Methods for communicating using non-terrestrial network and apparatuses thereof

Abstract

The present disclosure relates to a technology for a terminal and a base station to perform communication using a non-terrestrial network. In one aspect, the present embodiments provide a method and apparatus for a terminal to perform communication using a non-terrestrial network (NTN), comprising the steps of: receiving configuration information from a base station for controlling cell measurement or cell measurement reporting in the non-terrestrial network; determining whether to perform cell measurement or cell measurement reporting using the configuration information; and controlling the cell measurement or cell measurement reporting operation according to the determination result.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a technology in which a terminal and a base station perform communication using a non-terrestrial network. BACKGROUND ART

[0002] The amount of data transmitted and received using wireless communication technology has been rapidly increasing along with the increased popularization of smartphones and other devices and the diverse utilization of wireless communication devices. In addition, as the importance of low latency has been emphasized, development of next-generation wireless communication technology (New Radio Access Technology, New RAT) succeeding LTE technology is in progress.

[0003] In addition, the number of terminals performing communication using wireless communication technology has been rapidly increasing, and demand for communication in various environments and locations is increasing. Under such circumstances, there has been a need to provide wider coverage and provide communication services even in environments where wire-connected base stations cannot be constructed.

[0004] To this end, research is being conducted on non-terrestrial networks that are wirelessly connected to a core network in the air rather than through base stations constructed on the ground. A Non-Terrestrial Network refers to a network or a network segment that uses airborne vehicles such as HAPS (High Altitude Platform) or spaceborne vehicles such as satellites for transmission.

[0005] In addition, in next-generation wireless communication technology, beam-related technologies are applied to provide more efficient communication services to terminals. However, in the case of non-terrestrial networks, the distance between a terminal and a base station (a network node such as a satellite) is very long, and when a plurality of beam-related technologies are applied, unnecessary increase in delay time during cell measurement and cell measurement reporting can be expected. Therefore, definition of a separate protocol related to cell measurement in non-terrestrial networks is required. Problem to be Solved

[0006] The embodiments may provide a method and apparatus for a terminal and a network node to communicate using a non-terrestrial network. means of solving the problem

[0007] In one aspect, the present embodiments provide a method for a terminal to perform communication using a non-terrestrial network (NTN), comprising the steps of receiving configuration information from a base station for controlling cell measurement or cell measurement reporting in the non-terrestrial network, determining whether to perform cell measurement or cell measurement reporting using the configuration information, and controlling the cell measurement or cell measurement reporting operation according to the determination result.

[0008] In another aspect, the present embodiments provide a method for a base station to perform communication using a non-terrestrial network (NTN), comprising the steps of: transmitting configuration information to a terminal to control cell measurement or cell measurement reporting in the non-terrestrial network; and receiving a cell measurement report based on the result of determining whether the terminal performs cell measurement or cell measurement reporting using the configuration information.

[0009] In another aspect, the present embodiments provide a terminal device comprising a receiving unit that receives configuration information from a base station for controlling cell measurement or cell measurement reporting in a non-terrestrial network, and a control unit that determines whether to perform cell measurement or cell measurement reporting using the configuration information and controls the cell measurement or cell measurement reporting operation according to the determination result, wherein the terminal performs communication using a non-terrestrial network (NTN).

[0010] In another aspect, the present embodiments provide a base station device comprising a transmitter that transmits configuration information to a terminal for controlling cell measurement or cell measurement reporting in a non-terrestrial network, and a receiver that receives a cell measurement report based on the result of the terminal determining whether to perform cell measurement or cell measurement reporting using the configuration information, in a method for a base station to perform communication using a non-terrestrial network (NTN). Effects of the invention

[0011] According to the embodiments, a method and apparatus for efficiently performing communication between a terminal and a base station using a non-terrestrial network can be provided. Brief explanation of the drawing

[0012] FIG. 1 is a diagram briefly illustrating the structure of an NR wireless communication system to which the present embodiment can be applied. FIG. 2 is a drawing illustrating the frame structure in an NR system to which the present embodiment can be applied. FIG. 3 is a diagram illustrating a resource grid supported by wireless access technology to which the present embodiment can be applied. FIG. 4 is a diagram illustrating the bandwidth part supported by the wireless access technology to which the present embodiment can be applied. FIG. 5 is a diagram illustrating an exemplary synchronization signal block in a wireless access technology to which the present embodiment can be applied. FIG. 6 is a diagram illustrating a random access procedure in a wireless access technology to which the present embodiment can be applied. Figure 7 is a diagram for explaining CORESET. Figure 8 is a diagram showing an example of different subcarrier spacings aligned at the symbol level. FIG. 9 is a diagram illustrating a cell measurement model in NR to which the present embodiment can be applied. FIG. 10 is a diagram illustrating an exemplary NTN scenario to which the present embodiment can be applied. FIG. 11 is a diagram illustrating the types of NTN platforms to which the present embodiment can be applied. FIG. 12 is a diagram illustrating an exemplary configuration of an NTN satellite beam to which the present embodiment can be applied. FIG. 13 is a diagram illustrating terminal operation according to one embodiment. FIG. 14 is a diagram illustrating the operation of a base station according to one embodiment. FIG. 15 is a diagram illustrating satellite orbit information in an exemplary manner according to one embodiment. FIG. 16 is a diagram illustrating parameter values ​​of satellite orbit information according to one embodiment. FIG. 17 is a diagram illustrating the beam failure detection duration according to the beam change in accordance with the present embodiment. FIG. 18 is a drawing for explaining a terminal configuration according to one embodiment. FIG. 19 is a drawing for explaining the configuration of a base station according to one embodiment. Specific details for implementing the invention

[0013] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the exemplary drawings. In assigning reference numerals to the components of each drawing, the same components may have the same reference numeral as much as possible, even if they are shown in different drawings. Furthermore, in describing the embodiments, if it is determined that a detailed description of related known components or functions may obscure the essence of the technical concept, such detailed description may be omitted. Where terms such as "comprising," "having," or "consisting of" are used in this specification, other parts may be added unless "only" is used. Where a component is expressed in the singular, it may include a plural unless otherwise specified.

[0014] Additionally, terms such as first, second, A, B, (a), (b), etc., may be used to describe the components of the present disclosure. These terms are used merely to distinguish the components from other components, and the nature, order, sequence, or number of the components are not limited by such terms.

[0015] In describing the positional relationship of components, where it is stated that two or more components are "connected," "combined," or "joined," it should be understood that while the two or more components may be directly "connected," "combined," or "joined," they may also be "connected," "combined," or "joined" with other components "intervened." Here, the other components may be included in one or more of the two or more components that are "connected," "combined," or "joined" with one another.

[0016] In describing the temporal flow relationship regarding components, methods of operation, or methods of production, for example, when the temporal or sequential relationship is described using "after," "following," "next," or "before," it may include cases where the relationship is not continuous unless "immediately" or "directly" is used.

[0017] Meanwhile, where numerical values ​​or corresponding information regarding a component (e.g., levels, etc.) are mentioned, even without separate explicit notation, the numerical values ​​or corresponding information may be interpreted as including a range of error that may occur due to various factors (e.g., process factors, internal or external shocks, noise, etc.).

[0018] A wireless communication system in this specification refers to a system for providing various communication services, such as voice and data packets, using wireless resources, and may include a terminal, a base station, or a core network.

[0019] The embodiments disclosed below may be applied to wireless communication systems using various wireless access technologies. For example, the embodiments may be applied to various wireless access technologies such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), or NOMA (non-orthogonal multiple access). Furthermore, wireless access technology may refer not only to specific access technologies but also to communication technologies for each generation established by various telecommunication organizations such as 3GPP, 3GPP2, WiFi, Bluetooth, IEEE, and ITU. For example, CDMA may be implemented as a wireless technology such as UTRA (universal terrestrial radio access) or CDMA2000. TDMA may be implemented as a wireless technology such as GSM (global system for mobile communications), GPRS (general packet radio service), or EDGE (enhanced datarates for GSM evolution). OFDMA can be implemented using wireless technologies such as IEEE (Institute of Electrical and Electronic Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (evolved UTRA). IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e.UTRA is part of UMTS (universal mobile telecommunications system). 3GPP (3rd generation partnership project) LTE (long term evolution) is part of E-UMTS (evolved UMTS) that uses E-UTRA (evolved-UMTS terrestrial radio access), employing OFDMA in the downlink and SC-FDMA in the uplink. As such, these embodiments can be applied to currently disclosed or commercialized radio access technologies, and can also be applied to radio access technologies currently under development or to be developed in the future.

[0020] Meanwhile, the term "terminal" in this specification is a comprehensive concept meaning a device including a wireless communication module that communicates with a base station in a wireless communication system. It should be interpreted as a concept that includes not only User Equipment (UE) in WCDMA, LTE, NR, HSPA, and IMT-2020 (5G or New Radio), but also Mobile Station (MS), User Terminal (UT), Subscriber Station (SS), and wireless device in GSM. Furthermore, depending on the usage type, the terminal may be a user portable device such as a smartphone, or in a V2X communication system, it may refer to a vehicle or a device including a wireless communication module inside a vehicle. Additionally, in the case of a Machine Type Communication (MMC) system, it may refer to an MTC terminal, M2M terminal, URLLC terminal, etc., equipped with a communication module to perform machine type communication.

[0021] In this specification, "base station" or "cell" refers to an end that communicates with a terminal in terms of a network, and encompasses various coverage areas such as Node-B, eNB (evolved Node-B), gNB (gNode-B), LPN (Low Power Node), Sector, Site, various types of antennas, BTS (Base Transceiver System), Access Point, Point (e.g., Transmitter Point, Receiver Point, Transceiver Point), Relay Node, Mega Cell, Macro Cell, Micro Cell, Pico Cell, Femto Cell, RRH (Remote Radio Head), RU (Radio Unit), and Small Cell. Additionally, "cell" may include a Bandwidth Part (BWP) in the frequency domain. For example, a serving cell may refer to the Activation BWP of a terminal.

[0022] Since there is a base station controlling one or more of the various cells listed above, the term "base station" can be interpreted in two senses. 1) It may refer to the device itself that provides a mega cell, macro cell, micro cell, pico cell, femto cell, or small cell in relation to a wireless area, or 2) it may refer to the wireless area itself. In 1), all devices that provide a specific wireless area are controlled by the same entity or interact to configure the wireless area collaboratively are referred to as base stations. Depending on the configuration method of the wireless area, a point, a transmitting / receiving point, a transmitting point, a receiving point, etc., are examples of a base station. In 2), the wireless area itself that receives or transmits a signal from the perspective of a user terminal or from the perspective of a neighboring base station may also be referred to as a base station.

[0023] In this specification, "Cell" may refer to a component carrier having coverage of a signal transmitted from a transmitting / receiving point or coverage of a signal transmitted from a transmitting / receiving point (transmission point or transmission / reception point), or the transmitting / receiving point itself.

[0024] Uplink (UL, or Uplink) refers to the method of transmitting and receiving data from a terminal to a base station, and Downlink (DL, or Downlink) refers to the method of transmitting and receiving data from a base station to a terminal. Downlink may refer to communication or a communication path from multiple transmission and reception points to a terminal, and uplink may refer to communication or a communication path from a terminal to multiple transmission and reception points. In this case, in the downlink, the transmitter may be part of the multiple transmission and reception points, and the receiver may be part of the terminal. Additionally, in the uplink, the transmitter may be part of the terminal, and the receiver may be part of the multiple transmission and reception points.

[0025] The uplink and downlink transmit and receive control information through control channels such as PDCCH (Physical Downlink Control Channel) and PUCCH (Physical Uplink Control Channel), and transmit and receive data by configuring data channels such as PDSCH (Physical Downlink Shared Channel) and PUSCH (Physical Uplink Shared Channel). In the following, the situation in which signals are transmitted and received through channels such as PUCCH, PUSCH, PDCCH, and PDSCH is also indicated in the form of "transmitting and receiving PUCCH, PUSCH, PDCCH, and PDSCH."

[0026] To clarify the explanation, the technical concept described below is primarily based on 3GPP LTE / LTE-A / NR (New RAT) communication systems, but the technical features are not limited to said communication systems.

[0027] Following research on 4G (4th-Generation) communication technology, 3GPP develops 5G (5th-Generation) communication technology to meet the requirements of the ITU-R for next-generation radio access technology. Specifically, 3GPP develops LTE-A pro, which enhances LTE-Advanced technology to meet ITU-R requirements, and NR, a new communication technology distinct from 4G communication technology, as 5G communication technologies. Since both LTE-A pro and NR refer to 5G communication technology, the following explanation of 5G communication technology will focus on NR unless a specific technology is being identified.

[0028] The operational scenarios in NR define various operation scenarios by adding considerations for satellites, automobiles, and new verticals to the existing 4G LTE scenarios, and in terms of service, they support eMBB (Enhanced Mobile Broadband) scenarios, mMTC (Massive Machine Communication) scenarios which require low data rates and asynchronous access while having high terminal density and being deployed over a wide range, and URLLC (Ultra Reliability and Low Latency) scenarios which require high responsiveness and reliability and can support high-speed mobility.

[0029] To satisfy these scenarios, NR introduces a wireless communication system equipped with new waveform and frame structure technologies, low latency technology, mmWave support technology, and forward compatibility technology. In particular, the NR system presents various technical changes in terms of flexibility to provide forward compatibility. The main technical features of NR are explained below with reference to the drawings.

[0030] <NR 시스템 일반>

[0031] FIG. 1 is a diagram briefly illustrating the structure of an NR system to which the present embodiment can be applied.

[0032] Referring to FIG. 1, the NR system is divided into a 5G Core Network (5GC) and an NR-RAN part. The NG-RAN consists of gNBs and ng-eNBs that provide control plane (RRC) protocol endpoints for the user plane (SDAP / PDCP / RLC / MAC / PHY) and User Equipment (UE). gNBs are interconnected with each other, or gNBs and ng-eNBs are interconnected via Xn interfaces. Each gNB and ng-eNB is connected to the 5GC via an NG interface. The 5GC may be configured to include an Access and Mobility Management Function (AMF), which is responsible for control plane functions such as terminal access and mobility control, and a User Plane Function (UPF), which is responsible for control functions for user data. The NR includes support for both frequency bands below 6 GHz (FR1, Frequency Range 1) and frequency bands above 6 GHz (FR2, Frequency Range 2).

[0033] gNB refers to a base station that provides NR user plane and control plane protocol terminations to a terminal, and ng-eNB refers to a base station that provides E-UTRA user plane and control plane protocol terminations to a terminal. The base station described in this specification should be understood as encompassing both gNB and ng-eNB, and may be used to refer to gNB or ng-eNB separately as needed.

[0034] <NR 웨이브 폼,뉴머롤러지 및 프레임 구조>

[0035] In NR, CP-OFDM waveforms using a cyclic prefix are used for downlink transmission, and CP-OFDM or DFT-s-OFDM are used for uplink transmission. OFDM technology is easy to combine with MIMO (Multiple Input Multiple Output) and has the advantage of allowing the use of low-complexity receivers along with high frequency efficiency.

[0036] Meanwhile, in NR, since the requirements for data rate, latency, coverage, etc. differ for each of the three scenarios mentioned above, it is necessary to efficiently satisfy the requirements for each scenario through the frequency bands that constitute an arbitrary NR system. To this end, a technology has been proposed to efficiently multiplex wireless resources based on multiple different numerologies.

[0037] Specifically, the NR transmission numerator is determined based on sub-carrier spacing and CP (Cyclic prefix), and as shown in Table 1 below, the μ value is used as an exponential value of 2 based on 15 kHz and changes exponentially.

[0038] μ Subcarrier spacing Cyclic prefix Supported for data Supported for synch 0 15 Normal Yes Yes 1 30 Normal Yes Yes 2 60 Normal, Extended Yes No 3 120 Normal Yes Yes 4 240 Normal No Yes

[0039] As shown in Table 1 above, the numerators of NR can be classified into five types based on the subcarrier spacing. This differs from LTE, one of the 4G communication technologies, where the subcarrier spacing is fixed at 15 kHz. Specifically, the subcarrier spacings used for data transmission in NR are 15, 30, 60, and 120 kHz, while the subcarrier spacings used for synchronization signal transmission are 15, 30, 120, and 240 kHz. Additionally, extended CP is applied only to the 60 kHz subcarrier spacing. Meanwhile, the frame structure in NR defines a frame with a length of 10 ms, composed of 10 subframes of equal length of 1 ms. A single frame can be divided into 5 ms half-frames, and each half-frame contains 5 subframes. In the case of a 15 kHz subcarrier interval, one subframe consists of one slot, and each slot consists of 14 OFDM symbols. FIG. 2 is a diagram illustrating the frame structure in an NR system to which the present embodiment can be applied. Referring to FIG. 2, in the case of a normal CP, the slot is fixedly composed of 14 OFDM symbols, but the length of the slot in the time domain may vary depending on the subcarrier interval. For example, in the case of a numeral with a 15 kHz subcarrier interval, the slot is composed of a length of 1 ms, which is the same length as the subframe. In contrast, in the case of a numeral with a 30 kHz subcarrier interval, the slot is composed of 14 OFDM symbols, but two slots may be included in one subframe with a length of 0.5 ms. That is, the subframe and the frame are defined with a fixed time length, while the slot is defined by the number of symbols, and the time length may vary depending on the subcarrier interval.

[0040] Meanwhile, NR defines the basic unit of scheduling as a slot and introduced mini-slots (or sub-slots or non-slot based schedules) to reduce transmission delay in the wireless section. Using a wide subcarrier spacing reduces transmission delay in the wireless section because the length of a single slot becomes inversely shorter. Mini-slots (or sub-slots) are designed for efficient support of URLLC scenarios and allow scheduling in units of 2, 4, or 7 symbols.

[0041] Furthermore, unlike LTE, NR defines uplink and downlink resource allocation at the symbol level within a single slot. To reduce HARQ latency, a slot structure was defined that allows HARQ ACK / NACK to be transmitted directly within the transmission slot; this slot structure is described as a self-contained structure.

[0042] NR is designed to support a total of 256 slot formats, of which 62 are used in 3GPP Rel-15. Additionally, it supports common frame structures that form FDD or TDD frames through various slot combinations. For example, it supports slot structures where all slot symbols are set to downlink, slot structures where all symbols are set to uplink, and slot structures where downlink and uplink symbols are combined. Furthermore, NR supports data transmission being distributed and scheduled across one or more slots. Therefore, base stations can use a Slot Format Indicator (SFI) to inform a terminal whether a slot is a downlink slot, an uplink slot, or a flexible slot. Base stations can indicate the slot format by using the SFI to indicate an index of a table configured via UE-specific RRC signaling, or they can indicate it dynamically via Downlink Control Information (DCI) or statically or semi-statically via RRC.

[0043] <NR 물리 자원 >

[0044] Regarding physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, and bandwidth parts are considered.

[0045] An antenna port is defined such that the channel carrying a symbol on the antenna port can be inferred from the channel carrying another symbol on the same antenna port. If the large-scale property of the channel carrying a symbol on one antenna port can be inferred from the channel carrying a symbol on another antenna port, the two antenna ports can be said to be in a QC / QCL (quasi-co-located or quasi-co-location) relationship. Here, the large-scale property includes one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

[0046] FIG. 3 is a diagram illustrating a resource grid supported by wireless access technology to which the present embodiment can be applied.

[0047] Referring to FIG. 3, a resource grid may exist for each numerator because NR supports multiple numerators on the same carrier. Additionally, a resource grid may exist depending on the antenna port, subcarrier spacing, and transmission direction.

[0048] A resource block consists of 12 subcarriers and is defined only in the frequency domain. Additionally, a resource element consists of one OFDM symbol and one subcarrier. Therefore, as shown in Fig. 3, the size of a single resource block can vary depending on the subcarrier spacing. Furthermore, NR defines "Point A," which serves as a common reference point for the resource block grid, as well as common resource blocks, virtual resource blocks, etc.

[0049] FIG. 4 is a diagram illustrating the bandwidth part supported by the wireless access technology to which the present embodiment can be applied.

[0050] In NR, unlike LTE where the carrier bandwidth is fixed at 20 MHz, the maximum carrier bandwidth is set from 50 MHz to 400 MHz depending on the subcarrier interval. Therefore, it is not assumed that all terminals use this entire carrier bandwidth. Accordingly, in NR, as shown in Fig. 4, a Bandwidth Part (BWP) can be designated within the carrier bandwidth for the terminal to use. Additionally, a Bandwidth Part is associated with a single numerator and consists of a subset of a continuous common resource block, and can be dynamically activated over time. Up to four Bandwidth Parts are configured for the uplink and downlink respectively, and data is transmitted and received using the Bandwidth Part activated at a given time.

[0051] In the case of paired spectrum, the uplink and downlink bandwidth parts are set independently, whereas in the case of unpaired spectrum, the downlink and uplink bandwidth parts are paired to share a center frequency in order to prevent unnecessary frequency re-tuning between downlink and uplink operations.

[0052] <NR 초기 접속>

[0053] In NR, the terminal performs cell search and random access procedures to connect to the base station and perform communication.

[0054] Cell search is a procedure in which a terminal uses a Synchronization Signal Block (SSB) transmitted by a base station to synchronize with the corresponding base station's cell, obtain a physical layer cell ID, and acquire system information.

[0055] FIG. 5 is a diagram illustrating an exemplary synchronization signal block in a wireless access technology to which the present embodiment can be applied.

[0056] Referring to FIG. 5, the SSB consists of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) each occupying 1 symbol and 127 subcarriers, and a PBCH spanning 3 OFDM symbols and 240 subcarriers.

[0057] The terminal monitors the SSB in the time and frequency domains and receives the SSB.

[0058] SSBs can be transmitted up to 64 times within 5ms. Multiple SSBs are transmitted via different transmission beams within the 5ms timeframe, and the terminal performs detection by assuming that an SSB is transmitted every 20ms when viewed from the perspective of a specific beam used for transmission. The number of beams available for SSB transmission within the 5ms timeframe can increase as the frequency band increases. For example, up to 4 SSB beams can be transmitted at 3GHz or lower, up to 8 beams in the frequency band from 3GHz to 6GHz, and up to 64 different beams can be used to transmit SSBs in the frequency band above 6GHz.

[0059] Two SSBs are included in a single slot, and the starting symbol and number of repetitions within the slot are determined according to the subcarrier interval as follows.

[0060] Meanwhile, unlike the SS of conventional LTE, the SSB is not transmitted at the center frequency of the carrier bandwidth. That is, the SSB can be transmitted even at locations other than the center of the system band, and multiple SSBs can be transmitted across the frequency domain when broadband operation is supported. Accordingly, the terminal monitors the SSB using a synchronization raster, which is a candidate frequency location for monitoring the SSB. The carrier raster, which is information on the center frequency location of the channel for initial connection, and the synchronization raster were newly defined in NR, and the synchronization raster is set with a wider frequency interval compared to the carrier raster, thereby supporting fast SSB search by the terminal.

[0061] The terminal can obtain the MIB through the SSB's PBCH. The Master Information Block (MIB) contains minimum information for the terminal to receive the Remaining Minimum System Information (RMSI) broadcast by the network. Additionally, the PBCH may include information regarding the location of the first DM-RS symbol in the time domain, information for the terminal to monitor SIB1 (e.g., SIB1 numeral information, information related to SIB1 CORESET, search space information, PDCCH related parameter information, etc.), and offset information between the Common Resource Block and the SSB (the absolute location of the SSB within the carrier is transmitted via SIB1). Here, the SIB1 numeral information is applied identically to some messages used in the random access procedure for the terminal to connect to the base station after completing the cell search procedure. For example, the SIB1 numeral information may be applied to at least one of messages 1 to 4 for the random access procedure.

[0062] The aforementioned RMSI may refer to SIB1 (System Information Block 1), and SIB1 is broadcast periodically (e.g., 160ms) from the cell. SIB1 contains information necessary for the terminal to perform the initial random access procedure and is transmitted periodically via PDSCH. To receive SIB1, the terminal must receive the numerology information used for transmitting SIB1 and the CORESET (Control Resource Set) information used for scheduling SIB1 via PBCH. The terminal checks the scheduling information for SIB1 using SI-RNTI within the CORESET and obtains SIB1 on the PDSCH according to the scheduling information. The remaining SIBs, excluding SIB1, may be transmitted periodically or upon the terminal's request.

[0063] FIG. 6 is a diagram illustrating a random access procedure in a wireless access technology to which the present embodiment can be applied.

[0064] Referring to FIG. 6, when cell search is completed, the terminal transmits a random access preamble for random access to the base station. The random access preamble is transmitted via PRACH. Specifically, the random access preamble is transmitted to the base station via PRACH, which consists of a series of radio resources in specific slots that are repeated periodically. Generally, when the terminal initially connects to a cell, a contention-based random access procedure is performed, and when performing random access for Beam Failure Recovery (BFR), a non-contention-based random access procedure is performed.

[0065] The terminal receives a random access response for the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), an UL Grant (uplink radio resource), a temporary C-RNTI (Temporary Cell - Radio Network Temporary Identifier), and a TAC (Time Alignment Command). Since a single random access response may contain random access response information for one or more terminals, the random access preamble identifier may be included to indicate which terminal the included UL Grant, temporary C-RNTI, and TAC are valid for. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the terminal to coordinate uplink synchronization. The random access response may be indicated by the random access identifier on the PDCCH, namely the RA-RNTI (Random Access - Radio Network Temporary Identifier).

[0066] A terminal that receives a valid random access response processes the information contained in the random access response and performs a transmission scheduled to the base station. For example, the terminal applies a TAC and stores a temporary C-RNTI. Additionally, using a UL Grant, it transmits data stored in the terminal's buffer or newly generated data to the base station. In this case, information that can identify the terminal must be included.

[0067] Finally, the terminal receives a downlink message to resolve competition.

[0068] <NR CORESET>

[0069] The downlink control channel in NR is transmitted in a CORESET (Control Resource Set) with a length of 1 to 3 symbols, and transmits uplink / downlink scheduling information, SFI (Slot format Index), TPC (Transmit Power Control) information, etc.

[0070] In this way, NR introduced the concept of CORESET to ensure system flexibility. CORESET (Control Resource Set) refers to time-frequency resources for downlink control signals. A terminal can decode control channel candidates by using one or more search spaces from the CORESET time-frequency resources. Quasi CoLocation (QCL) assumptions were established for each CORESET, and these are used to indicate characteristics regarding the analog beam direction in addition to the characteristics assumed by conventional QCL, such as delay spread, Doppler spread, Doppler shift, and mean delay.

[0071] Figure 7 is a diagram for explaining CORESET.

[0072] Referring to FIG. 7, CORESET can exist in various forms within a single slot and within the carrier bandwidth, and in the time domain, CORESET can be composed of up to 3 OFDM symbols. Additionally, CORESET is defined as a multiple of 6 resource blocks up to the carrier bandwidth in the frequency domain.

[0073] The first CORESET is specified via the MIB as part of the initial bandwidth part configuration to enable the reception of additional configuration and system information from the network. After establishing a connection with the base station, the terminal can be configured by receiving one or more CORESET information via RRC signaling.

[0074] In this specification, frequencies, frames, subframes, resources, resource blocks, regions, bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals, or various messages related to NR (New Radio) may be interpreted in the sense used in the past or present, or in various senses used in the future.

[0075] NR (New Radio)

[0076] NR, a next-generation wireless communication technology currently undergoing standardization by 3GPP, is a wireless access technology that provides enhanced data transmission rates compared to LTE and can satisfy various QoS requirements for detailed and specific usage scenarios. In particular, eMBB (Enhancement Mobile BroadBand), mMTC (Massive MTC), and URLLC (Ultra Reliable and Low Latency Communications) have been defined as representative usage scenarios for NR. As a method to satisfy the requirements of each scenario, a flexible frame structure compared to LTE is provided. The frame structure of NR supports a multiple subcarrier-based frame structure. The default Subcarrier Spacing (SCS) is 15 kHz, and a total of five types of SCS are supported as 15 kHz * 2^n.

[0077] Figure 8 is a diagram showing an example of different subcarrier spacings aligned at the symbol level.

[0078] Referring to Fig. 8, it can be seen that the time axis length of the slot varies according to the numerology. That is, it can be seen that as the slot length becomes shorter, the SCS becomes larger. In addition, the number of OFDM symbols constituting the slot in NR, the y value, is fixed to y=14 regardless of the SCS value in the case of normal CP. Accordingly, any slot consists of 14 symbols. Furthermore, depending on the transmission direction of the slot, all symbols may be used for DL ​​transmission, all symbols may be used for UL transmission, or they may be used in the form of DL portion + (gap) + UL portion.

[0079] In addition, a mini-slot consisting of fewer symbols than the aforementioned slot is defined in any numerology (or SCS). A short time-domain scheduling interval for uplink / downlink data transmission and reception based on the mini-slot can be set, or a long time-domain scheduling interval for uplink / downlink data transmission and reception can be configured through slot aggregation. In particular, when transmitting and receiving latency-sensitive data such as URLLC, it may be difficult to satisfy latency requirements if slot-unit scheduling based on 1ms (14 symbols) is performed in a frame structure based on a numerology with a small SCS value, such as 15kHz. Therefore, a mini-slot consisting of fewer OFDM symbols than the slot consisting of 14 symbols can be defined, and scheduling that satisfies the requirements of URLLC can be performed based on this.

[0080] NR supports the following structure in the time axis. The difference from existing LTE is that in NR, the basic scheduling unit has been changed to the aforementioned slot. In addition, regardless of subcarrier spacing, the slot consists of 14 OFDM symbols as shown in Fig. 9. On the other hand, it supports a non-slot structure (mini-slot structure) consisting of 2, 4, and 7 OFDM symbols, which is a smaller scheduling unit. The non-slot structure can be utilized as a scheduling unit for URLLC services.

[0081] ■ Radio frame: Fixed 10ms regardless of numerology (SCS).

[0082] ■ Subframe: Fixed to 1ms in the time domain (Fixed 1ms as a reference for time duration). Unlike LTE, it is not used as a scheduling unit for data and control signals.

[0083] ■ Slot: Mainly used for eMBB scenarios. Includes 14 OFDM symbols.

[0084] ■ Non-slot (i.e., mini-slot): Mainly used for URLLC scenarios, but not limited to URLLC. Includes 2, 4, or 7 OFDM symbols.

[0085] ■ One TTI duration: A time duration for data / control channel transmission. A number of OFDM symbols per slot / non-slot in the time axis.

[0086] <NR MIMO 및 Beam 운영>

[0087] In NR, beam management technology, which is an evolutionary technology of analog beamforming, was added, and MIMO codebook / feedback technology, a conventional digital beamforming technology, was advanced.

[0088] In the case of analog beamforming, it can be broadly classified into beam operation-related technologies that form optimal beam pairs between a base station and a terminal through base station / terminal beam sweeping transmission and beam iteration transmission, and beam failure recovery techniques designed to quickly overcome quality degradation of the serving beam in use and form new beam pairs.

[0089] initial beam establishment

[0090] The procedure for forming the best beam pair between the initial base station and the terminal, namely initial beam establishment, takes place during the initial connection procedure. During the initial cell search, the terminal can acquire some of a plurality of SSBs, each consisting of different downlink beams transmitted from the base station, in chronological order.

[0091] The terminal selects an optimal beam based on the acquired SSBs and transmits a random access preamble associated with this optimal beam to the base station. Specifically, different SSB time indices are associated with different RACH time / frequency occasions and / or different preamble sequences.

[0092] When a single SSB is associated with two or more random access time / frequency occupations, the priority is as follows: frequency has the highest priority, time has the next highest priority within a single slot, and time has the highest priority between two slots.

[0093] Therefore, the base station can identify the optimal beam through the random access preamble associated with the optimal beam. As a result, the base station and the terminal form an initial optimal beam pair.

[0094] Beam adjustment

[0095] Since relatively wide beams were used during the initial beamforming, the base station and the terminal perform beam adaptation to a relatively narrow beam after the initial beamforming. Additionally, beam adaptation is performed even when the terminal moves or rotates.

[0096] Beam adaptation can be divided into downlink beam adaptation and uplink beam adaptation.

[0097] Downlink beam adjustment can be divided into downlink transmitter-side beam adjustment and downlink receiver-side beam adjustment.

[0098] For example, downlink transmitter beam adaptation is explained. When a base station transmits two or more downlink signals (e.g., CSI-RS or SSB), the terminal performs measurements on them and reports the results to the base station. Based on the results reported by the terminal, the base station determines the optimal beam, and the base station and the terminal form a beam pair based on that optimal beam.

[0099] When a base station and a terminal form a beam pair using CSI-RS, the base station sequentially transmits at least two and up to four CSI-RSs, each composed of different beams, to the terminal. The terminal measures each CSI-RS, for example, L1-RSRP, and reports the results to the base station. The reported results may include indication information for up to four CSI-RSs, the measured L1-RSRP for the strongest beam, and the difference between the L1-RSRP of the remaining beams and the L1-RSRP of the strongest beam.

[0100] Beam Indication and TCI

[0101] NR supports beam indication functions. For example, the base station informs the terminal of the beams used in the PDSCH and PDCCH using configuration information and the TCI (Transmission Configuration Indicator).

[0102] For example, a terminal can be configured with up to 64 candidate TCI states. For PDCCH beam indication, a subset of the M configured candidate TCI states is assigned by upper layer signaling, e.g., RRC signaling, and the base station dynamically indicates a specific TCI state by MAC signaling.

[0103] For PDSCH beam indication, if the PDCCH-PDSCH scheduling offset included in the PDCCH is greater than N symbols, the scheduling allocation DCI (e.g., 3 bits) explicitly indicates the TCI state for PDSCH transmission. If the PDCCH-PDSCH scheduling offset included in the PDCCH is equal to or less than N symbols, the terminal assumes that the TCI state of the PDCCH indicated by MAC signaling as described above is the same as the TCI state for PDSCH transmission.

[0104] NR measurement

[0105] FIG. 9 is a diagram illustrating a cell measurement model in NR to which the present embodiment can be applied.

[0106] Referring to Fig. 9, in an RRC connection state, the terminal measures multiple beams of a cell, and the measurement results are averaged to derive cell quality. By doing so, the terminal is configured to consider a subset of the detected beams. Filtering occurs at two different levels: first at the physical layer to derive beam quality, and second at the RRC layer to derive cell quality from multiple beams. For serving cells and non-serving cells, cell quality is derived from beam measurements in the same way. The base station can configure the terminal to include the measurement results of the X best beam in the measurement report. Intra-frequency neighbor (cell) measurements and inter-frequency neighbor (cell) measurements are defined as follows.

[0107] - SSB-based intra-frequency measurement: A measurement is defined as an SSB-based intra-frequency measurement provided the center frequency of the SSB of the serving cell and the center frequency of the SSB of the neighbor cell are the same, and the subcarrier spacing of the two SSBs is also the same.

[0108] - SSB-based inter-frequency measurement: A measurement is defined as an SSB-based inter-frequency measurement provided the center frequency of the SSB of the serving cell and the center frequency of the SSB of the neighbor cell are different, or the subcarrier spacing of the two SSBs is different.

[0109] - CSI-RS based intra-frequency measurement: A measurement is defined as a CSI-RS based intra-frequency measurement provided the bandwidth of the CSI-RS resource on the neighbor cell configured for measurement is within the bandwidth of the CSI-RS resource on the serving cell configured for measurement, and the subcarrier spacing of the two CSI-RS resources is the same.

[0110] - CSI-RS based inter-frequency measurement: A measurement is defined as a CSI-RS based inter-frequency measurement provided the bandwidth of the CSI-RS resource on the neighbor cell configured for measurement is not within the bandwidth of the CSI-RS resource on the serving cell configured for measurement, or the subcarrier spacing of the two CSI-RS resources is different.

[0111] Non-Terrestrial Network (NTN)

[0112] A non-terrestrial network refers to a network or segment of a network that uses airborne vehicles such as High Altitude Platforms (HAPS) or spaceborne vehicles such as satellites.

[0113] ● Spaceborne vehicles: Satellites (may include Low Earth Orbiting (LEO) satellites, Medium Earth Orbiting (MEO) satellites, Geostationary Earth Orbiting (GEO) satellites as well as Highly Elliptical Orbiting (HEO) satellites.)

[0114] ● Airborne vehicles: High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) including Lighter than Air UAS (LTA), Heavier than Air UAS (HTA), all operating in altitudes typically between 8 and 50 km, quasi-stationary

[0115] 3GPP is developing technologies to support NR operations in non-terrestrial networks utilizing the aforementioned satellites or air transport vehicles. However, in non-terrestrial networks, the distance between a base station and a terminal is longer than in terrestrial networks utilizing ground base stations. Consequently, very large Round Trip Delay (RTD) may occur. For example, it is known that in an NTN scenario using GEO located at an altitude of 35,768 km, the RTD is 544.751 ms, and in an NTN scenario using HAPS located at an altitude of 229 km, the RTD is 3.053 ms. Furthermore, in an NTN scenario utilizing LEO satellite systems, the RTD can reach up to 25.76 ms. As such, to perform communication operations where NR protocols are applied in non-terrestrial networks, technology is required to support the base station and the terminal in performing NR operations even under such propagation delays.

[0116] FIG. 10 is a diagram illustrating an exemplary NTN scenario to which the present embodiment can be applied.

[0117] Referring to Fig. 10, NTN can be implemented in various ways as follows.

[0118] -Scenario A: Transparent GEO (NTN beam foot print fixed on earth)

[0119] -Scenario B: Regenerative GEO (NTN beam foot print fixed on earth)

[0120] -Scenario C1: Transparent LEO (NTN beam foot print fixed on earth)

[0121] -Scenario C2: Transparent LEO (NTN beam foot print moving on earth)

[0122] -Scenario D1: Regenerative LEO (NTN beam foot print fixed on earth)

[0123] -Scenario D2: Regenerative LEO (NTN beam foot print moving on earth)

[0124] 여기서 transparent payload 또는 regenerative payload는 다음과 같이 정의된다.

[0125] - A transparent payload: Radio Frequency filtering, Frequency conversion and amplification. Hence, the waveform signal repeated by the payload is un-changed;

[0126] - A regenerative payload: Radio Frequency filtering, Frequency conversion and amplification as well as demodulation / decoding, switch and / or routing, coding / modulation. This is effectively equivalent to having all or part of base station functions (eg gNB) on board the satellite (or UAS platform).

[0127] As shown in Fig. 10, the beams generated by the satellite generate several beams over a given service area bounded by the satellite's field of view. The ground reception footprint of the beams is typically elliptical.

[0128] FIG. 11 is a diagram illustrating the types of NTN platforms to which the present embodiment can be applied.

[0129] Referring to Figure 11, typical beam footprint sizes by type of NTN platform are shown. For example, LEO satellites have beam sizes in the range of 100-500 km, and each satellite and UAS platform may have different beam sizes depending on the operating altitude range and orbit.

[0130] Meanwhile, as in scenarios C2 and D2, when the NTN beam footprint moves on Earth—that is, when the satellite beam moves along with the satellite—it can be assumed that the linkage between the cell and the base station does not change. For example, when the satellite beam transmitted through the corresponding satellite is configured to be linked one-to-one with a single PCI, the cell possessing that PCI moves on Earth as time passes.

[0131] For the sake of convenience of explanation, beams generated from satellite platforms in NTN will be referred to as "satellite beams" below. This is for explanatory purposes only and may be replaced by any other term; it refers to a communication coverage area of ​​a specific radius generated by a network node of a non-terrestrial network for communication purposes.

[0132] On the other hand, an earth fixed beam, used in other scenarios, means that the satellite steers the beam to a fixed point on Earth using beamforming techniques during its visibility time. In the case of a steerable beam like this, the satellite beam's footprint can remain fixed on Earth for a certain period of time even if the satellite moves.

[0133] In cases where the satellite beam moves along with the satellite on Earth or in the case of an earth-fixed beam, a terminal connected to the RRC may need to perform a handover due to changes in the satellite beam even if the terminal is not moving, depending on the movement of the satellite. For example, since the speed of LEO satellites is very fast at 7.56 km / sec, handovers must be performed frequently even if the terminal is not moving. Consequently, the overhead of measurement and reporting by the terminal increases due to frequent handover operations.

[0134] As such, in non-terrestrial networks where satellite beams move on Earth, handovers due to cell changes can be triggered even if the terminal does not move. Consequently, there is a problem of increased measurement and reporting overhead for the terminal. To solve this problem, the present disclosure proposes a specific method and apparatus for efficiently providing a measurement procedure for a terminal serviced through a non-terrestrial network.

[0135] Conventional NR specifications do not provide an explicit definition of a single cell. However, Physical Cell Identifiers (PCIs) are used in NR specifications. Multiple SSBs can be transmitted within a single carrier frequency span. The PCIs of these SSBs do not need to be unique. However, when a single SSB is associated with a single RMSI, that SSB corresponds to a single individual cell possessing a unique NR cell global identifier. Such an SSB is referred to as a Cell-Defining SSB (CD-SSB). (Within the frequency span of a carrier, multiple SSBs can be transmitted. The PCIs of those SSBs do not have to be unique; that is, different SSBs can have different PCIs. However, when an SSB is associated with an RMSI, the SSB corresponds to an individual cell, which has a unique NCGI. Such an SSB is referred to as a Cell-Defining SSB (CD-SSB). A PCell is always associated with a CD-SSB located on the synchronization raster.) From the terminal's perspective, each serving cell is associated with at most a single SSB. In conventional NR standards, SSBs were serviced by physical beams through which NR-PSS, NR-SSS, and NR-PBCH were transmitted, and multiple SSBs within a single cell shared the same PCI. Additionally, SSBs were transmitted in a TDM manner via beam sweeping.

[0136] A single satellite beam is a single beam generated from a single satellite platform, and a single earth footprint or wireless coverage is formed by a single satellite beam. For example, the wireless coverage can be an area capable of receiving a signal with a value greater than a certain threshold from the beam's strongest signal. In order to provide NTN efficiently by maximizing the reuse of NR specifications, it is assumed that the terminal does not consider distinguishing between a satellite beam, a satellite, or a satellite cell that is distinct from an NR cell.

[0137] FIG. 12 is a diagram illustrating an exemplary configuration of an NTN satellite beam to which the present embodiment can be applied.

[0138] Referring to Fig. 12, we examine an example of satellite beam configuration when constructing an NTN based on NR. First, as in option a, the same PCI can be configured to be set for multiple (e.g., L) satellite beams. The linkage between the PCI and the SSB can be implemented in a manner similar to NR. For example, one SSB can be provided for each PCI. Alternatively, multiple SSBs can be provided for a single PCI. Multiple SSBs can be provided via a single satellite beam using the TDM method. This allows for beam mobility to be provided by distinguishing satellite beams while they share the same cell identification information. On the other hand, since NTN involves significant latency between the terminal and the satellite, the effectiveness of using multiple SSBs via the TDM method may be limited. Therefore, if multiple SSBs are provided for the same PCI, they can be configured to have different satellite beams with different SSBs by providing them via the FDM method. In this case, for satellite beams providing different SSBs for the same PCI, one or more information elements can be provided through different MIB information and different SIB1 to distinguish their respective frequencies. This allows for the provision of beam mobility by distinguishing satellite beams that have the same Cell Identification Information (PCI). Alternatively, satellite beams providing different SSBs for the same PCI may have one or more information elements that share the same MIB information, but may be provided through SIB1s that differ in one or more information elements.

[0139] NR SIB1 includes cell selection information (cellSelectionInfo) for selecting a serving cell, cell access related information (CellAccessRelatedInfo) including PLMN ID, information for controlling connection setup failure (ConnEstFailureControl), scheduling information for system information (si-SchedulingInfo), serving cell common configuration information (servingCellConfigCommon), integrated access barring information (uac-BarringInfo), information for supporting IMS emergency bearer service (ims-EmergencySupport), and information on timers and constant values ​​to be used by the terminal (ue-TimersAndConstants). Among these, the serving cell common configuration information includes PCI, downlink common configuration information (downlinkConfigCommon), uplink common configuration information (uplinkConfigCommon), etc. Downlink common configuration information includes downlink frequency information (frequencyInfoDL) and initial downlink BWP (initialDownlinkBWP) information, and uplink common configuration information includes uplink frequency information (frequencyInfoUL) and initial uplink BWP (initialuplinkBWP) information. Satellite beams providing different SSBs for the same PCI have the same MIB information, but can be provided by including individual SIB information elements (e.g., downlink frequency information, uplink frequency information) for each satellite beam providing an SSB.

[0140] Alternatively, satellite beams providing different SSBs for the same PCI may have one or more information elements provided through the same MIB and the same SIB1. Or, satellite beams providing different SSBs for the same PCI may have one or more information elements with different MIB information but provide the same SIB1.

[0141] As another example, such as option b, it may be configured so that each satellite beam has one PCI. Since the coverage of NTN is larger than that of high-frequency-based terrestrial NR, it is not necessary to provide multiple SSBs for the same PCI. Therefore, one satellite beam can be configured as one cell. This allows different satellite beams to be configured to have different PCIs (or NGCIs). The linkage between PCIs and SSBs can be implemented in a manner similar to NR. For example, one SSB may be provided for each PCI. Or, multiple SSBs may be provided for a single PCI. Multiple SSBs may be provided in a TDM manner by a single satellite beam. Although the foregoing description describes examples of linking one PCI to one or multiple SSBs, this is merely for convenience of explanation, and the present disclosure may be applied in any scenario where a single cell is divided into multiple satellite beams with the same PCI for transmission.

[0142] In order to efficiently process the measurement and reporting of terminals serviced through non-terrestrial networks in the various scenarios described above, the embodiments of this specification may be used individually or in any combination.

[0143] In this specification, a base station may refer to an aerial entity, such as a satellite, that transmits and receives information to and from a terminal in an NTN situation. Alternatively, it may refer to a ground entity that generates data transmitted and received through an aerial entity, such as a satellite. That is, in this disclosure, a base station refers to an entity that transmits and receives data with a terminal in an NTN situation, and there are no limitations on the terminology.

[0144] FIG. 13 is a diagram illustrating terminal operation according to one embodiment.

[0145] Referring to FIG. 13, a terminal performing communication using a non-terrestrial network (NTN) may perform the step of receiving configuration information from a base station to control cell measurement or cell measurement reporting in the non-terrestrial network (S1310).

[0146] For example, the configuration information may include at least one of skip duration information for suspending the performance of cell measurement or cell measurement reporting for a certain period, location range information, and terminal movement correction parameter information. As an example, the configuration information may include at least one of a measurement period, threshold value, measurement location, timer value, and neighbor cell information for the terminal to perform a measurement operation on a cell. As another example, the configuration information may include at least one of a measurement report trigger condition, measurement report period, timer value, threshold value, and measurement report location for the terminal to perform a measurement operation on a cell and report the measurement to the base station. In addition, the configuration information may include parameters used by the terminal to measure and report the channel status of one or more cells or beams.

[0147] Meanwhile, as previously mentioned, since frequent handovers may occur when using a non-terrestrial network, information for skipping cell measurements or cell measurement reports may be further included in the configuration information. For example, the configuration information may include skip duration information for the terminal to skip (stop) cell measurements or cell measurement reports for a certain period, a timer value, location range information used to skip location-based cell measurements or cell measurement reports, and terminal movement correction parameter information for correcting the location by considering the terminal's mobility.

[0148] Configuration information may be received by the terminal included in RRC messages or system information. The parameters included in the more specific configuration information and the operation of the terminal using it are explained below in detail by dividing them into specific examples.

[0149] The terminal can perform a step of determining whether to perform cell measurement or cell measurement reporting using configuration information (S1320).

[0150] For example, the terminal determines whether a timer included in the configuration information is running, and if the timer is running, determines that a cell measurement or cell measurement report operation is not performed. For example, the configuration information may include a specific timer or timer value. When a timer start operation is triggered, the terminal starts the timer, and if the timer is running, it may not perform the cell measurement or cell measurement report even if it is triggered. If the timer expires, the terminal monitors whether the cell measurement or cell measurement report is triggered, and if it is triggered, it may perform the cell measurement or cell measurement report operation.

[0151] As another example, the target for determining whether to perform cell measurement or cell measurement reporting may be at least one of the serving cell, intra-frequency band, inter-frequency band, and inter-wireless access technology neighbor cells. That is, the determination of whether to perform cell measurement or cell measurement reporting based on the aforementioned timer operation may be made for all of the serving cell, intra-frequency band, inter-frequency band, and inter-wireless access technology neighbor cells. Alternatively, a different timer may be applied to each cell or measurement target. Or, among each cell or measurement target, a specific target may be designated by the base station, and the determination of whether to perform cell measurement or cell measurement reporting may be made only for the designated cell or measurement target. In this case, the configuration information may further include information regarding the cell or measurement target designated by the base station. Of course, conversely, the target for determining whether to perform cell measurement or cell measurement reporting may be selected excluding the cell or measurement target designated by the base station.

[0152] As mentioned above, positional factors rather than temporal factors may be applied when determining cell measurement or cell measurement reporting. For example, if the terminal is located in a specific area indicated by configuration information, it may be determined that the cell measurement or cell measurement reporting operation is not performed. Conversely, if the terminal is not located in a specific area indicated by configuration information, it may be determined that the cell measurement or cell measurement reporting operation is not performed.

[0153] The terminal may perform a step of controlling cell measurement or cell measurement reporting operations based on the judgment result (S1330).

[0154] For example, if the terminal determines that cell measurement or cell measurement reporting should not be performed by skipping it, it may not perform the cell measurement or cell measurement reporting even if it is triggered. That is, even if a normal cell measurement or cell measurement reporting cycle is reached and the cell measurement or cell measurement reporting is triggered, if it is determined that it should not be performed according to the aforementioned timer or position, the cell measurement or cell measurement reporting operation is not performed during that cycle.

[0155] Through the above operations, the terminal can prevent frequent cell measurement or cell measurement reporting operations, thereby enabling efficient management of processes, power, etc.

[0156] The aforementioned terminal operation is explained in more detail below by dividing it into individual embodiments. The individual embodiments described below may be performed by the terminal by combining all or part of them by any combination.

[0157] FIG. 14 is a diagram illustrating the operation of a base station according to one embodiment.

[0158] Referring to FIG. 14, a base station that performs communication using a non-terrestrial network (NTN) can perform the step of transmitting configuration information to a terminal to control cell measurement or cell measurement reporting in the non-terrestrial network (S1410).

[0159] For example, the configuration information may include at least one of skip duration information for suspending the performance of cell measurement or cell measurement reporting for a certain period, location range information, and terminal movement correction parameter information. As an example, the configuration information may include at least one of a measurement period, threshold value, measurement location, timer value, and neighbor cell information for the terminal to perform a measurement operation on a cell. As another example, the configuration information may include at least one of a measurement report trigger condition, measurement report period, timer value, threshold value, and measurement report location for the terminal to perform a measurement operation on a cell and report the measurement to the base station. In addition, the configuration information may include parameters used by the terminal to measure and report the channel status of one or more cells or beams.

[0160] Additionally, the configuration information may include skip duration information for the terminal to skip (stop) cell measurement or cell measurement reporting for a certain period, a timer value, location range information used to skip location-based cell measurement or cell measurement reporting, and terminal movement correction parameter information for correcting the location by considering the mobility of the terminal.

[0161] Configuration information can be included in RRC messages or system information and transmitted to the terminal.

[0162] The base station may perform the step of receiving a cell measurement report based on the result of determining whether the terminal performs cell measurement or cell measurement reporting using configuration information (S1420).

[0163] For example, the terminal determines whether a timer included in the configuration information is running, and if the timer is running, determines that a cell measurement or cell measurement report operation is not performed. For example, the configuration information may include a specific timer or timer value. When a timer start operation is triggered, the terminal starts the timer, and if the timer is running, it may not perform the cell measurement or cell measurement report even if it is triggered. If the timer expires, the terminal monitors whether the cell measurement or cell measurement report is triggered, and if it is triggered, it may perform the cell measurement or cell measurement report operation.

[0164] As another example, the target for determining whether to perform cell measurement or cell measurement reporting may be at least one of the serving cell, intra-frequency band, inter-frequency band, and inter-wireless access technology neighbor cells. That is, the determination of whether to perform cell measurement or cell measurement reporting based on the aforementioned timer operation may be made for all of the serving cell, intra-frequency band, inter-frequency band, and inter-wireless access technology neighbor cells. Alternatively, a different timer may be applied to each cell or measurement target. Or, among each cell or measurement target, a specific target may be designated by the base station, and the determination of whether to perform cell measurement or cell measurement reporting may be made only for the designated cell or measurement target. In this case, the configuration information may further include information regarding the cell or measurement target designated by the base station. Of course, conversely, the target for determining whether to perform cell measurement or cell measurement reporting may be selected excluding the cell or measurement target designated by the base station.

[0165] As mentioned above, positional factors rather than temporal factors may be applied when determining cell measurement or cell measurement reporting. For example, if the terminal is located in a specific area indicated by configuration information, it may be determined that the cell measurement or cell measurement reporting operation is not performed. Conversely, if the terminal is not located in a specific area indicated by configuration information, it may be determined that the cell measurement or cell measurement reporting operation is not performed.

[0166] The base station receives a cell measurement report from the terminal when the terminal's cell measurement and cell measurement report are triggered and the conditions for executing the terminal's cell measurement report are satisfied. For example, if the terminal determines that the cell measurement or cell measurement report should not be performed by skipping it, it may not perform the cell measurement or cell measurement report even if it is triggered. That is, even if the normal cell measurement or cell measurement report cycle arrives and the cell measurement or cell measurement report is triggered, if it is determined that it should not be performed according to the aforementioned timer or location, the cell measurement or cell measurement report operation is not performed during that cycle.

[0167] Through the above operations, the terminal can prevent frequent cell measurement or cell measurement reporting operations, thereby enabling efficient management of processes, power, etc.

[0168] Below, various operations that the aforementioned terminal and base station can perform are described by distinguishing each embodiment. Each embodiment may be applied individually or by any combination.

[0169] 1) An example of using satellite orbit information to instruct skipping cell measurements within a section where the serving satellite / satellite beam does not change.

[0170] A terminal may be located within coverage generated by a single satellite. Alternatively, the terminal may be located within overlapping coverage generated by multiple satellites. If the terminal is within coverage provided by a single satellite / satellite beam, the terminal may not need to consider changing the satellite / satellite beam / cell during the time period when the corresponding satellite / satellite beam / cell does not change at its current location (location area / zone). Although the radio quality of the relevant satellite / satellite beam / cell may temporarily degrade, if the terminal's location does not change significantly and the satellite / satellite beam / cell covering that location is the only one, it may be preferable to skip cell measurement as there is no need to perform a change of satellite / satellite beam / cell.

[0171] Specifically, cases where a terminal is located within coverage overlapping multiple satellites can be considered in two ways. First is the case where the terminal is located at the boundary or edge of multiple satellites, satellite beams, or cells. When the terminal is located at the boundary or edge of a serving satellite, satellite beam, or cell, a change in satellite, satellite beam, or cell is expected. Therefore, standard cell measurement and measurement reporting operations may be required. On the other hand, even if the terminal is located within coverage overlapping multiple satellites, if the terminal is located in the center of a serving satellite, satellite beam, or cell, there may be no need to perform a change in satellite, satellite beam, or cell, so it may be desirable to skip cell measurement.

[0172] For convenience of explanation, the action of performing to reduce cell measurement or cell measurement report overhead, where it may not be necessary to perform satellite / satellite beam / cell switching as described below, is referred to as a cell measurement skip. This is for convenience of explanation and may be replaced with any other term. For example, a cell measurement skip may indicate that the terminal is not required to perform measurements for intra-frequency, inter-frequency, and inter-RAT neighboring cells. For another example, a cell measurement skip may indicate that the terminal is not required to perform measurements for the serving cell. For yet another example, a cell measurement skip may indicate that the terminal is not required to perform measurements for neighboring cells in one or more of the cases of intra-frequency, inter-frequency, and inter-RAT. For yet another example, a cell measurement skip may indicate that the terminal is not required to perform measurements for the serving cell and neighboring cells. As another example, a cell measurement skip may indicate that the terminal is not required to perform cell measurement reports for intra-frequency, inter-frequency, and inter-RAT neighboring cells. As another example, a cell measurement skip may indicate that the terminal is not required to perform cell measurement reports for the serving cell. As another example, a cell measurement skip may indicate that the terminal is not required to perform cell measurement reports for the serving cell and neighboring cells.

[0173] Cell measurement skip can be applied to RRC connected terminals. Alternatively, cell measurement skip can also be applied to RRC idle or RRC inactive terminals.

[0174] Meanwhile, the base station may transmit the terminal's measurement configuration information (measconfig) or system information, including configuration information for instructing the aforementioned cell measurement skip. Such configuration information may include information for setting up measurement to be performed based on SSB RSRP or CSI-RS RSRP. This will be explained in more detail below.

[0175] Meanwhile, the satellite's orbit information (ephemeris) is publicly available. This includes x, y, and z coordinate information and velocity information in an earth-centered, earth-fixed coordinate system according to time (epoch, which includes year, month, day, hour, and second information). FIG. 15 is a diagram illustrating satellite orbit information according to one embodiment. FIG. 16 is a diagram for explaining the parameter values ​​of satellite orbit information according to one embodiment.

[0176] Referring to FIGS. 15 and 16, the satellite orbit information is information regarding the satellite's orbital trajectories and includes semi-major axis, eccentricity, inclination, right ascension of the ascending node, argument of periapsis, mean anomaly at a reference point in time, and the satellite orbit information reference time (the epoch).

[0177] If a network (or terminal) can utilize satellite orbit information, it can help reduce overhead in measurements and measurement reports for satellite / satellite beam / cell changes. To this end, it is necessary to organize orbit information by satellite beam / cell. Each satellite beam can be associated with an identifier to identify that specific beam. For example, a satellite beam can be associated with an SSB index. Alternatively, a satellite beam can be associated with a CSI-RS index.

[0178] A base station may be provided with information on satellite beams based on time that cover the current location of a specific terminal (or the geographical area / region / zone where the terminal is currently located). To this end, satellite-specific orbit information, such as that shown in FIG. 15 or FIG. 16, must be utilized separately for each satellite beam / cell. Satellite beams / cells may be linked to an SSB index for each base station. Alternatively, satellite beams / cells may be linked to a CSI-RS index for each base station. A gNB ID may be used for base station identification. For example, a specific satellite beam / cell may be identified through a combination of a base station identifier and an SSB-index.

[0179] A base station may have satellite beam / cell orbit information transmitted by the base station pre-configured and stored. Alternatively, such information may be pre-configured and stored through another network entity, node, application server, or OAM, and the base station may receive it by querying it. For example, a base station may receive satellite beam / cell orbit information transmitted by that base station from another or neighboring base station. As another example, a terminal may receive satellite beam / cell orbit information transmitted by the base station through any core network entity (e.g., AMF).

[0180] A base station may have time-based satellite beam / cell information pre-configured and stored for each location / geographic area / region / zone serviced by any satellite beam transmitted by the base station. Alternatively, such information may be pre-configured and stored through another network entity / node / application server or OAM, and a terminal or base station may receive it by querying it.

[0181] Orbit information for all satellites, satellite beams, and cells to service the terminal can be pre-stored, provisioned, or configured within the terminal (e.g., USIM). Orbit information for each satellite can be distinguished by assigning an ID or index to identify it. The base station can broadcast the corresponding satellite ID / identifier information through system information. Through this, the terminal can extract detailed orbit information of the corresponding satellite from the orbit information stored within the terminal (e.g., USIM), and accordingly derive location information (e.g., coordinate information) of the serving satellite. Alternatively, the terminal may derive the location information of the base station from any orbit information indicated by the base station through system information. The orbit information indicated by the base station through system information may be any information in FIG. 15 or FIG. 16, or information processed therefrom into any form.

[0182] A base station can request and receive current location information from a terminal and estimate the terminal's location based on the information received. The base station can request and receive assistance information from the terminal to estimate the terminal's location. For example, it can obtain information from the terminal that is helpful for estimating the terminal's location, such as the terminal's speed, direction of movement, movement path, destination, and time of arrival at the destination. Aircraft terminals, such as aircraft, may have movement path information by time period according to their flight schedule. The base station can specify the format of the information required to estimate the terminal's location and request it from the terminal. For example, it can request information on the time of arrival to the edge / boundary / center included within the coverage of neighboring satellites / satellite beams. As another example, it can request information on the direction of movement and the terminal's speed.

[0183] If the terminal has the capability to calculate / determine its location (e.g., using GNSS), the terminal can report its location information to the base station upon the request / instruction of the base station. If the terminal cannot calculate / determine its location, the area where the terminal is located can be distinguished by the terminal's current beam ID, cell ID, TAC, etc. The network can know the current satellite beam, cell, and TA of the connected terminal. The base station can determine the next candidate satellite beam / cell for a specific terminal using the received information and the satellite's orbit information. Alternatively, the base station can know the next candidate satellite beam / cell information for a specific terminal at its current location by considering the satellite beam change cycle / interval, etc., in any location / geographic area / region / zone. For example, if the satellite beam change cycle / interval is 5 minutes and the current location is estimated to be 2 minutes after the beam change, it can be estimated that the terminal will be serviced by Satellite Beam #2 after 3 minutes, by Satellite Beam #3 after 8 minutes, and by Satellite Beam #4 after 13 minutes.

[0184] FIG. 17 is a diagram illustrating, in an exemplary manner, the expected time for changing a satellite beam / cell based on satellite orbit information according to the present embodiment.

[0185] Referring to FIG. 17, the small circles (1610, 1620, 1630) marked with dashed lines in each satellite / satellite beam / cell represent the center portion of the corresponding satellite beam / cell coverage (1615, 1625, 1635) marked with solid lines. When the terminal is in the center portion (1610, 1620, 1630), the terminal may not perform a satellite / satellite beam / cell change within a short period of time. Therefore, it may be desirable to skip the cell measurement. On the other hand, when the terminal moves out of the center portion of each satellite beam / cell coverage, for example, when it moves out of the small circles (1610, 1620, 1630) marked with dashed lines, the terminal can be configured to perform a measurement.

[0186] This example can be applied to the Earth moving beam footprint scenario. Additionally, this example can be applied to the Earth fixed beam scenario. Since the satellite / satellite beam changes over time at specific locations / location areas / zones in both scenarios, the present invention can be applied regardless of the scenario. For example, in FIG. 17, if the terminal establishes / sets up an RRC connection via Satellite Beam #1 at t=0 and transitions to a connected state, the terminal does not need to perform measurements until t=2 because no change in the satellite / satellite beam / cell is expected. During the time from t=2 to t=4, a change in the satellite / satellite beam / cell is expected, so the terminal may need to perform measurement operations. That is, through duration information for the satellite beam / cell change, the terminal can be configured to perform cell measurements or cell measurement reports for the satellite beam / cell change only in a specific time area or at a specific location.

[0187] 2) Parameter configuration for skipping cell measurement and example of terminal operation according to the same

[0188] A base station may transmit configuration information to a terminal to instruct the terminal to perform a cell measurement skip operation when the terminal is located near the center of a serving satellite beam / cell coverage / footprint. For example, the base station may transmit configuration information to the terminal defining that the terminal is not required to perform a cell measurement near the center of a satellite beam / cell coverage / footprint. For another example, the base station may transmit configuration information to the terminal defining that the terminal is not required to perform a cell measurement during a time when a satellite beam / cell change is not expected.

[0189] For example, a base station may configure a skip duration, validity period, or time range in the terminal to skip cell measurements (when performing a measurement is not required). When the terminal receives an RRC message containing such parameters, it starts a timer set to the value of such parameters. For example, the terminal starts a timer with the parameter value set to the expiration value.

[0190] If the aforementioned configuration information is not configured in the terminal, the terminal performs a cell measurement operation. For example, the terminal performs a corresponding measurement operation on an associated neighbor cell on a specified frequency within the measurement target. Alternatively, the terminal derives a cell measurement result based on SSB using parameters specified by the base station for each trigger quantity and each measurement quantity from the measurement target. Alternatively, the terminal derives a cell measurement result based on CSI-RS using parameters specified by the base station for each trigger quantity and each measurement quantity from the measurement target. Alternatively, the terminal performs a measurement operation on a serving cell and / or a neighbor cell.

[0191] If configuration information is configured on the terminal and the timer set to the corresponding parameter value has not expired, the terminal skips the cell measurement operation.

[0192] If configuration information is configured in the terminal and the timer set with the corresponding parameter value expires, the terminal performs a cell measurement operation. For example, the terminal performs the corresponding measurement operation in an associated neighbor cell on the specified frequency within the measurement target. Alternatively, the terminal derives a cell measurement result based on SSB using parameters specified by the base station for each trigger quantity and each measurement quantity from the measurement target. Alternatively, the terminal derives a cell measurement result based on CSI-RS using parameters specified by the base station for each trigger quantity and each measurement quantity from the measurement target. Alternatively, the terminal performs a measurement operation for a serving cell and / or a neighbor cell.

[0193] As another example, the base station may configure the range of locations / location areas / zones in the terminal to skip cell measurements (where performing measurements is not required). Alternatively, the base station may configure the range of locations / location areas / zones and durations / valid times / time ranges in the terminal to skip cell measurements (where performing measurements is not required).

[0194] When the terminal receives an RRC message containing the relevant parameters, it sets the location information to the received values ​​to operate it, and / or starts a timer set to the received duration / valid time / time range parameter values. Here, the location information may refer to the geocentric fixed coordinate system x, y, z or their ranges, or latitude, longitude, elevation, or their ranges on Earth. Alternatively, the location information may refer to arbitrary location information, such as a zone identifier, when an arbitrary geographical area is divided into zones. Alternatively, the location information may refer to the identifier of the reference location area when an arbitrary geographical area is divided into reference location areas.

[0195] If configuration information is not configured in the terminal, the terminal performs a cell measurement operation. For example, the terminal performs a corresponding measurement operation on an associated neighbor cell on a specified frequency within the measurement target. Alternatively, the terminal derives a cell measurement result based on SSB using parameters specified by the base station for each trigger quantity and each measurement quantity from the measurement target. Alternatively, the terminal derives a cell measurement result based on CSI-RS using parameters specified by the base station for each trigger quantity and each measurement quantity from the measurement target. Alternatively, the terminal performs a measurement operation on a serving cell and / or neighbor cell.

[0196] If configuration information is configured on the terminal, the terminal does not go outside the range of the location / location area / zone, and the timer set to the corresponding parameter value has not expired, the terminal skips the cell measurement operation.

[0197] If configuration information is configured in the terminal, and the terminal moves out of the range of a location / location area / zone, or if the timer set to the corresponding parameter value expires, the terminal performs a cell measurement operation. For example, the terminal performs the corresponding measurement operation in an associated neighbor cell on the specified frequency within the measurement target. Alternatively, the terminal derives a cell measurement result based on SSB using parameters specified by the base station for each trigger quantity and each measurement quantity from the measurement target. Alternatively, the terminal derives a cell measurement result based on CSI-RS using parameters specified by the base station for each trigger quantity and each measurement quantity from the measurement target. Alternatively, the terminal performs a measurement operation for a serving cell and / or a neighbor cell.

[0198] The duration, validity period, and time range used in the aforementioned timer may be specified using values ​​based on Coordinated Universal Time (e.g., Coordinated Universal Time). The terminal may apply the values ​​specified based on Coordinated Universal Time as conditions. For example, the base station may specify the Coordinated Universal Time corresponding to the SFN boundary after the PDSCH end boundary where the RRC message is transmitted, and specify the offset time from this point until the cell measurement skip is terminated. As another example, the base station may specify the Coordinated Universal Time for the start of the next cell measurement. The terminal may already know the Coordinated Universal Time through system information (e.g., SIB9). Therefore, the terminal may utilize this information. As yet another example, the base station may specify the elapsed time (or offset time) until the start of the next cell measurement.

[0199] The aforementioned location / location area / zone / reference switch area may be pre-stored / provisioned / configured in a base station or terminal in the same manner as the aforementioned satellite orbit information. Alternatively, the location / location area / zone / reference switch area may be configured in the terminal by the base station. Information regarding the location / location area / zone / reference switch area configured by the base station may be used to calculate which location / location area / zone / reference switch area the terminal is included in based on the terminal's location information. A calculation formula for this purpose may be pre-configured in the terminal or instructed by the network. Accordingly, if the terminal has the capability to calculate / determine a location (e.g., using GNSS), the terminal can calculate which location / location area / zone / reference switch area it is included in at that location.

[0200] As another example, the base station may instruct the terminal on conditions to disable cell measurement skip (or to enter a section where cell measurement or cell measurement reporting is required).

[0201] For example, a base station can configure a measurement threshold (e.g., RSRP) for the relevant satellite beam in the terminal. The threshold information can be indicated in conjunction with a measurement ID included in the measurement configuration information. For instance, the condition information for the measurement threshold can be configured through a combination of one or more of Event A2 (Serving becomes worse than absolute threshold), which indicates that the quality of the source cell is worse than the absolute threshold; Event A4 (Neighbour becomes better than absolute threshold), which indicates that the quality of the target cell is better than the absolute threshold; and Event A3 (Neighbour becomes amount of offset better than PCell / PSCell), which is for general handover. Accordingly, the threshold information can be included within the Reporting Configuration (ReportConfigNR) information element.

[0202] As another example, the base station can configure a position TA (Timing Advance) threshold for the corresponding satellite beam in the terminal. TA is used to adjust the timing of uplink frames relative to downlink frames. TA is twice the propagation delay. TA has the smallest value when the terminal is at the center of the satellite beam, and the largest value when the terminal is at the edge of the satellite beam.

[0203] The terminal can obtain the TA using the following methods. First, the terminal can receive an initial TA value from the base station during a random access procedure. Alternatively, the base station can transmit the TA to the RRC connected terminal via MAC CE. Based on the TA received from the base station, the terminal can refine the TA by utilizing the terminal's location and the satellite's orbit information. For example, if the terminal knows its location, it can calculate the distance between the terminal and the satellite from the terminal's location and the satellite's location. The propagation delay can be obtained by dividing the distance value by the speed of light. Based on the TA value calculated using the satellite orbit information and the terminal's location information, and the TA threshold value indicated by the base station, the terminal can determine whether it has entered a section requiring cell measurement.

[0204] The aforementioned conditions may be used independently or in combination with any of the conditions. For example, when the aforementioned timer expires (or is in an expired state), cell measurement or cell measurement reporting may be initiated when the aforementioned measurement threshold is satisfied.

[0205] The base station may include cell change or beam change cycle information included in FIG. 17 as information for controlling / triggering measurement or reporting.

[0206] 3) An example of performing correction considering terminal movement, etc.

[0207] In scenarios where the satellite / satellite beam / cell moves, the location of the terminal may change when the satellite / satellite beam / cell moves. Even in scenarios where the satellite beam's footprint is fixed on Earth, the location of the terminal may change. In this case, it is necessary to adjust the time to skip cell measurements.

[0208] For example, the base station may instruct the terminal to provide a static offset parameter to compensate for the terminal's mobility, in addition to the duration / valid time / time range for skipping cell measurements (when performing measurements is not required). Once the said offset parameter is configured, the terminal may activate a set timer using a value obtained by adding or subtracting the said value from the duration / valid time / time range for skipping cell measurements.

[0209] As another example, the base station may instruct the terminal to provide a scaling parameter to compensate for the terminal's mobility, in addition to the duration / valid time / time range for skipping cell measurements (when performing a measurement is not required). Once the scaling parameter is configured, the terminal may activate a timer using the value obtained by multiplying the value by the duration / valid time / time range for skipping cell measurements.

[0210] As another example, the base station may instruct the terminal to include satellite beam information in the mobility history report to calculate the aforementioned offset parameter or scaling parameter. The mobility history report may include one or more pieces of information among a base station identifier, an SSB index or a CSI-RS index, and a timestamp. The terminal may report satellite beam-level mobility information (e.g., the mobility history report) to the base station. Transmission of satellite beam-level mobility information may be performed at the request of the base station in the case of establishing an RRC connection for an RRC idle terminal or resuming an RRC connection for an RRC inactive terminal. Alternatively, transmission of satellite beam-level mobility information may be performed at the request of the base station in the case of an RRC connected terminal. Or, when information indicating that mobility history information is available is included during the process of establishing or resuming an RRC connection, the terminal may transmit mobility history information at the request of the base station.

[0211] As another example, when a terminal performs a handover due to a change in satellite beam / cell, it can perform measurement operations according to configuration information instructed by the target base station associated with the target satellite beam / cell. Typically, RRC connection reconfiguration messages are configured to indicate only the changed parts. Therefore, if a handover is performed while the terminal is configured with configuration information including parameters to skip the aforementioned cell measurement by the source base station, those parameters are maintained. Consequently, even after the handover is completed, those parameters remain applied, allowing the terminal to skip the cell measurement.

[0212] As an example of preventing this, when a handover is performed (when a "Reconfiguration with sync" message is received), the terminal may disable the corresponding parameter. As another example, when a handover is performed (when a "Reconfiguration with sync" message is received), the terminal may stop the timer set by the corresponding parameter. As yet another example, when a handover is performed (when a "Reconfiguration with sync" message is received), the terminal may disable the timer set by the corresponding parameter. As yet another example, when a handover is performed (when a "Reconfiguration with sync" message is received), the terminal may start another timer to start the timer set by the corresponding parameter. And this other timer may be instructed by the base station.

[0213] As another example, it may be desirable to allow cell measurements to be performed in special cases, even if the terminal is located near the center of the satellite beam / cell coverage / footprint. For example, cell measurements should be allowed when a failure occurring at the L1 level, such as a RACH failure or RLC failure, is detected, even if the terminal is located near the center of the satellite beam / cell coverage / footprint. To this end, the terminal may perform or resume cell measurements and cell measurement reporting in specific cases (e.g., when a failure occurring at the L1 level, such as a RACH failure or RLC failure), even if parameters for skipping cell measurements are configured.

[0214] As another example, even if the terminal is located near the center of the satellite beam / cell coverage / footprint, it is necessary to perform a measurement in special cases (e.g., when the measured value is lower than a threshold). To explain the terminal operation considering such special cases, when the terminal receives an RRC message containing the relevant parameter, it starts a timer set to the parameter value to execute the operation.

[0215] If the terminal is not configured with configuration information for skipping cell measurement, the terminal performs the cell measurement operation.

[0216] If configuration information for skipping cell measurement is configured in the terminal, and the timer set to the corresponding parameter value has not expired, and the RSRP of the NR special cell is lower than the threshold value according to the S-measure configuration information, the terminal skips the measurement. That is, the S-measure configuration can be considered in priority over the aforementioned parameter. Conversely, it can also be implemented so that the aforementioned parameter is considered in priority over the S-measure configuration.

[0217] If configuration information for skipping cell measurement is configured in the terminal and the timer set to the corresponding parameter value has not expired, the terminal skips the cell measurement operation.

[0218] If configuration information for skipping cell measurement is configured in the terminal, and the timer set to the corresponding parameter value expires, the terminal performs the cell measurement operation.

[0219] As another example, even when the terminal is instructed to skip cell measurements because a satellite beam / cell is near the center of the corresponding coverage / footprint, the terminal may need to perform a cell measurement reporting operation. For instance, the terminal may not perform the corresponding cell measurements in accordance with configuration information that instructs the terminal to skip cell measurements because a satellite beam / cell is near the center of the corresponding coverage / footprint. However, even while not performing cell measurements, if a specific trigger type is configured in the cell measurement reporting configuration of the terminal (e.g., if the trigger type is configured as event or periodic), the terminal may transmit periodic cell measurement reports.

[0220] As described above, the embodiments provide the effect of enabling efficient cell measurement and measurement reporting of terminals serviced through a non-terrestrial network.

[0221] Below, the configuration of a terminal and a base station capable of performing all or part of the embodiments described with reference to FIGS. 1 to 17 is briefly described again.

[0222] FIG. 18 is a drawing for explaining a terminal configuration according to one embodiment.

[0223] Referring to FIG. 18, the embodiments may include a terminal (1800) that performs communication using a non-terrestrial network (NTN), a receiving unit (1830) that receives configuration information from a base station for controlling cell measurement or cell measurement reporting in the non-terrestrial network, and a control unit (1810) that determines whether to perform cell measurement or cell measurement reporting using the configuration information and controls the cell measurement or cell measurement reporting operation according to the determination result.

[0224] For example, the configuration information may include at least one of skip duration information for suspending the performance of cell measurement or cell measurement reporting for a certain period, location range information, and terminal movement correction parameter information. As an example, the configuration information may include at least one of a measurement period, threshold value, measurement location, timer value, and neighbor cell information for the terminal to perform a measurement operation on a cell. As another example, the configuration information may include at least one of a measurement report trigger condition, measurement report period, timer value, threshold value, and measurement report location for the terminal to perform a measurement operation on a cell and report the measurement to the base station. In addition, the configuration information may include parameters used by the terminal (1800) to measure and report the channel status of one or more cells or beams.

[0225] Meanwhile, as previously mentioned, since frequent handovers may occur when using a non-terrestrial network, information for skipping cell measurements or cell measurement reports may be further included in the configuration information. For example, the configuration information may include skip duration information for the terminal to skip (stop) cell measurements or cell measurement reports for a certain period, a timer value, location range information used to skip location-based cell measurements or cell measurement reports, and terminal movement correction parameter information for correcting the location by considering the terminal's mobility.

[0226] Configuration information can be received included in RRC messages or system information.

[0227] Additionally, the control unit (1810) determines whether a timer included in the configuration information is in operation, and if the timer is in operation, determines that the cell measurement or cell measurement reporting operation is not performed. For example, the configuration information may include a specific timer or timer value. When the timer start operation is triggered, the control unit (1810) starts the timer, and if the timer is in operation, it may not perform the cell measurement or cell measurement reporting even if it is triggered. If the timer expires, the control unit (1810) monitors whether the cell measurement or cell measurement reporting is triggered, and if it is triggered, it may perform the cell measurement or cell measurement reporting operation.

[0228] As another example, the target for determining whether to perform cell measurement or cell measurement reporting may be at least one of the serving cell, intra-frequency band, inter-frequency band, and inter-wireless access technology neighbor cells. That is, the determination of whether to perform cell measurement or cell measurement reporting based on the aforementioned timer operation may be made for all of the serving cell, intra-frequency band, inter-frequency band, and inter-wireless access technology neighbor cells. Alternatively, a different timer may be applied to each cell or measurement target. Or, among each cell or measurement target, a specific target may be designated by the base station, and the determination of whether to perform cell measurement or cell measurement reporting may be made only for the designated cell or measurement target. In this case, the configuration information may further include information regarding the cell or measurement target designated by the base station. Of course, conversely, the target for determining whether to perform cell measurement or cell measurement reporting may be selected excluding the cell or measurement target designated by the base station.

[0229] As described above, positional factors rather than temporal factors may be applied when determining cell measurement or cell measurement reporting. For example, if the terminal (1800) is located in a specific area indicated by configuration information, the control unit (1810) may determine that the cell measurement or cell measurement reporting operation is not performed. Conversely, if the terminal (1800) is not located in a specific area indicated by configuration information, the control unit (1810) may determine that the cell measurement or cell measurement reporting operation is not performed.

[0230] Additionally, if the control unit (1810) determines that cell measurement or cell measurement reporting is skipped and not performed, it may not perform cell measurement or cell measurement reporting even if it is triggered. That is, if it is determined that cell measurement or cell measurement reporting is not performed according to the aforementioned timer or position even if a normal cell measurement or cell measurement reporting cycle is reached and cell measurement or cell measurement reporting is triggered, the control unit (1810) does not perform cell measurement or cell measurement reporting operations during that cycle.

[0231] In addition, the control unit (1810) controls the overall operation of the terminal (1800) for controlling cell measurement or cell measurement reporting operations in a non-ground network necessary to perform the above-described embodiment.

[0232] The transmitting unit (1820) and the receiving unit (1830) are used to transmit and receive signals, messages, and data to and from a base station that are necessary to perform the above-described embodiments.

[0233] FIG. 19 is a drawing for explaining a base station configuration according to one embodiment.

[0234] Referring to FIG. 19, a base station (1900) using a non-terrestrial network (NTN) may include a transmitter (1920) that transmits configuration information to a terminal to control cell measurement or cell measurement reporting in the non-terrestrial network, and a receiver (1930) that receives a cell measurement report based on the result of the terminal determining whether to perform cell measurement or cell measurement reporting using the configuration information.

[0235] For example, the configuration information may include at least one of skip duration information for suspending the performance of cell measurement or cell measurement reporting for a certain period, location range information, and terminal movement correction parameter information. As an example, the configuration information may include at least one of a measurement period, threshold value, measurement location, timer value, and neighbor cell information for the terminal to perform a measurement operation on a cell. As another example, the configuration information may include at least one of a measurement report trigger condition, measurement report period, timer value, threshold value, and measurement report location for the terminal to perform a measurement operation on a cell and report the measurement to the base station. In addition, the configuration information may include parameters used by the terminal to measure and report the channel status of one or more cells or beams.

[0236] Additionally, the configuration information may include skip duration information for the terminal to skip (stop) cell measurement or cell measurement reporting for a certain period, a timer value, location range information used to skip location-based cell measurement or cell measurement reporting, and terminal movement correction parameter information for correcting the location by considering the mobility of the terminal.

[0237] The transmitting unit (1920) can transmit configuration information through RRC messages or system information.

[0238] For example, the terminal determines whether a timer included in the configuration information is running, and if the timer is running, determines that a cell measurement or cell measurement report operation is not performed. For example, the configuration information may include a specific timer or timer value. When a timer start operation is triggered, the terminal starts the timer, and if the timer is running, it may not perform the cell measurement or cell measurement report even if it is triggered. If the timer expires, the terminal monitors whether the cell measurement or cell measurement report is triggered, and if it is triggered, it may perform the cell measurement or cell measurement report operation.

[0239] As another example, the target for determining whether to perform cell measurement or cell measurement reporting may be at least one of the serving cell, intra-frequency band, inter-frequency band, and inter-wireless access technology neighbor cells. That is, the determination of whether to perform cell measurement or cell measurement reporting according to the aforementioned timer operation may be made for all of the serving cell, intra-frequency band, inter-frequency band, and inter-wireless access technology neighbor cells. Alternatively, a different timer may be applied to each cell or measurement target. Alternatively, among each cell or measurement target, a specific target may be designated by the base station (1900), and the determination of whether to perform cell measurement or cell measurement reporting may be made only for the designated cell or measurement target. In this case, the configuration information may further include information regarding the cell or measurement target designated by the base station (1900). Of course, conversely, the target for determining whether to perform cell measurement or cell measurement reporting may be selected excluding the cell or measurement target designated by the base station (1900).

[0240] As mentioned above, positional factors rather than temporal factors may be applied when determining cell measurement or cell measurement reporting. For example, if the terminal is located in a specific area indicated by configuration information, it may be determined that the cell measurement or cell measurement reporting operation is not performed. Conversely, if the terminal is not located in a specific area indicated by configuration information, it may be determined that the cell measurement or cell measurement reporting operation is not performed.

[0241] The receiving unit (1930) receives the cell measurement report from the terminal when the cell measurement and cell measurement report of the terminal are triggered and the conditions for performing the cell measurement report of the terminal are satisfied. For example, if the terminal determines that the cell measurement or cell measurement report is skipped and not to be performed, it may not perform the cell measurement or cell measurement report even if it is triggered. That is, if the general cell measurement or cell measurement report cycle is reached and the cell measurement or cell measurement report is triggered, but it is determined that it is not to be performed according to the aforementioned timer or position, the cell measurement or cell measurement report operation is not performed during that cycle.

[0242] In addition, the control unit (1910) controls the overall operation of the base station (1900) to control cell measurement or cell measurement reporting operations in a non-ground network necessary to perform the above-described embodiment.

[0243] The transmitting unit (1920) and the receiving unit (1930) are used to transmit and receive signals, messages, or data necessary to perform the above-described embodiments with a terminal or another base station.

[0244] The aforementioned embodiments may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP, and 3GPP2. That is, steps, configurations, and parts in the embodiments that are not described to clearly reveal the technical concept may be supported by the aforementioned standard documents. Furthermore, all terms disclosed in this specification may be explained by the standard documents disclosed above.

[0245] The embodiments described above may be implemented through various means. For example, the embodiments may be implemented by hardware, firmware, software, or a combination thereof.

[0246] In the case of implementation by hardware, the method according to the embodiments may be implemented by one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), processors, controllers, microcontrollers, or microprocessors.

[0247] In the case of implementation by firmware or software, the method according to the embodiments may be implemented in the form of a device, procedure, or function that performs the functions or operations described above. Software code may be stored in a memory unit and executed by a processor. The memory unit may be located inside or outside the processor and may exchange data with the processor by various means already known.

[0248] Additionally, terms such as "system," "processor," "controller," "component," "module," "interface," "model," or "unit" described above may generally refer to computer-related entities, hardware, combinations of hardware and software, software, or running software. For example, the aforementioned components may be, but are not limited to, processes driven by a processor, processors, controllers, control processors, objects, execution threads, programs, and / or computers. For example, both the application running on the controller or processor and the controller or processor may be components. One or more components may reside within a process and / or execution thread, and the components may be located on a single device (e.g., a system, a computing device, etc.) or distributed across two or more devices.

[0249] The foregoing description is merely an illustrative explanation of the technical concept of the present disclosure, and those skilled in the art to which the present disclosure pertains may make various modifications and variations within the scope of the essential characteristics of the technical concept. Furthermore, since these embodiments are intended to explain, not limit, the scope of the technical concept is not limited by these embodiments. The scope of protection of the present disclosure shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present disclosure.

Claims

Claim 1 A method for a terminal to perform communication using a non-terrestrial network (NTN), comprising: receiving configuration information from a base station for controlling cell measurement in the non-terrestrial network; determining whether to perform the cell measurement using the configuration information; and controlling the cell measurement operation according to the determination result, wherein the configuration information includes location range information used to determine whether to perform the cell measurement, and the location range information is used to determine a location area to suspend the cell measurement for a certain period based on the location of the non-terrestrial network cell and the location of the terminal, and the step of determining whether to perform determines that the cell measurement operation is not performed when the terminal is located in the location area. Claim 2 A method according to claim 1, wherein the configuration information further includes skip duration information for suspending the performance of the cell measurement for a certain period. Claim 3 In claim 2, the skip duration information includes valid time or time range information for skipping cell measurements in the coverage of the non-terrestrial network cell, and the valid time or time range is indicated as a value based on Coordinated Universal Time (UTC). Claim 4 delete Claim 5 In claim 1, the step of determining whether to perform the above is a method of determining, based on information included in the configuration information, that the cell measurement operation is performed before the non-terrestrial network cell stops service in the coverage area. Claim 6 In claim 1, the step of determining whether to perform the above is a method of determining whether to perform the cell measurement operation for at least one of an intra-frequency band, an inter-frequency band, and an inter-wireless access technology neighbor cell. Claim 7 delete Claim 8 In claim 1, the step of determining whether to perform the above is a method of determining to perform the cell measurement operation when the terminal is located outside the location area. Claim 9 delete Claim 10 In claim 1, the configuration information is received by being included in an RRC message or system information. Claim 11 A method according to claim 10, wherein the system information includes satellite orbit (ephemeris) information separated by cell, and the satellite orbit information is provided to the base station by querying the base station. Claim 12 A method for a base station to perform communication using a non-terrestrial network (NTN), comprising: a step of transmitting configuration information to a terminal to control cell measurement in the non-terrestrial network; and a step of receiving a cell measurement report based on the result of the terminal determining whether to perform the cell measurement using the configuration information, wherein the configuration information includes location range information used to determine whether to perform the cell measurement, and the location range information is used to determine a location area to suspend the cell measurement for a certain period based on the location of the non-terrestrial network cell and the location of the terminal, and the terminal determines that the cell measurement operation is not performed when the terminal is located in the location area. Claim 13 In claim 12, the configuration information further includes skip duration information for suspending the performance of the cell measurement for a certain period. Claim 14 In claim 13, the skip duration information includes valid time or time range information for skipping cell measurements in the coverage of the non-terrestrial network cell, and the valid time or time range is indicated as a value based on Coordinated Universal Time (UTC). Claim 15 delete Claim 16 In claim 12, the configuration information is transmitted by being included in an RRC message or system information. Claim 17 In claim 16, the system information includes satellite orbit (ephemeris) information separated by cell, and the satellite orbit information is provided to the base station upon query of the base station. Claim 18 A terminal that performs communication using a non-terrestrial network (NTN), comprising: a receiving unit that receives configuration information from a base station for controlling cell measurement in the non-terrestrial network; and a control unit that determines whether to perform the cell measurement using the configuration information and controls the cell measurement operation according to the determination result, wherein the configuration information includes location range information used to determine whether to perform the cell measurement, and the location range information is used to determine a location area to suspend the cell measurement for a certain period based on the location of the non-terrestrial network cell and the location of the terminal, and the control unit determines that the cell measurement operation is not performed when the terminal is located in the location area. Claim 19 In claim 18, the configuration information further comprises skip duration information for suspending the performance of the cell measurement for a certain period. Claim 20 In claim 19, the skip duration information includes valid time or time range information for skipping cell measurements in the coverage of the non-terrestrial network cell, and the valid time or time range is indicated as a value based on Coordinated Universal Time (UTC). Claim 21 delete Claim 22 In claim 18, the control unit is a terminal that determines whether to perform the cell measurement operation for at least one of an intra-frequency band, an inter-frequency band, and an inter-wireless access technology neighbor cell. Claim 23 delete Claim 24 A terminal according to claim 18, wherein the configuration information is received by being included in an RRC message or system information, the system information includes satellite orbit (ephemeris) information separated by cell, and the satellite orbit information is provided to the base station upon query of the base station. Claim 25 A base station that performs communication using a non-terrestrial network (NTN), comprising: a transmitting unit that transmits configuration information to a terminal for controlling cell measurement in the non-terrestrial network; and a receiving unit that receives a cell measurement report based on the result of the terminal determining whether to perform the cell measurement using the configuration information, wherein the configuration information includes location range information used to determine whether to perform the cell measurement, and the location range information is used to determine a location area to suspend the cell measurement for a certain period based on the location of the non-terrestrial network cell and the location of the terminal, and the base station that determines that the cell measurement operation is not performed when the terminal is located in the location area. Claim 26 In claim 25, the above configuration information further includes skip duration information for suspending the performance of the cell measurement for a certain period. Claim 27 In claim 26, the skip duration information includes valid time or time range information for skipping cell measurements in the coverage of the non-terrestrial network cell, and the valid time or time range is indicated as a value based on Coordinated Universal Time (UTC). Claim 28 delete Claim 29 A base station according to claim 25, wherein the configuration information is transmitted by being included in an RRC message or system information, the system information includes satellite orbit (ephemeris) information distinguished by cell, and the satellite orbit information is provided to the base station upon query of the base station.

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