defined TCI group pattern, if group #n is first activated at t=t0, group #(n+k1) can be activated at t=t1, and group #(n+k2) can be activated at t=t2. The group switching timing (e.g., t1, t2, …) can be determined based on a (pre-)configured period or timer. The changed group index (e.g., k1, k2, …) can be determined incrementally in the index (e.g., {+1, +2, +3, …}) or based on a (pre-)configured pattern. For example, the following methods can be considered for automatic TCI group switching:

[0165] > Alt 1. Timer-based

[0166] A UE can perform a TCI group switch based on a timer. For example, the UE can start a preset timer at a specific time point T0, and when the timer expires, the UE can switch TCI groups. The timer for TCI group switch can be determined based on one of the following: That is, the time value for which the timer runs can be determined based on one of the following:

[0167] >> Alt 1-1. The UE can set a timer for TCI group switching. For example, the NTN configuration may include a value for the timer for TCI group switching.

[0168] >> Alt 1-2. The UE can calculate a timer for TCI group switching based on satellite information (e.g., EphemerisInfo). The UE can report this timer to the BS.

[0169] The point in time T0 when the timer starts can be determined by one or a combination of one or more of the following:

[0170] >> Alt 1-3. T0 may correspond to the time at which the initial access procedure is completed. For example, this may correspond to the time at which the UE receives a response to Message 3 (Msg3), an uplink transmission scheduled by a random access response to the transmission of the random access preamble during the initial access procedure (e.g., the time at which Message 4 (Msg4), used for contention resolution, is received).

[0171] >> Alt 1-4. T0 may correspond to the most recent point in time when a TCI group was initialized or a TCI group transition occurred.

[0172] >> Alt 1-5. A timer-triggering indicator can be transmitted from the BS to the UE, with T0 representing the time at which the indicator is received. The timer-triggering indicator can be transmitted from the BS to the UE via DCI or a MAC control element (CE).

[0173] > Alt 2. Periodicity-based

[0174] For each cycle and timing (i.e., time instance), the UE changes TCI groups. The cycle and time instance for TCI group switching can be determined based on one of the following:

[0175] >> Alt 2-1. The start time and period can be set to the UE by the network. For example, if the start time = 1 and the period = 5 are set to the UE for TCI group switching, the UE can perform TCI group switching at time units (e.g., slots, subframes, or frames) 1, 6, 11, and 16, respectively. In some implementations, a parameter periodicityAndOffset is defined that represents the start time and period for TCI group switching, and periodicityAndOffset can be provided to the UE by the network. In the NTN Deployment-D4 scenario, since UEs within the beam footprint covered by the satellite are provided with service links through the same or similar BS Tx beams over time, in some implementations of the present specification, the network can broadcast periodicityAndOffset through the PBCH or system information of the NTN cell.

[0176] >> Alt 2-2. The time pattern and period can be configured by the network to the UE. For example, if a time pattern is configured to the UE, where the period corresponds to 10 time units (e.g., 10 slots, 10 subframes, or 10 frames) and time units 0, 3, and 5 within the period are defined as instances for TCI group switching, then TCI group switching can be performed at time units 0, 3, and 5, respectively. In the NTN Deployment-D4 scenario, since UEs within the beam footprint covered by the satellite are provided with service links through the same or similar BS Tx beams over time, in some implementations of this specification, the network may broadcast the periodicityAndOffset via the PBCH or system information of the NTN cell.

[0177] In some implementations of this specification, the following methods may be considered for automatic TCI group switching:

[0178] > Alt 1. TCI group index increment

[0179] For example, TCI group index k for triggering instance n for beam switching. n = k0+ mod (n, N group ) can be determined. Here, k0 can correspond to the first activated TCI group and N group may correspond to the total number of different TCI groups. For example, N group may be the total number of TCI groups set.

[0180] As another example, if the current TCI group index is k, then the TCI group index k for the nth triggering instance n for TCI group switching n = (k + △k*n), where △k is the TCI group index offset between triggering instances. △k can be set to the UE by the BS or determined by the UE based on satellite information (e.g., EphemerisInfo).

[0181] > Alt 2. Predefined TCI group index patterns (semi-static)

[0182] A set of TCI group indices (e.g., a set of TCI group indices) is predefined, and the TCI group indices can be changed in a predefined order in a triggering instance for a TCI group transition. For example, if a set of TCI group indices {1, 3, 4, 7} is predefined, and the triggering instances for a TCI group transition are t = t1, t = t2, t = t3, and t = t4, a TCI group transition to a TCI group that is TCI group #1 can be performed in the triggering instance t = t1, a TCI group transition to a TCI group that is TCI group #3 can be performed in the triggering instance t = t2, a TCI group transition to a TCI group that is TCI group #4 can be performed in the triggering instance t = t3, and a TCI group transition to a TCI group that is TCI group #7 can be performed in the triggering instance t = t4. In some implementations of this specification, TCI group indices within a set of TCI group indices may be applied cyclically for triggering instances. For example, a TCI group index set consisting of N TCI group indices is predefined, and the i-th TCI group index among the N TCI group indices is k' i (where i=0,...,N-1), then the beam index k for the n-th triggering instance n n= {k0+ mod (n, N)}, where k0 may be a TCI group index initially determined by the UE by applying the set of TCI group indices. For example, during a cell search process, a random access process is performed to select one of the SSBs received on a cell and transmit a PRACH associated with the selected SSB to the network, and k0 may be a TCI group index determined for CORESET #0 set by the PBCH in the SSB. In some implementations, k0 may be indicated to the UE(s) by the network as a TCI group index for a certain triggering instance (e.g., an initial triggering instance). The UE may determine the TCI group index k for the n-th triggering instance n after a predefined or preset initial triggering instance. n = {k0+ mod (n, N)} can be determined as the TCI group to be used for downlink communication.

[0183] In some implementations of the present specification, a UE may receive an NTN configuration including parameters (e.g., location estimation data, etc.) for the UE to access a wireless communication service (e.g., 5G, 6G, etc.) via an NTN connection. The NTN configuration may include parameter(s) for triggering a beam switch according to some implementations of the present specification (e.g., a timer for TCI group switching, information related to a start time and period for TCI group switching, or information related to a time pattern and period for TCI group switching) and / or parameter(s) for a TCI group switching method (e.g., a TCI group index offset, a TCI group pattern, etc.).

[0184] With respect to the second level of the two-level multi-beam operation of this specification, the following beam activations (i.e., TCI-state activations) may be considered.

[0185] > Alt 1. Activate TCI-state based on both group index (i.e. group identifier (ID)) and TCI-state index (i.e. TCI-state ID)

[0186] >> Both group ID and TCI-state ID can be indicated by MAC CE. For example, if group ID = X and TCI-state ID = Y are indicated, the UE can activate TCI-state Y within group X for PDCCH monitoring. Here, TCI-state ID = Y may not be a value identifying one of the entire TCI-states configured for CORESET, but may be a value identifying one of the TCI-states within the TCI group. For example, assuming that the TCI group contains M TCI-states, a UE that receives TCI-state ID = Y can activate the TCI-state with TCI-state ID = Y, assuming that the M TCI-states within the TCI group are assigned TCI-state IDs #0 to TCI-state #(M-1). In some implementations of this specification, a MAC CE indicating a TCI-state ID may indicate one of TCI-state #0 to TCI-state #(L-1) based on the maximum number L of TCI-states that can be included in the group. In other words, in TCI-state ID = Y, Y may be one of 0 to (L-1).

[0187] >> In some implementations, taking into account that the UE and satellite move over time, the indicated group ID (= X) may be replaced with the currently active group ID (= X act ) can be additionally judged whether the above-indicated group ID (= X) is the same as the currently activated group ID (= X act ) is not the same, the following actions may be considered:

[0188] >>> The UE may activate group X according to the MAC CE command. The UE may activate a TCI state corresponding to TCI state ID = Y among the TCI states within the group X for PDCCH monitoring. In some implementations, the UE may report group mismatch to the BS so that the BS can utilize it in future beam update.

[0189] >>> The above UE ignores the above group X activation command and the currently activated group X act can maintain. In some implementations, the UE may maintain group X based on the MAC CE. act Among my TCI states, the TCI state corresponding to TCI state ID = Y can be activated for PDCCH monitoring. In some implementations, the UE can report group mismatch to the BS so that the BS can utilize it for beam update later.

[0190] > Alt 2. Activate TCI state based on TCI state ID

[0191] >> UE selects the group to which the TCI-state change will be applied to be the currently active group X act It can be assumed that.

[0192] >> If TCI-State ID = Y is indicated, the UE is currently in active group X act Among my TCI states, the TCI state corresponding to TCI state ID = Y can be activated for PDCCH monitoring.

[0193] According to some implementations of this specification, the UE can well determine the TCI state for the DL channel / signal even in environments with large propagation delay.

[0194] <PDCCH Monitoring Adaptation with Beam Switching>

[0195] Among the implementations of the present specification described above, implementations related to automatic UE Rx beam switching for the same CORESET (i.e., changing TCI-state for the same CORESET) may not be applicable if a satellite's Tx beam is associated with a particular OFDM symbol(s) for PDCCH transmission. For example, if a UE applies TCI-state #1 corresponding to a satellite's Tx beam #1 for a CORESET to OFDM symbols #1 to #4 by automatic UE Rx beam switching, and in OFDM symbols #1 and #2, Tx beam #1 of the satellite is used for the UE or a beam footprint to which the UE belongs, and in OFDM symbols #3 and #4, Tx beam #2 of the satellite is used for the UE or a beam footprint to which the UE belongs, the TCI-state that the UE applies for the CORESET in OFDM symbols #3 and #4 may not correspond to the satellite's Tx beam used for the UE in OFDM symbols #3 and #4. In this case, it is preferable for the UE to change the PDCCH monitoring occasions according to the satellite's Tx beam rather than changing the UE Rx beam (i.e., TCI-state).

[0196] Figure 19 illustrates the concept of PDCCH monitoring adaptation according to some implementations of the present specification. In the example of Figure 19, it is assumed that the UE applies TCI-state #1 at time t=t1 and TCI-state #2 at time t=t2, as illustrated in Figure 19(a).

[0197] Below, implementations of this specification regarding PDCCH monitoring timing adaptation that depend on beam switching are described in more detail. The following basic assumptions apply to the implementations of this specification regarding PDCCH monitoring timing adaptation described below.

[0198] > The UE operates with automatic beam switching. For example, the UE operates with automatic beam switching such that TCI#n is assumed at time t=t0, TCI#(n+k1) is assumed at time t=t1, and TCI#(n+k2) is assumed at time t=t2.

[0199] > The above beam switching pattern is (pre-)defined. For example, TCI switching timings (e.g., t1, t2, ...) can be determined based on a (pre-)configured cycle or timer. TCI index, TCI-state indices (e.g., k1, k2, ...) can be determined incrementally in the index (e.g., {+1, +2, +3, ...}) or based on a (pre-)configured pattern.

[0200] I<PDCCH의 다중 빔 동작> In some implementations of this specification described in , implementations related to automatic beam switching change the UE Rx beam (e.g., TCI-state) depending on the PDCCH monitoring time. For example, UE Rx automatic beam switching (or automatic TCI-state switching) causes the UE to change the Rx beam (or TCI-state) over time for the same CORESET. In contrast, in some implementations of this specification described below, the CORESET or search space (also called search space set) to be monitored by the UE is changed or selected depending on the changing UE Rx beam (or TCI-state). For example, referring to FIG. 19, when a UE moves from an area supported by Tx beam #1 of a BS / satellite to an area supported by Tx #2 of the BS / satellite, the UE may perform PDCCH monitoring according to the SS set(s) of CORESET#1 by applying TCI-state #1 in the area supported by Tx beam #1, and may perform PDCCH monitoring according to the SS set(s) of CORESET#2 by applying TCI-state #2 in the area supported by Tx beam #2.

[0201] > Alt 1. Autonomous CORESET switching

[0202] Figure 20 illustrates autonomous CORESET switching according to some implementations of this specification.

[0203] For each DL BWP configured for a UE in a serving cell, one or more CORESETs may be configured. TCI states may be configured for the UE per CORESET. In some implementations of the present specification, for a time duration when TCI#m applies, the UE selects CORESET(s) configured with TCI#m, wherein TCI#m is activated (by automatic beam switching) for the CORESET(s) (automatic TCI state activation). For the time duration when TCI#m applies, the UE performs PDCCH monitoring with the CORESET(s) activated by TCI#m. That is, for the time duration when TCI#m applies, it is assumed that the CORESET(s) for which TCI#m is configured as a TCI state are activated, and the UE may perform PDCCH monitoring according to the SS sets of the CORESET(s).

[0204] Referring to FIG. 20, for example, if TCI#1 is assumed for a UE during slots 0 to 5 and TCI#2 is assumed for the UE during slots 6 to 9, and CORESET#1 is set to TCI#1 and CORESET#2 is set to TCI#2, the UE may perform PDCCH monitoring for CORESET#1 with TCI#1 set during slots 0 to 5 (i.e., PDCCH monitoring according to SS set(s) of CORESET#1), and PDCCH monitoring for CORESET#2 with TCI#2 set during slots 6 to 9 (i.e., PDCCH monitoring according to SS set(s) of CORESET#2).

[0205] In some implementations, for a time period during which TCI#m applies, if there is no CORESET with TCI#m set, the UE may act as follows:

[0206] >> Alt 1-1. If there is no CORESET for which TCI#m is set as TCI-state during the time period to which TCI#m applies (or if the PDCCH monitoring timing of all SS set(s) associated with a CORESET for which TCI#1 is set as TCI-state is not within the time period), the UE may perform PDCCH monitoring by assuming TCI#m for all CORESETs (set for the corresponding cell or active DL BWP). Since the UE monitors all CORESETs (set for the corresponding cell or active DL BWP) with TCI#m, the BS / satellite may transmit PDCCH transmission(s) to the UE through any CORESET (set for the corresponding cell or active DL BWP) based on TCI#m. This allows PDCCH transmission / reception to continue smoothly even when a mismatch occurs in beam information for the CORESET between the UE and the satellite / BS.

[0207] >> Alt 1-2. If there is no CORESET for which TCI#m is set as TCI-state during the time period to which TCI#m applies (or if the PDCCH monitoring occasions of all SS set(s) associated with a CORESET for which TCI#1 is set as TCI-state are not within the time period), the UE may randomly select a CORESET among the CORESETs (set for the cell or active DL BWP) whose PDCCH monitoring occasion(s) of the associated SS set are within the time period and monitor the selected CORESET with TCI#m. Alt 1-2 may be useful in situations where the PDCCH monitoring capability of the UE is limited due to small buffer size or power of the UE. However, in this case, the BS / satellite may have to perform PDCCH transmissions on all CORESETs.

[0208] > Alt 2. Autonomous search space switching

[0209] Figure 21 illustrates autonomous search space switching according to some implementations of this specification.

[0210] Scenarios can be considered where TCI states are set / activated per search space (i.e., per search space set) rather than per CORESET. In these scenarios, TCI states are associated with the search space rather than the CORESET, and the operations described in Alt 1 can be performed based on the search space (set) rather than the CORESET. For example, the following can be applied to scenarios where TCI states are set per search space (set).

[0211] For each DL BWP configured for a UE in a serving cell, one or more CORESETs may be configured. Each CORESET configuration is associated with one or more SS sets, and each SS set is associated with one CORESET configuration. TCI states may be configured for the UE per SS set. In some implementations of the present specification, for a time duration during which TCI#m applies, the UE selects the SS set(s) configured with TCI#m. For the time duration during which TCI#m applies, the UE may perform PDCCH monitoring at PDCCH monitoring occasions determined by the SS set(s) activated by TCI#m. That is, for the time duration during which TCI#m applies, it is assumed that the SS set(s) for which TCI#m is configured as a TCI state are activated, and the UE may perform PDCCH monitoring according to the SS set(s).

[0212] Referring to FIG. 21, for example, if TCI#1 is assumed for a UE from time t=t1 to before time t=t2, and TCI#2 is assumed from time t=t2, and TCI#1 is set for SS set #1 and SS set #3, and TCI#2 is set for SS set #2, the UE can monitor SS set #1 and SS set #3 for which TCI#1 is set from time t=t1 to before time t=t2 (i.e., perform PDCCH monitoring according to SS set #1 and SS set #3), and can monitor SS set #2 for which TCI#2 is set from time t=t2 (i.e., perform PDCCH monitoring according to SS set #2).

[0213] In some implementations, for a time period during which TCI#m applies, if there is no SS set with TCI#m set, the UE may act as follows:

[0214] >> Alt 2-1. If there is no SS set for which TCI#m is set as a TCI-state during the time period to which TCI#m applies (or if the PDCCH monitoring time of all SS sets(s) for which TCI#1 is set as a TCI-state is not within the time period), the UE may perform PDCCH monitoring by assuming TCI#m for all SS sets (set for the corresponding cell or active DL BWP). Since the UE performs PDCCH monitoring by assuming TCI#m for all SS sets (set for the corresponding cell or active DL BWP), the BS / satellite may perform PDCCH transmission(s) to the UE through any SS set among the SS sets (set for the corresponding cell or active DL BWP) for which there is a PDCCH monitoring time within the time period.

[0215] >> Alt 2-2. If there is no SS set for which TCI#m is set as a TCI-state during the time period to which TCI#m applies (or if the PDCCH monitoring occasions of all SS set(s) for which TCI#1 is set as a TCI-state are not within the time period), the UE may randomly select N SS sets for which PDCCH monitoring occasions are within the time period and monitor the selected SS set(s) with TCI#m. N may be configured to the UE by the network / BS via higher layer signaling (e.g., RRC signaling).

[0216] According to some implementations of this specification, the UE can appropriately determine the TCI-state for the DL channel / signal even in environments with large propagation delay.

[0217] According to some implementations of this specification, even if the Tx beam (e.g., SSB index or CSI-RS resource ID) of the satellite / BS is associated with specific OFDM symbols for PDCCH transmission, the UE can automatically select an appropriate UE Rx beam (e.g., TCI-state) and perform PDCCH monitoring / reception appropriate to the TCI-state associated with a specific time period.

[0218] Implementations of this specification are described assuming NTN for ease of understanding; however, implementations of this specification are not limited to NTN and can also be applied to TN.

[0219] In the description of the implementations of the above-described specification, the Tx beam of the satellite / BS may be replaced with the beam of SSB or CSI-RS transmitted by the satellite / BS, and the Tx beam index of the satellite / BS may be replaced with the SSB index or CSI-RS resource ID.

[0220] Figure 22 illustrates the flow of downlink signal reception at a UE according to some implementations of the present specification.

[0221] A UE may perform operations according to some implementations of the present disclosure in connection with receiving a PDCCH. The UE may include at least one transceiver; at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations according to some implementations of the present disclosure. A processing device for the UE may include at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations according to some implementations of the present disclosure. A computer-readable (non-transitory) storage medium may store at least one computer program comprising instructions that, when executed by at least one processor, cause the at least one processor to perform operations according to some implementations of the present disclosure. A computer program or computer program product may be recorded on at least one computer-readable (non-transitory) storage medium and may contain instructions that, when executed, cause (at least one processor) to perform operations according to some implementations of the present specification.In the UE, the processing device, the computer-readable (non-transitory) storage medium, and / or the computer program product, the operations may include: receiving a TCI configuration for each of one or more CORESETs (S2201), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and QCL information; determining a first TCI state for a first time period (S2203); determining a first CORESET for which the first TCI state is set (S2205); and performing PDCCH monitoring based on the first TCI state for the first CORESET within the first time period (S2207).

[0222] In some implementations, the first TCI-state for the first time period may be determined based on a predetermined TCI transition pattern.

[0223] In some implementations, the operations may further include: receiving a setting regarding the predetermined TCI transition pattern.

[0224] In some implementations, the operations may include: performing PDCCH monitoring based on the first TCI-state for all CORESETs configured for the cell or active BWP, based on no CORESET having the first TCI-state set within the first time period, of the associated search space set for PDCCH monitoring.

[0225] In some implementations, performing PDCCH monitoring for the CORESET based on the first TCI-state may include: performing PDCCH monitoring for a search space set associated with the CORESET using a QCL relationship between a downlink reference signal for the first TCI-state and a demodulation reference signal of the PDCCH.

[0226] Figure 23 illustrates the flow of downlink signal transmission in a BS according to some implementations of the present specification.

[0227] A BS may perform operations according to some implementations of the present disclosure in connection with transmitting a PDCCH. The BS may include at least one transceiver; at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations according to some implementations of the present disclosure. A processing device for the BS may include at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations according to some implementations of the present disclosure. A computer-readable (non-transitory) storage medium may store at least one computer program comprising instructions that, when executed by at least one processor, cause the at least one processor to perform operations according to some implementations of the present disclosure. A computer program or computer program product may be recorded on at least one computer-readable (non-transitory) storage medium and may contain instructions that, when executed, cause (at least one processor) to perform operations according to some implementations of the present specification.In the BS, the processing device, the computer-readable (non-transitory) storage medium, and / or the computer program product, the operations may include: transmitting a TCI configuration for each of one or more CORESETs (S2301), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and QCL information; determining a first TCI state for a first time period (S2303); determining a first CORESET for which the first TCI state is set (S2305); and performing a PDCCH transmission based on the first TCI state for the first CORESET within the first time period (S2307).

[0228] In some implementations, the first TCI-state for the first time period may be determined based on a predetermined TCI transition pattern.

[0229] In some implementations, the operations may further include: transmitting a setting regarding the predetermined TCI transition pattern.

[0230] In some implementations, the actions may include: performing the PDCCH transmission based on the first TCI-state through one of the CORESETs set for the cell or active BWP, based on the absence of a CORESET for which the first TCI-state is set within the first time period of the PDCCH monitoring time of the associated search space set.

[0231] In some implementations, performing the PDCCH transmission for the CORESET based on the first TCI-state may include: performing the PDCCH transmission according to a search space set associated with the CORESET using a QCL relationship between a downlink reference signal for the first TCI-state and a demodulation reference signal of the PDCCH.

[0232] As described above, the examples disclosed herein are provided to enable those skilled in the art to implement and practice the present disclosure. While the examples have been described above with reference to the examples of the present disclosure, those skilled in the art will appreciate that various modifications and variations may be made to the examples of the present disclosure. Accordingly, the present disclosure is not intended to be limited to the examples described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0233] Implementations of this specification can be used in wireless communication systems, BSs, UEs, and other equipment.

Claims

1. When a user device receives a downlink signal in a wireless communication system supporting a non-terrestrial network (NTN), Receive a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; Determine the first TCI-state for the first time period; Determining the first CORESET in which the first TCI-state is set; and Comprising performing physical downlink control channel (PDCCH) monitoring based on the first TCI-state for the first CORESET within the first time period. Method for receiving downlink signals.

2. In paragraph 1, The first TCI state for the first time period is determined based on a predetermined TCI transition pattern. Method for receiving downlink signals.

3. In paragraph 2, Further comprising receiving a setting regarding the above-determined TCI transition pattern, Method for receiving downlink signals.

4. In paragraph 1, A method comprising: performing PDCCH monitoring based on the first TCI-state for all CORESETs set for the cell, based on the absence of a CORESET for which the first TCI-state is set within the first time period, in which the PDCCH monitoring time of the associated search space set is Method for receiving downlink signals.

5. In paragraph 1, Performing PDCCH monitoring for the CORESET based on the above first TCI-state: Comprising performing PDCCH monitoring for a search space set associated with the CORESET using a QCL relationship between a downlink reference signal for the first TCI-state and a demodulation reference signal of the PDCCH. Method for receiving downlink signals.

6. When a user device receives a downlink signal in a wireless communication system supporting a non-terrestrial network (NTN), At least one transceiver; at least one processor; and At least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations, said operations comprising: Receive a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; Determine the first TCI-state for the first time period; Determining the first CORESET in which the first TCI-state is set; and Comprising performing physical downlink control channel (PDCCH) monitoring based on the first TCI-state for the first CORESET within the first time period. User device.

7. In a processing device in a wireless communication system, at least one processor; and At least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations, said operations comprising: Receive a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; Determine the first TCI-state for the first time period; Determining the first CORESET in which the first TCI-state is set; and Comprising performing physical downlink control channel (PDCCH) monitoring based on the first TCI-state for the first CORESET within the first time period. Processing device.

8. In a computer-readable storage medium, The storage medium stores at least one program code including instructions that, when executed, cause at least one processor to perform operations, the operations comprising: Receive a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; Determine the first TCI-state for the first time period; Determining the first CORESET in which the first TCI-state is set; and Comprising performing physical downlink control channel (PDCCH) monitoring based on the first TCI-state for the first CORESET within the first time period. Storage medium.

9. In a wireless communication system supporting a non-terrestrial network (NTN), when a base station transmits a downlink signal, Transmitting a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; Determine the first TCI-state for the first time period; Determining the first CORESET in which the first TCI-state is set; and Including performing a physical downlink control channel (PDCCH) transmission based on the first TCI-state for the first CORESET within the first time period. A method for transmitting downlink signals.

10. In paragraph 9, The first TCI state for the first time period is determined based on a predetermined TCI transition pattern. A method for transmitting downlink signals.

11. In paragraph 10, Further comprising transmitting settings regarding the above-determined TCI transition pattern, A method for transmitting downlink signals.

12. In paragraph 9, A method comprising: performing the PDCCH transmission based on the first TCI-state through one of the CORESETs set for the cell, based on the absence of a CORESET for which the first TCI-state is set within the first time period, during which the PDCCH monitoring time of the associated search space set is A method for transmitting downlink signals.

13. In paragraph 9, Performing the PDCCH transmission for the CORESET based on the first TCI state: Including performing the PDCCH transmission according to the search space set associated with the CORESET by using the QCL relationship between the downlink reference signal for the first TCI-state and the demodulation reference signal of the PDCCH. A method for transmitting downlink signals.

14. In a wireless communication system supporting a non-terrestrial network (NTN), when a base station transmits a downlink signal, At least one transceiver; at least one processor; and At least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations, said operations comprising: Transmitting a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; Determine the first TCI-state for the first time period; Determining the first CORESET in which the first TCI-state is set; and Including performing a physical downlink control channel (PDCCH) transmission based on the first TCI-state for the first CORESET within the first time period. Base station.

15. In a processing device in a wireless communication system, at least one processor; and At least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations, said operations comprising: Transmitting a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; Determine the first TCI-state for the first time period; Determining the first CORESET in which the first TCI-state is set; and Including performing a physical downlink control channel (PDCCH) transmission based on the first TCI-state for the first CORESET within the first time period. Processing device.

16. In a computer-readable storage medium, The storage medium stores at least one program code including instructions that, when executed, cause at least one processor to perform operations, the operations comprising: Transmitting a transmission configuration indicator (TCI) configuration for each of one or more control resource sets (CORESETs), the TCI configuration including TCI states, each TCI state including information about a downlink reference signal and quasi co-locate (QCL) information; Determine the first TCI-state for the first time period; Determining the first CORESET in which the first TCI-state is set; and Including performing a physical downlink control channel (PDCCH) transmission based on the first TCI-state for the first CORESET within the first time period. Storage medium.

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