Method and apparatus for adjusting timing advance in satellite communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. Disclosed are a method by which a user equipment (UE) performs uplink transmission in a satellite communication system, and an apparatus. The method comprises the operations of: performing initial access on the basis of a first timing advance (TA) value; after the initial access, receiving, from a satellite or a base station, uplink scheduling information and TA adjustment information related to an update of the first TA value; determining a second TA value on the basis of the TA adjustment information; and performing uplink transmission on the basis of the second TA value and the uplink scheduling information.

Description

Method and device for adjusting timing advance in satellite communication systems

[0001] The present disclosure relates to a satellite communication system, and more particularly to a method and apparatus for adjusting timing advance.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

[0004] Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

[0005] In addition, standardization of wireless interface architecture / protocols is in progress for technologies such as intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) that simplifies random access procedures. Standardization is also in progress for system architecture / services such as 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal.

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] Meanwhile, as satellite launch costs dramatically decreased in the late 2010s and into the 2020s, the number of companies seeking to provide satellite-based communication services increased. Consequently, satellite networks emerged as a next-generation network system complementing existing terrestrial networks. While they may not offer the same user experience as terrestrial networks, their advantage lies in their ability to provide communication services in areas where terrestrial network construction is difficult or in disaster situations. As previously mentioned, the recent sharp decline in satellite launch costs has also secured economic viability. Furthermore, several companies and the 3GPP standards body are pursuing direct smartphone-satellite communication.

[0009] When a terminal attempts to connect to a base station via satellite, the long distances between the terminal and the satellite, and between the satellite and the terrestrial base station, hundreds, thousands, or even more, cause significant delays in radio transmission. This significant delay is significantly greater than when the terminal and base station communicate directly over a terrestrial network. Furthermore, this delay varies over time due to the satellite's constant movement. All terminals experience varying delays with respect to the satellite or base station.

[0010] In particular, when a terminal transmits and receives signals with a base station via satellite, compensation for time offset may be necessary due to the long distance between the terminal and the satellite. Accordingly, the present disclosure provides a method and device in which a base station indicates time offset information to a terminal, the terminal calculates and applies a portion of a timing advance, the terminal reports the timing advance information to the base station, and the terminal uses the indicated information to compensate for the time offset.

[0011] The present disclosure relates to a communication system, and more particularly, to a method and device for a terminal to compensate for a time offset that varies over time due to the long distance to the satellite and the movement of the satellite when transmitting and receiving signals with a base station via a satellite, by having the base station designate a time offset and the terminal compensate based on the time offset. Furthermore, the present disclosure provides a method and device for the terminal to calculate a portion of the time offset based on satellite and its own location and time information, apply the offset, and report the same to the base station.

[0012] Embodiments of the present disclosure provide a method and apparatus for performing uplink transmission in a satellite communication system.

[0013] Embodiments of the present disclosure provide a method and apparatus for adjusting timing advance in a satellite communication system.

[0014] A method for adjusting timing advance (TA) by a terminal (UE) in a satellite communication system according to one embodiment of the present disclosure may include: receiving first upper layer signaling information including reference position information and / or reference time information related to a satellite; performing an initial connection based on a first TA value determined by applying the reference position information and / or reference time information; receiving, after the initial connection, downlink control information (DCI) including a TA adjustment field and uplink scheduling information related to an update of the TA value; and performing uplink transmission according to the uplink scheduling information based on a second TA value determined by applying the TA adjustment field.

[0015] In a satellite communication system according to one embodiment of the present disclosure, a terminal (UE) for adjusting timing advance includes a transceiver and a processor for controlling the transceiver, wherein the processor is configured to perform the following operations: receiving first upper layer signaling information including reference position information and / or reference time information related to a satellite; performing an initial connection based on a first TA (timing advance) value determined by applying the reference position information and / or reference time information; receiving, after the initial connection, downlink control information (DCI) including a TA adjustment field and uplink scheduling information related to an update of the TA value; and performing uplink transmission according to the uplink scheduling information based on a second TA value determined by applying the TA adjustment field.

[0016] FIG. 1 is a diagram showing the basic structure of a time-frequency domain, which is a radio resource domain in which data or a control channel is transmitted in a downlink or uplink, in a communication system according to one embodiment of the present disclosure.

[0017] FIG. 2 is a diagram illustrating a synchronization signal (SS) and a physical broadcast channel (PBCH) of a communication system according to one embodiment of the present disclosure, mapped in the frequency and time domains.

[0018] FIG. 3 is a diagram illustrating symbols in which an SS / PBCH block can be transmitted according to a subcarrier spacing according to one embodiment of the present disclosure.

[0019] FIG. 4 is a diagram illustrating an example of a control region (control resource set, CORESET) in which a downlink control channel is transmitted in a 5G wireless communication system according to one embodiment of the present disclosure.

[0020] FIG. 5 is a diagram schematically illustrating an example of a message transmitted from a MAC layer to a physical layer in a downlink in a communication system according to various embodiments of the present disclosure.

[0021] FIG. 6 is a diagram schematically illustrating an example of a message transmitted from a MAC layer to a physical layer in an uplink in a communication system according to various embodiments of the present disclosure.

[0022] FIG. 7 is a diagram illustrating an example of a process in which one transport block is divided into multiple code blocks and a CRC is added according to one embodiment of the present disclosure.

[0023] FIG. 8 is a diagram illustrating a processing time of a terminal according to timing advance when the terminal receives a first signal and transmits a second signal corresponding thereto in a 5G or NR system according to an embodiment of the present disclosure.

[0024] FIG. 9 is a diagram illustrating an example of scheduling and transmitting data (e.g., TB) according to slots according to one embodiment of the present disclosure, receiving HARQ-ACK feedback for the data, and performing retransmission according to the feedback.

[0025] FIG. 10 is a diagram illustrating an example of a communication system using a satellite according to one embodiment of the present disclosure.

[0026] FIG. 11 is a diagram illustrating the Earth orbital period of a communication satellite according to the altitude or height of the satellite according to one embodiment of the present disclosure.

[0027] FIG. 12 is a diagram illustrating a concept of satellite-terminal direct communication according to one embodiment of the present disclosure.

[0028] FIG. 13 is a diagram illustrating a utilization scenario of satellite-terminal direct communication according to one embodiment of the present disclosure.

[0029] FIG. 14 is a diagram illustrating an example of calculating an expected data transmission rate (throughput) in an uplink when a LEO satellite at an altitude of 1200 km and a terminal on the ground perform direct communication according to one embodiment of the present disclosure.

[0030] FIG. 15 is a diagram illustrating an example of calculating an expected data transmission rate (throughput) in an uplink when a GEO satellite at an altitude of 35,786 km and a terminal on the ground perform direct communication according to one embodiment of the present disclosure.

[0031] FIG. 16 is a diagram illustrating a path loss value according to a path loss model between a terminal and a satellite according to one embodiment of the present disclosure, and a path loss according to a path loss model between a terminal and a terrestrial network communication base station.

[0032] FIG. 17 is a diagram illustrating a formula and result for calculating the amount of Doppler shift experienced by a signal transmitted from a satellite when received by a ground user according to the altitude and position of the satellite and the position of a terminal user on the ground according to one embodiment of the present disclosure.

[0033] FIG. 18 is a diagram illustrating the velocity of a satellite calculated at the altitude of the satellite according to one embodiment of the present disclosure.

[0034] FIG. 19 is a diagram illustrating the Doppler shift experienced by different terminals within a single beam transmitted to the ground by a satellite according to one embodiment of the present disclosure.

[0035] FIG. 20 is a diagram illustrating the difference in Doppler shift occurring within one beam depending on the position of a satellite determined from an elevation angle according to one embodiment of the present disclosure.

[0036] FIG. 21 is a diagram illustrating the delay time from a terminal to a satellite and the round-trip delay time between a terminal, a satellite, and a base station according to the position of the satellite determined by the altitude angle according to one embodiment of the present disclosure.

[0037] FIG. 22 is a diagram illustrating a maximum difference value of round-trip delay time that varies depending on the user's position within one beam according to one embodiment of the present disclosure.

[0038] FIG. 23 is a diagram illustrating an example of an information structure of RAR according to one embodiment of the present disclosure.

[0039] FIG. 24 is a diagram illustrating an example of a relationship between a PRACH preamble setting resource and an RAR reception time of an LTE system according to one embodiment of the present disclosure.

[0040] FIG. 25 is a diagram illustrating an example of a relationship between a PRACH preamble setting resource and an RAR reception time of a 5G NR system according to one embodiment of the present disclosure.

[0041] FIG. 26 is a diagram showing the timing difference between downlink and uplink according to one embodiment of the present disclosure.

[0042] FIG. 27 is a drawing for explaining the movement of a satellite according to one embodiment of the present disclosure.

[0043] FIG. 28 is a drawing illustrating an example of the structure of an artificial satellite according to one embodiment of the present disclosure.

[0044] FIG. 29 is a diagram illustrating a terminal in an initial connection according to an embodiment of the present disclosure.TA This is a diagram showing an example of the process of determining .

[0045] FIG. 30 is a timing diagram illustrating a procedure for determining parameters for a TA according to one embodiment of the present disclosure.

[0046] FIG. 31 is a diagram schematically illustrating another example of an operation process of a terminal in a communication system according to one embodiment of the present disclosure.

[0047] FIG. 32 is a diagram schematically illustrating another example of an operation process of a terminal in a communication system according to one embodiment of the present disclosure.

[0048] FIG. 33 is a diagram illustrating an example of a base station operation for reporting a TA value of a terminal according to one embodiment of the present disclosure.

[0049] FIG. 34 is a diagram illustrating an example of terminal operation for reporting a TA value of a terminal according to one embodiment of the present disclosure.

[0050] FIG. 35 is a diagram illustrating an example of a difference in propagation delay time between a terrestrial network and a satellite network according to one embodiment of the present disclosure.

[0051] FIG. 36 is a diagram showing the change in distance between terminals belonging to the same coverage (or beam) within a satellite and a satellite according to one embodiment of the present disclosure.

[0052] FIG. 37 and FIG. 38 are conceptual diagrams showing a method for a terminal to transmit by applying TA according to one embodiment of the present disclosure.

[0053] FIG. 39 is a flowchart showing a method for a terminal without a GNSS function to adjust TA according to one embodiment of the present disclosure.

[0054] FIG. 40 is a diagram showing components necessary for calculating Doppler between a terminal and a satellite according to one embodiment of the present disclosure.

[0055] FIG. 41 is a diagram illustrating a series of processes in which a terminal according to one embodiment of the present disclosure receives each control information and transmits an uplink signal corresponding thereto.

[0056] FIG. 42 is a flowchart showing a procedure for adjusting TA depending on whether the network to which a terminal is connected is a satellite network or a terrestrial network according to one embodiment of the present disclosure.

[0057] FIG. 43 is a flowchart showing a procedure for adjusting TA according to a terminal capability report transmitted by a terminal according to one embodiment of the present disclosure.

[0058] FIG. 44 is a block diagram illustrating the internal structure of a terminal according to one embodiment of the present disclosure.

[0059] FIG. 45 is a block diagram illustrating the internal structure of a satellite according to one embodiment of the present disclosure.

[0060] FIG. 46 is a block diagram illustrating the internal structure of a base station according to one embodiment of the present disclosure.

[0061] NR (New Radio Access Technology), the new 5G communication technology, is designed to allow various services to be freely multiplexed across time and frequency resources. Accordingly, waveforms, numerology, and reference signals can be dynamically and freely allocated based on the needs of each service. In wireless communication, optimized data transmission through measurement of channel quality and interference is crucial for providing optimal services to terminals. Consequently, accurate channel status measurement is essential. However, unlike 4G communication, where channel and interference characteristics do not significantly vary depending on frequency resources, 5G channel and interference characteristics vary significantly depending on the service. Therefore, support for subsets at the Frequency Resource Group (FRG) level is required to enable separate measurement. Meanwhile, the types of services supported in NR systems can be categorized into categories such as eMBB (Enhanced mobile broadband), mMTC (massive Machine Type Communications) (mMTC), and URLLC (Ultra-Reliable and low-latency Communications). eMBB can be viewed as a service aimed at high-speed transmission of high-capacity data, mMTC aims at minimizing terminal power consumption and enabling multiple terminals to connect, and URLLC aims at high reliability and low latency. Different requirements may apply depending on the type of service applied to the terminal.

[0062] In this way, multiple services can be provided to users in a communication system, and in order to provide such multiple services to users, a method and a device using the same are required that can provide each service within the same time period according to its characteristics.

[0063] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0064] In describing the embodiments, descriptions of technical details that are well known in the technical field to which the embodiments of the present disclosure pertain and are not directly related to the embodiments of the present disclosure will be omitted. This is to more clearly convey the gist of the embodiments of the present disclosure without obscuring them by omitting unnecessary explanations.

[0065] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. The dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0066] Advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the embodiments of the present disclosure are not limited to the embodiments disclosed below and may be implemented in various different forms. This disclosure is provided solely to ensure that the disclosure of the embodiments is complete and to fully inform those skilled in the art of the scope of the invention, and the embodiments of the present disclosure are defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

[0067] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0068] Each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0069] Here, the term '~ unit' used in this embodiment means a software or hardware component such as an FPGA or ASIC, and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to regenerate one or more processors. Thus, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, the components and '~ units' may be implemented to regenerate one or more CPUs within a device or a secure multimedia card. Additionally, in the embodiment, '~bu' may include one or more processors.

[0070] Wireless communication systems are evolving from providing voice-centric services in the early days to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as 3GPP's HSPA (high speed Packet Access), LTE (long term evolution or E-UTRA (evolved universal terrestrial radio access)), LTE-Advanced (LTE-A), 3GPP2's HRPD (high rate packet data), UMB (ultra mobile broadband), and IEEE's 802.16e. 5G or NR (new radio) communication standards are being developed for the fifth generation of wireless communication systems.

[0071] As a representative example of the above broadband wireless communication system, the NR system adopts the orthogonal frequency division multiplexing (OFDM) method in the downlink (DL) and uplink. More specifically, the CP-OFDM (cyclic-prefix OFDM) method is adopted in the downlink, and both the CP-OFDM and the DFT-S-OFDM (discrete Fourier transform spreading OFDM) method are adopted in the uplink. The uplink refers to a wireless link in which a user equipment (UE) or mobile station (MS) transmits data or control signals to a base station (gNode B or base station (BS)), and the downlink refers to a wireless link in which a base station transmits data or control signals to a UE. The above multiple access method typically distinguishes the data or control information of each user by allocating and operating the time-frequency resources to be transmitted for each user so that they do not overlap, that is, so as to achieve orthogonality.

[0072] The NR system uses the hybrid automatic repeat request (HARQ) scheme, which retransmits the data at the physical layer if a decoding failure occurs in the initial transmission. In HARQ, if the receiver fails to correctly decode the data, the receiver transmits information (negative acknowledgment: NACK) to the transmitter to notify the receiver of the decoding failure, allowing the transmitter to retransmit the data at the physical layer. The receiver combines the retransmitted data with previously failed decoding data to improve data reception performance. If the receiver correctly decodes the data, it can transmit information (acknowledgement: ACK) to the transmitter to notify the transmitter of the decoding success, allowing the transmitter to transmit new data.

[0073] FIG. 1 is a diagram showing the basic structure of a time-frequency domain, which is a radio resource domain in which data or control channels are transmitted in downlink or uplink, in an NR system according to one embodiment of the present disclosure.

[0074] In Figure 1, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol, N symb (102) OFDM symbols are grouped to form one slot (106). The length of a subframe is defined as 1.0 ms, and a radio frame (114) is defined as 10 ms. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth is a total of N BW It consists of (104) subcarriers. 1 frame can be defined as 10ms. 1 subframe can be defined as 1ms, and therefore 1 frame can be composed of a total of 10 subframes. 1 slot can be defined as 14 OFDM symbols (i.e., the number of symbols per slot (Nsymb slot )=14). 1 subframe may consist of one or more slots, and the number of slots per subframe may vary depending on the setting value μ for the subcarrier spacing.

[0075] In an example of FIG. 2, cases where the subcarrier spacing setting value is μ=0 and μ=1 are illustrated. When μ=0, 1 subframe can be composed of 1 slot, and when μ=1, 1 subframe can be composed of 2 slots. In other words, the number of slots per subframe (N) depends on the setting value μ for the subcarrier spacing. slot subframe,μ) may vary, and accordingly the number of slots per frame (N slot frame,μ ) may vary. N according to each subcarrier spacing setting μ slot subframe, μ and N slot frame,μ can be defined as shown in Table 1 below.

[0076]

[0077] Before establishing an RRC (radio resource control) connection, a terminal can receive an initial bandwidth part (initial BWP) for initial access from a base station via a master information block (MIB). More specifically, during the initial access phase, the terminal can receive configuration information about a control resource set (CORESET) and a search space, through the MIB, where a physical downlink control channel (PDCCH) can be transmitted to receive system information required for initial access (remaining system information; may correspond to RMSI or system information block 1; SIB1).

[0078] The control region and search space set by MIB can each be regarded as identifier (ID) 0. The base station can notify the terminal of configuration information such as frequency allocation information, time allocation information, and numerology for control region #0 through MIB. In addition, the base station can notify the terminal of configuration information for monitoring cycle and occasion for control region #0, i.e. configuration information for search space #0, through MIB. The terminal can regard the frequency region set as control region #0 obtained from MIB as an initial bandwidth portion for initial access. At this time, the identifier (ID) of the initial bandwidth portion can be regarded as 0.

[0079] The MIB may contain information such as that shown in Table 2 below.

[0080]

[0081] The MIB fields are described as follows:

[0082] - cellBarred

[0083] Value barred means that the cell is barred, as defined in TS 38.304

[0020] .

[0084] - dmrs-TypeA-Position

[0085] Position of (first) DM-RS for downlink (see TS 38.211

[0016] , clause 7.4.1.1.2) and uplink (see TS 38.211

[0016] , clause 6.4.1.1.3).

[0086] - intraFreqReselection

[0087] Controls cell selection / reselection to intra-frequency cells when the highest ranked cell is barred, or treated as barred by the UE, as specified in TS 38.304

[0020] .

[0088] - pdcch-ConfigSIB1

[0089] Determines a common ControlResourceSet (CORESET), a common search space and necessary PDCCH parameters. If the field ssb-SubcarrierOffset indicates that SIB1 is absent, the field pdcch-ConfigSIB1 indicates the frequency positions where the UE may find SS / PBCH block with SIB1 or the frequency range where the network does not provide SS / PBCH block with SIB1 (see TS 38.213

[0013] , clause 13).

[0090] - ssb-SubcarrierOffset

[0091] Corresponds to kSSB (see TS 38.213

[0013] ), which is the frequency domain offset between SSB and the overall resource block grid in number of subcarriers. (See TS 38.211

[0016] , clause 7.4.3.1).

[0092] The value range of this field may be extended by an additional most significant bit encoded within PBCH as specified in TS 38.213

[0013] .

[0093] This field may indicate that this cell does not provide SIB1 and that there is hence no CORESET#0 configured in MIB (see TS 38.213

[0013] , clause 13). In this case, the field pdcch-ConfigSIB1 may indicate the frequency positions where the UE may (not) find a SS / PBCH with a control resource set and search space for SIB1 (see TS 38.213

[0013] , clause 13).

[0094] - subCarrierSpacingCommon

[0095] Subcarrier spacing for SIB1, Msg.2 / 4 for initial access, paging and broadcast SI-messages. If the UE acquires this MIB on an FR1 carrier frequency, the value scs15or60 corresponds to 15 kHz and the value scs30or120 corresponds to 30 kHz. If the UE acquires this MIB on an FR2 carrier frequency, the value scs15or60 corresponds to 60 kHz and the value scs30or120 corresponds to 120 kHz.

[0096] - systemFrameNumber

[0097] The 6 most significant bits (MSB) of the 10-bit System Frame Number (SFN). The 4 LSBs of the SFN are conveyed in the PBCH transport block as part of channel coding (ie outside the MIB encoding), as defined in clause 7.1 in TS 38.212

[0017] .

[0098] In the method of configuring the bandwidth portion, terminals prior to RRC connection can receive configuration information regarding the initial bandwidth portion through the MIB during the initial access phase. More specifically, the terminal can configure a control region for a downlink control channel through which downlink control information (DCI) for scheduling SIB can be transmitted from the MIB of the PBCH (physical broadcast channel). At this time, the bandwidth of the control region configured by the MIB can be regarded as the initial bandwidth portion, and the terminal can receive the PDSCH (physical downlink shared channel) through which the SIB is transmitted through the configured initial bandwidth portion. In addition to receiving the SIB, the initial bandwidth portion can also be utilized for other system information (OSI), paging, and random access.

[0099] When more than one bandwidth part is set for a terminal, the base station can instruct the terminal to change the bandwidth part using the bandwidth part indicator field in the DCI.

[0100] The basic unit of resources in the time-frequency domain is a resource element (RE), which can be represented by an OFDM symbol index and a subcarrier index. A resource block (RB or physical resource block; PRB) is a N-bit resource block in the frequency domain. RB It is defined as (110) consecutive subcarriers. In general, the minimum transmission unit of data is the RB unit. In NR systems, the N symb = 14, N RB =12, and N BW is proportional to the bandwidth of the system transmission band. The data rate can be increased in proportion to the number of RBs scheduled to the terminal.

[0101] In NR systems, downlink and uplink are operated by frequency division, and in the case of FDD systems, the downlink and uplink transmission bandwidths may differ. Channel bandwidth represents the RF bandwidth corresponding to the system transmission bandwidth.

[0102] [Table 3] and [Table 4] show some of the correspondences between system transmission bandwidth, subcarrier spacing, and channel bandwidth defined in NR systems in frequency bands lower than 6 GHz (frequency range 1 (FR 1)) and higher than 6 GHz (FR 2), respectively. For example, an NR system with a 100 MHz channel bandwidth and a 30 kHz subcarrier width has a transmission bandwidth composed of 273 RBs. In the following, N / A may be a bandwidth-subcarrier combination not supported by the NR system.

[0103]

[0104]

[0105] In the NR system, the frequency range can be divided into FR1 and FR2 and defined as shown in Table 5 below.

[0106]

[0107] The ranges of FR1 and FR2 above may be applied differently. For example, the frequency range of FR1 may be applied from 450 MHz to 6000 MHz.

[0108] Next, we will explain the SS (synchronization signal) / PBCH block in 5G.

[0109] An SS / PBCH block may refer to a physical layer channel block consisting of a PSS (primary SS), SSS (secondary SS), and PBCH. Specifically, it is as follows.

[0110] - PSS: A signal that serves as a reference for downlink time / frequency synchronization and provides some information about the cell ID.

[0111] - SSS: It serves as a reference for downlink time / frequency synchronization and provides remaining cell ID information not provided by PSS. Additionally, it can serve as a reference signal for PBCH demodulation.

[0112] - PBCH: Provides essential system information required for transmission and reception of data and control channels of a terminal. Essential system information may include at least one of search space-related control information indicating radio resource mapping information for the control channel, or scheduling control information for a separate data channel that transmits system information.

[0113] - SS / PBCH Block: An SS / PBCH block is composed of a combination of PSS, SSS, and PBCH. One or more SS / PBCH blocks can be transmitted within a 5ms period, and each transmitted SS / PBCH block can be distinguished by an index.

[0114] The terminal can detect PSS and SSS in the initial access stage, and decode PBCH. The terminal can obtain MIB from PBCH and set control region #0 (which may correspond to a control region with a control region index of 0) therefrom. The terminal can monitor control region #0, assuming that the selected SS / PBCH block and the DMRS (demodulation reference signal) transmitted in control region #0 are quasi-co-located (QCL). The terminal can receive system information through downlink control information transmitted in control region #0. The terminal can obtain RACH (random access channel)-related configuration information required for initial access from the received system information. The terminal can transmit a PRACH (physical RACH) to the base station considering the selected SS / PBCH index, and the base station receiving the PRACH can obtain information on the SS / PBCH block index selected by the terminal. Through this process, the base station can know which block among each SS / PBCH block the terminal has selected and monitor the control region #0 associated with it.

[0115] FIG. 2 is a diagram illustrating the mapping of a synchronization signal (SS) and a physical broadcast channel (PBCH) of a communication system in the frequency and time domains.

[0116] Referring to FIG. 2, a primary synchronization signal (PSS, 201), a secondary synchronization signal (SSS, 203), and a PBCH are mapped across 4 OFDM symbols, and the PSS and SSS are mapped to 12 RBs, and the PBCH is mapped to 20 RBs. The table in FIG. 2 shows how the frequency bands of the 20 RBs change according to the subcarrier spacing (SCS). The resource region where the PSS, SSS, and PBCH are transmitted may be referred to as an SS / PBCH block (SS / PBCH block). The SS / PBCH block may also be referred to as an SSB block.

[0117] FIG. 3 is a diagram illustrating symbols in which an SS / PBCH block can be transmitted according to a subcarrier spacing according to one embodiment of the present disclosure.

[0118] Referring to Fig. 3, the subcarrier spacing can be set to 15 kHz, 30 kHz, 120 kHz, 240 kHz, etc., and the position of the symbol where the SS / PBCH block (or SSB block) can be located can be determined according to each subcarrier spacing. Fig. 3 illustrates the position of the symbol where the SSB can be transmitted according to the subcarrier spacing in symbols within 1 ms, and the SSB does not always have to be transmitted in the area indicated in Fig. 3. The position where the SSB block is transmitted can be set to the terminal through system information or dedicated signaling.

[0119] Below, the downlink control channel in a 5G communication system will be described in more detail with reference to drawings.

[0120] FIG. 4 is a diagram illustrating an example of a control region (control resource set, CORESET) in which a downlink control channel is transmitted in a 5G wireless communication system according to one embodiment of the present disclosure.

[0121] Referring to FIG. 4, an example is illustrated in which two control regions (Control Region #1 (401), Control Region #2 (402)) are set within a UE bandwidth part (410) on the frequency axis and within one slot (420) on the time axis. The control regions (401, 402) can be set to specific frequency resources (403) within the entire UE bandwidth part (410) on the frequency axis. The time axis can be set to one or more OFDM symbols, which can be defined as the control region length (Control Resource Set Duration, 404). Referring to the illustrated example in FIG. 4, Control Region #1 (401) is set to a control region length of two symbols, and Control Region #2 (402) is set to a control region length of one symbol.

[0122] In the aforementioned 5G system, the control region can be established by the base station to the terminal via higher-layer signaling (e.g., system information, MIB, RRC signaling). Establishing a control region for the terminal means providing information such as the control region identifier (Identity), the frequency location of the control region, and the symbol length of the control region. For example, the higher-layer signaling may include the information in Table 6 below.

[0123]

[0124] In Table 6, the tci-StatesPDCCH (simply named TCI (transmission configuration indication) state) configuration information may include information on one or more SS / PBCH block indices or CSI-RS (channel state information reference signal) indices that are in a QCL relationship with the DMRS transmitted in the corresponding control region.

[0125] Next, we will specifically explain downlink control information (DCI) in 5G systems.

[0126] In a 5G system, scheduling information for uplink data (or physical uplink shared channel, PUSCH) or downlink data (or physical downlink shared channel, PDSCH) is transmitted from a base station to a terminal via DCI. The terminal can monitor a DCI format for fallback and a DCI format for non-fallback for the PUSCH or PDSCH. The fallback DCI format can be composed of fixed fields predefined between the base station and the terminal, and the non-fallback DCI format can include configurable fields. In addition, there are various formats for DCI, and each format can indicate whether it is DCI for power control or DCI for notifying a slot format indicator (SFI).

[0127] DCI can be transmitted through the physical downlink control channel (PDCCH) after going through the channel coding and modulation process. A cyclic redundancy check (CRC) is attached to the DCI message payload, and the CRC can be scrambled with a radio network temporary identifier (RNTI) corresponding to the identity of the UE. Different RNTIs can be used depending on the purpose of the DCI message, such as UE-specific data transmission, power control command, or random access response. That is, the RNTI is not transmitted explicitly, but is included in the CRC calculation process. When the UE receives a DCI message transmitted on the PDCCH, the UE verifies the CRC using the assigned RNTI. If the CRC verification result is correct, the UE can know that the message has been transmitted to the UE. The PDCCH is mapped and transmitted in a control resource set (CORESET) set for the UE.

[0128] For example, a DCI scheduling a PDSCH for system information (SI) may be scrambled with SI-RNTI. A DCI scheduling a PDSCH for a random access response (RAR) message may be scrambled with RA-RNTI. A DCI scheduling a PDSCH for a paging message may be scrambled with P-RNTI. A DCI notifying a slot format indicator (SFI) may be scrambled with SFI-RNTI. A DCI notifying a transmit power control (TPC) may be scrambled with TPC-RNTI. A DCI scheduling a UE-specific PDSCH or PUSCH may be scrambled with C-RNTI (Cell RNTI).

[0129] DCI format 0_0 can be used as a fallback DCI for scheduling PUSCH, in which case the CRC can be scrambled with C-RNTI. DCI format 0_0 with the CRC scrambled with C-RNTI can include, for example, the information in [Table 7] below.

[0130]

[0131] DCI format 0_1 ​​can be used as a fallback DCI for scheduling PUSCH, in which case the CRC can be scrambled with C-RNTI. DCI format 0_1 ​​with the CRC scrambled with C-RNTI can include, for example, the information in [Table 8] below.

[0132] - Carrier indicator - 0 or 3 bits- UL / SUL indicator - 0 or 1 bit- Identifier for DCI formats - [1] bits- Bandwidth part indicator - 0, 1 or 2 bits- Frequency domain resource assignment·For resource allocation type 0, ·For resource allocation type 1, - Time domain resource assignment -1, 2, 3, or 4 bits- VRB(virtual resource block)-to-PRB(physical resource block) mapping - 0 or 1 bit, only for resource allocation type 1.·0 bit if only resource allocation type 0 is configured;·1 bit otherwise.- Frequency hopping flag ― 0 or 1 bit, only for resource allocation type 1.·0 bit if only resource allocation type 0 is configured;·1 bit otherwise.- Modulation and coding scheme - 5 bits- New data indicator - 1 bit- Redundancy version - 2 bits- HARQ process number - 4 bits- 1st downlink assignment index - 1or 2 bits·1 bit for semi-static HARQ-ACK codebook;·2 bits for dynamic HARQ-ACK codebook with single HARQ-ACK codebook.- 2nd downlink assignment index - 0 or 2 bits·2 bits for dynamic HARQ-ACK codebook with two HARQ-ACK sub-codebooks;·0 bit otherwise.- TPC command for scheduled PUSCH - 2 bits- SRS resource indicator - bits· bits for non-codebook based PUSCH transmission· bits for codebook based PUSCH transmission- Precoding information and number of layers - up to 6 bits- Antenna ports - up to 5 bits- SRS request - 2 bits- CSI request - 0, 1, 2,3, 4, 5, or 6 bits- CBG (code block group) transmission information 0, 2, 4, 6, or 8 bits- PTRS-DMRS(phase tracking reference signal-demodulation) signal) association - 0 or 2 bits- beta-offset indicator - 0 or 2 bits- DMRS sequence initialization - 0 or 1bit

[0133] DCI format 1_0 can be used as a fallback DCI for scheduling PDSCH, in which case the CRC can be scrambled with C-RNTI. DCI format 1_0 with the CRC scrambled with C-RNTI can include, for example, the information in [Table 9] below.

[0134]

[0135] DCI format 1_1 can be used as a fallback DCI for scheduling PDSCH, in which case the CRC can be scrambled with C-RNTI. DCI format 1_1 with the CRC scrambled with C-RNTI can include, for example, the following information.

[0136]

[0137] For example, each control information included in DCI format 1_1, which is scheduling control information (DL grant) for downlink data, may be as follows.

[0138] - Carrier indicator: Indicates on which carrier the data scheduled by DCI is transmitted - 0 or 3 bits

[0139] - Identifier for DCI formats: This indicates the DCI format, and specifically, it is an indicator that distinguishes whether the DCI is for downlink or uplink. - [1] bits

[0140] - Bandwidth part indicator: Indicates if there is a change in the bandwidth part - 0, 1, or 2 bits

[0141] - Frequency domain resource assignment: Resource allocation information that indicates frequency domain resource allocation. The resource expressed varies depending on whether the resource allocation type is 0 or 1.

[0142] - Time domain resource assignment: Resource allocation information indicating time domain resource allocation, which can indicate the day setting of upper layer signaling or a predefined PDSCH time domain resource allocation list - 1, 2, 3, or 4 bits

[0143] - VRB-to-PRB mapping: Indicates the mapping relationship between virtual resource blocks (VRBs) and physical resource blocks (PRBs) - 0 or 1 bit

[0144] - PRB bundling size indicator: Indicates the physical resource block bundling size assuming the same precoding is applied - 0 or 1 bit

[0145] - Rate matching indicator: Indicates which rate match group among the rate match groups set by the upper layer applied to the PDSCH is applied - 0, 1, or 2 bits

[0146] - ZP CSI-RS trigger: Triggers the zero power channel state information reference signal - 0, 1, or 2 bits

[0147] - Transport block (TB) related configuration information: Indicates MCS (Modulation and coding scheme), NDI (New data indicator), and RV (Redundancy version) for one or two TBs.

[0148] - Modulation and coding scheme (MCS): Indicates the modulation method and coding rate used for data transmission. That is, it can indicate a coding rate value that can provide TBS and channel coding information, along with information such as whether it is QPSK, 16QAM, 64QAM, or 256QAM.

[0149] - New data indicator: Indicates whether this is a HARQ initial transmission or a retransmission.

[0150] - Redundancy version: Indicates the redundancy version of HARQ.

[0151] - HARQ process number: Indicates the HARQ process number applied to PDSCH - 4 bits

[0152] - Downlink assignment index: This is an index for generating a dynamic HARQ-ACK codebook when reporting HARQ-ACK for PDSCH - 0 or 2 or 4 bits

[0153] - TPC command for scheduled PUCCH: Power control information applied to PUCCH for HARQ-ACK reporting on PDSCH - 2 bits

[0154] - PUCCH resource indicator: Information indicating PUCCH resources for HARQ-ACK reporting on PDSCH - 3 bits

[0155] - PDSCH-to-HARQ_feedback timing indicator: Configuration information on which slot the PUCCH for HARQ-ACK reporting on the PDSCH is transmitted - 3 bits

[0156] - Antenna ports: Information indicating the antenna ports of the PDSCH DMRS and the DMRS CDM group where the PDSCH is not transmitted - 4, 5, or 6 bits

[0157] - Transmission configuration indication: Information indicating beam-related information of PDSCH - 0 or 3 bits

[0158] - SRS request: Information requesting SRS transmission - 2 bits

[0159] - CBG transmission information: When code block group-based retransmission is set, information indicating which code block group (CBG) data is transmitted through the PDSCH - 0, 2, 4, 6, or 8 bits

[0160] - CBG flushing out information: Information indicating whether the code block group previously received by the terminal can be used for HARQ combining - 0 or 1 bit

[0161] - DMRS sequence initialization: Indicates DMRS sequence initialization parameters - 1 bit

[0162] Below, a time domain resource allocation method for a data channel in a 5G communication system is described.

[0163] Downlink data can be transmitted on the PDSCH, a physical channel for downlink data transmission. Uplink data can be transmitted on the PUSCH, a physical channel for uplink data transmission. The PDSCH can be transmitted after the control channel transmission period, and scheduling information such as specific mapping locations and modulation methods in the frequency domain are determined based on the DCI transmitted via the PDCCH.

[0164] The base station can set up a table for time-domain resource allocation information for the downlink data channel (PDSCH) and the uplink data channel (PUSCH) to the terminal through higher-layer signaling (e.g., RRC signaling). For the PDSCH, a table consisting of up to maxNrofDL-Allocations=16 entries can be set up, and for the PUSCH, a table consisting of up to maxNrofUL-Allocations=16 entries can be set up. The time domain resource allocation information may include, for example, PDCCH-to-PDSCH slot timing (the time interval in slot units between the time point at which a PDCCH is received and the time point at which a PDSCH scheduled by the received PDCCH is transmitted, denoted as K0) or PDCCH-to-PUSCH slot timing (the time interval in slot units between the time point at which a PDCCH is received and the time point at which a PUSCH scheduled by the received PDCCH is transmitted, denoted as K2), information about the position and length of the start symbol for which a PDSCH or PUSCH is scheduled within a slot, the mapping type of the PDSCH or PUSCH, etc. For example, information such as those in Tables 11 and 12 below may be notified from the base station to the terminal.

[0165]

[0166]

[0167] The base station can notify the terminal of one of the entries in the table for the above time domain resource allocation information via L1 signaling (e.g., DCI) (e.g., by indicating it with the 'Time Domain Resource Allocation' field in the DCI). The terminal can obtain time domain resource allocation information for the PDSCH or PUSCH based on the DCI received from the base station.

[0168] In the above, the time domain resource assignment may be conveyed by information about a slot in which a PDSCH / PUSCH is transmitted, a starting symbol position S in the slot, and the number of symbols L to which the PDSCH / PUSCH is mapped. In the above, S may be a relative position from the start of the slot, L may be a number of consecutive symbols, and S and L may be determined from a start and length indicator value (SLIV) defined as in Equation 1 below.

[0169]

[0170] In the NR system, PDSCH mapping types are defined as type A and type B. In PDSCH mapping type A, the first DMRS symbol is located in the second or third OFDM symbol of a slot. In PDSCH mapping type B, the first DMRS symbol is located in the first OFDM symbol of the time-domain resource allocated for PUSCH transmission.

[0171] Among the control information constituting the DCI, the base station notifies the terminal of the modulation method applied to the PDSCH to be transmitted and the size of the data to be transmitted (transport block size, TBS) through MCS. In an embodiment, the MCS may be composed of 5 bits or more or fewer bits. The TBS corresponds to the size of the data (transport block, TB) to be transmitted by the base station before channel coding for error correction is applied.

[0172] In the present disclosure, a transport block (TB) may include a MAC (medium access control) header, a MAC control element, one or more MAC SDUs (service data units), and padding bits. Alternatively, a TB may refer to a unit of data delivered from a MAC layer to a physical layer or a MAC PDU (protocol data unit).

[0173] The modulation methods supported in the NR system are QPSK (quadrature phase shift keying), 16QAM (quadrature amplitude modulation), 64QAM, and 256QAM, and each modulation order (Q m ) correspond to 2, 4, 6, and 8. That is, 2 bits per symbol can be transmitted for QPSK modulation, 4 bits per symbol for 16QAM modulation, 6 bits per symbol for 64QAM modulation, and 8 bits per symbol for 256QAM modulation.

[0174] The terms "physical channel" and "signal" in NR systems may be used to describe the methods and devices proposed in the embodiments. However, the contents of the present disclosure may be applied to wireless communication systems other than NR systems.

[0175] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, when describing embodiments of the present disclosure, detailed descriptions of related functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the embodiments of the present disclosure. Furthermore, the terms described below are defined based on their functions in the present disclosure, and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the contents of the entire specification.

[0176] In the embodiments of the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station.

[0177] While the embodiments of the present disclosure are described below using the NR system as an example, the embodiments of the present disclosure may also be applied to other communication systems with similar technical backgrounds or channel types. The embodiments of the present disclosure may be applied to other communication systems with some modifications, as determined by a person skilled in the art, without significantly departing from the scope of the present disclosure.

[0178] In this disclosure, the terms "physical channel" and "signal" may be used interchangeably with data or control signals. For example, while PDSCH is a physical channel through which data is transmitted, in this disclosure, PDSCH may be used interchangeably with data.

[0179] In the present disclosure, higher layer signaling is a signal transmission method in which a signal is transmitted from a base station to a terminal using a downlink data channel of a physical layer, or from a terminal to a base station using an uplink data channel of a physical layer, and may also be referred to as RRC signaling or a MAC control element (MAC CE).

[0180] In various embodiments of the present disclosure, information about Timing Advance (TA) may be transmitted via at least one of a MAC Control Element (CE), for example, a Timing Advance Command MAC CE or an Absolute Timing Advance Command MAC CE.

[0181] A message from the MAC layer transmitted to the physical layer, e.g., a MAC PDU, may contain one or more MAC sub-PDUs. In one embodiment, each MAC sub-PDU may contain any of the following:

[0182] . MAC subheader only (including padding);

[0183] . MAC subheader and MAC SDU;

[0184] . MAC subheader and MAC CE; or

[0185] . MAC subheader and padding.

[0186] MAC SDUs have variable sizes, and each MAC subheader may correspond to a MAC SDU, a MAC CE, or padding.

[0187] Messages from the MAC layer transmitted to the physical layer, for example, MAC PDUs, can be configured as shown in FIGS. 5 and 6 for downlink and uplink, respectively.

[0188] FIG. 5 is a schematic diagram illustrating an example of a message transmitted from the MAC layer to the physical layer in a downlink in a communication system according to various embodiments of the present disclosure. An example of a message transmitted from the MAC layer to the physical layer in the downlink may be a downlink MAC PDU (DL MAC PDU).

[0189] Referring to FIG. 5, a MAC sub-PDU (500) including MAC CE 1 includes an R / LCID subheader (502) and a fixed-sized MAC CE (504), and a MAC sub-PDU (510) including MAC CE 2 includes an R / F / LCID / L subheader (512) and a variable-sized MAC CE (514). A MAC sub-PDU (520) including a MAC SDU includes an R / F / LCID / L subheader (522) and a MAC SDU (524).

[0190] LCID represents a logical channel ID field, and the LCID field indicates an instance of a corresponding MAC SDU or a type or padding of a corresponding MAC CE. [Table 13] below shows values ​​of LCID for DL-SCH according to one embodiment, and [Table 14] shows values ​​of LCID for UL-SCH according to one embodiment.

[0191]

[0192]

[0193] There is one LCID field per MAC subheader, and the size of the LCID field is 6 bits. When the LCID field is set to, for example, "34", there is one additional octet in the MAC subheader including the eLCID field, and it follows the octet including the LCID field. When the LCID field is set to, for example, "33", there are two additional octets in the MAC subheader including the eLCID field, and these two octets follow the octet including the LCID field.

[0194] eLCID represents the Extended Logical Channel ID field and indicates the logical channel instance of the corresponding MAC SDU or the type of the corresponding MAC CE. The size of the eLCID field is 8 or 16 bits.

[0195] L represents a length field, which indicates the length of the corresponding MAC SDU or variable-size MAC CE. There is one length field for each MAC subheader, excluding subheaders corresponding to fixed-size MAC CEs, padding, or MAC SDUs containing the UL common control channel (CCCH). The size of the length field is indicated by the F field.

[0196] F represents the format field and indicates the size of the length field. There is one F field for each MAC subheader, excluding MAC SDUs containing fixed MAC CEs, padding, and UL CCCH. The size of the F field is 1 bit. For example, a value of 0 indicates 8 bits of the length field, and for another example, a value of 1 indicates 16 bits of the length field.

[0197] R is a reserved bit, set to "0" for example.

[0198] As illustrated in FIG. 5, MAC CEs, for example, MAC CE 1 and MAC CE 2, are placed together, and MAC sub-PDU(s) containing MAC CE(s) are placed before MAC sub-PDU(s) containing MAC SDU(s) and MAC sub-PDU(s) containing padding. Here, the size of the padding can be zero.

[0199] FIG. 6 is a diagram schematically illustrating an example of a message transmitted from a MAC layer to a physical layer in an uplink in a communication system according to various embodiments of the present disclosure.

[0200] Referring to FIG. 6, an example of a message transmitted from the MAC layer to the physical layer in the uplink may be an uplink MAC PDU (UL MAC PDU). A MAC sub-PDU (610) including MAC CE 1 includes an R / LCID subheader (612) and a fixed-size MAC CE (614), and a MAC sub-PDU (620) including MAC CE 2 includes an R / F / LCID / L subheader (622) and a variable-size MAC CE (624). A MAC sub-PDU (600) including a MAC SDU includes an R / F / LCID / L subheader (602) and a MAC SDU (604).

[0201] MAC CEs, for example, MAC CE 1 and MAC CE 2, are placed together, and MAC sub-PDU(s) containing the MAC CE(s) are placed after the MAC sub-PDU containing the MAC SDU and before the MAC sub-PDU containing the padding. Here, the size of the padding can be zero.

[0202] In FIGS. 5 and 6, the LCID included in the subheader of the MAC layer, i.e., the logical channel ID or the extended logical channel ID (eLCID), can indicate the type of the transmitted MAC SDU or MAC CE. The mapping between the index of the LCID and the type of the MAC SDU or MAC CE can be represented, for example, as in Table 13, and the mapping between the index of the eLCID and the type of the MAC SDU or MAC CE can be represented, for example, as in Table 14. In various embodiments of the present disclosure, the LCID can indicate an instance of a logical channel of the MAC SDU, a type of the MAC CE, or padding information of a downlink shared channel (DL-SCH) and an uplink shared channel (UL-SCH). One LCID is mapped per MAC subheader, and the LCID can be implemented with, for example, 6 bits.

[0203] FIG. 7 is a diagram illustrating an example of a process in which one transport block is divided into multiple code blocks and a CRC is added according to one embodiment of the present disclosure.

[0204] Referring to FIG. 7, a CRC (703) may be added to the last or first part of a transport block (TB, 701) to be transmitted in uplink or downlink. The CRC (703) may have 16 bits or 25 bits, a fixed number of bits, or a variable number of bits depending on channel conditions, and may be used to determine whether channel coding is successful. A block to which the CRC (703) is added to the TB (701) may be divided into several code blocks (codeblocks, CB) (707, 709, 711, 713) (705). Here, the code blocks may be divided with a maximum size predetermined, and in this case, the last code block (713) may be smaller than the other code blocks (707, 709, 711). However, this is just an example, and according to another example, the lengths of the last code block (713) and other code blocks (707, 709, 711) can be made the same by inserting 0, a random value, or 1 into the last code block (713).

[0205] Additionally, CRCs (717, 719, 721, 723) may be added to each of the code blocks (707, 709, 711, 713) (715). The CRC may have 16 bits, 24 bits, or a predetermined number of bits, and may be used to determine whether channel coding is successful.

[0206] TB(701) and a cyclic generator polynomial can be used to generate CRC(703), and the cyclic generator polynomial can be defined in various ways. For example, the cyclic generator polynomial gCRC24A(D) = D for a 24-bit CRC. 24 + D 23 + D 18 + D 17 + D 14 + D 11 + D 10+ D 7 + D 6 + D 5 + D 4 + D 3 Assuming + D + 1 and L = 24, TB data a0,a1,a2,a3,...,a A-1 For CRC p0,p1,p2,p3,...,p L-1 Silver a0D A+23 +a1D A+22 +...a A-1 D 24 +p0D 23 +p1D 22 +...+p 22 D 1 +p 23 It can be determined as a value that divides gCRC24A(D) so that the remainder becomes 0. In the above example, the CRC length L was explained assuming 24 as an example, but the CRC length L can be determined to various lengths such as 12, 16, 24, 32, 40, 48, and 64.

[0207] After the CRC is added to the TB through this process, the TB+CRC can be divided into N CBs (707, 709, 711, 713). A CRC (717, 719, 721, 723) can be added to each of the divided CBs (707, 709, 711, 713) (715). The CRC added to the CB may have a different length than that used when generating the CRC added to the TB, or a different cyclic generator polynomial may be used for CRC generation. In addition, the CRC (703) added to the TB and the CRCs (717, 719, 721, 723) added to the code block may be omitted depending on the type of channel code to be applied to the code block. For example, if an LDPC code rather than a turbo code is applied to a code block, the CRCs (717, 719, 721, 723) to be inserted into each code block may be omitted.

[0208] However, even when LDPC is applied, CRCs (717, 719, 721, 723) can be added to the code block as is. Also, when polar codes are used, CRCs can be added or omitted.

[0209] As described above in FIG. 7, the maximum length of one code block is determined according to the type of channel coding applied to the TB to be transmitted, and the TB and the CRC added to the TB can be divided into code blocks according to the maximum length of the code block.

[0210] In the conventional LTE system, a CRC for CB is added to the divided CB, the data bits and CRC of the CB are encoded with a channel code, coded bits are determined, and the number of bits that are rate-matched is determined as promised in advance for each coded bit.

[0211] In the NR system, the size of TB (TBS) can be calculated through the following steps.

[0212] Step 1: N' is the number of REs allocated for PDSCH mapping in one PRB within the allocated resources. RB Calculate N' RB is N SC RB ·N symb sh - N DMRS PRB - N oh PRB can be calculated as . Here, N SC RB is 12, and N symb sh can represent the number of OFDM symbols allocated to the PDSCH. N DMRS PRB is the number of REs in a PRB occupied by DMRSs of the same CDM group. N oh PRBis the number of REs occupied by overhead within a PRB set by upper signaling, and can be set to one of 0, 6, 12, and 18. After this, the total number of REs allocated to the PDSCH, N RE can be calculated. N RE is min(156,N' RE )·n PRB is calculated as , n PRB Indicates the number of PRBs allocated to the terminal.

[0213] Step 2: Number of temporary information bits N Info is N RE * R * Q m * can be calculated as v. Here, R is the code rate, and Q m is the modulation order, and the information of this value can be transmitted using the MCS bit field of DCI and a pre-arranged table. v is the number of allocated layers. If N Info If it is 3824, TBS can be calculated through step 3 below. Otherwise, TBS can be calculated through step 4.

[0214] Step 3: and N' through the formula Info can be calculated. TBS is N' in Table 15 below. Info N' among values ​​not less than Info can be determined as the closest value.

[0215]

[0216] Step 4: and N' through the formula Info can be calculated. TBS is N' Info The value can be determined through [pseudo-code 1] below. Below, C corresponds to the number of code blocks contained in one TB.

[0217] [Pseudo-code 1 Start]

[0218]

[0219] [End of Pseudo-code 1]

[0220] In the NR system, when one CB is input to the LDPC encoder, parity bits can be added and output. At this time, the amount of parity bits can vary depending on the LDPC base graph. The method of sending all parity bits generated by LDPC coding for a specific input can be called FBRM (full buffer rate matching), and the method of limiting the number of transmittable parity bits can be called LBRM (limited buffer rate matching). When resources are allocated for data transmission, the LDPC encoder output is made into a circular buffer, and the bits of the created buffer are repeatedly transmitted as many times as the allocated resources, and the length of the circular buffer is N. cb It can be said that.

[0221] If the number of all parity bits generated by LDPC coding is N, then in the FBRM method, N cb = N. In the LBRM method, N cb is min(N,N ref ) and N ref Is is given as R LBRM can be decided by 2 / 3. TBS LBRM In order to obtain , the method for obtaining TBS described above is used, but the maximum number of layers and maximum modulation order supported by the terminal in the cell are assumed, and the maximum modulation order Q mis assumed to be 8 if the cell is set to use an MCS table that supports 256QAM for at least one BWP, otherwise it is assumed to be 6 (64QAM), the code rate is assumed to be the maximum code rate of 948 / 1024, and N RE is 156·n PRB is assumed to be n PRB is n PRB,LBRM It is calculated assuming n PRB,LBRM can be given as Table 16 below.

[0222]

[0223] The maximum data rate supported by a terminal in an NR system can be determined using the following mathematical expression 2.

[0224]

[0225] In the above mathematical expression 2, J is the number of carriers bound by carrier aggregation, Rmax = 948 / 1024, and v Layers (j) is the maximum number of layers, Q m (j) is the maximum modulation order, f (j) is the scaling factor, μ can mean the subcarrier spacing. f (j) The terminal can report one of the values ​​1, 0.8, 0.75, and 0.4, and μ can be given as [Table 17] below.

[0226]

[0227] T s μ is the average OFDM symbol length, and T s μ is 10 -3 / (14·2 μ ) can be calculated as N PRR BW(j),μ is the maximum number of RBs in BW(j). OH (j)is an overhead value, which can be given as 0.14 in downlink and 0.18 in uplink of FR1 (band below 6 GHz), and 0.08 in downlink and 0.10 in uplink of FR2 (band above 6 GHz). Through mathematical expression 2, the maximum data rate in downlink in a cell with a frequency bandwidth of 100 MHz at a subcarrier spacing of 30 kHz can be calculated as shown in [Table 18] below.

[0228]

[0229] On the other hand, the actual data rate that a terminal can measure in actual data transmission may be the data amount divided by the data transmission time. This may be the TBS for 1 TB transmission or the sum of TBS for 2 TB transmission divided by the TTI length. For example, assuming Table 15, the maximum actual data rate in downlink in a cell with a 100 MHz frequency bandwidth at a 30 kHz subcarrier spacing may be determined as shown in [Table 19] below depending on the number of allocated PDSCH symbols.

[0230]

[0231] Table 18 shows the maximum data rate supported by the terminal, and Table 16 shows the actual data rate based on the allocated TBS. Depending on scheduling information, the actual data rate may be higher than the maximum data rate.

[0232] In wireless communication systems, particularly New Radio (NR) systems, the data rate that a terminal can support can be mutually agreed upon between the base station and the terminal. This can be calculated using the maximum frequency band, maximum modulation order, and maximum number of layers supported by the terminal. However, the calculated data rate may differ from the value calculated from the transport block size (TBS) and transmission time interval (TTI) length used for actual data transmission.

[0233] Accordingly, a terminal may be allocated a TBS that is greater than the data rate it supports. To prevent this, there may be restrictions on the schedulable TBS depending on the data rate supported by the terminal.

[0234] Since terminals are typically located far from the base station, signals transmitted from the terminal are received at the base station after a propagation delay. Propagation delay is the distance a radio wave travels from the terminal to the base station divided by the speed of light, and is typically the distance from the terminal to the base station divided by the speed of light. In one embodiment, for a terminal located 100 km away from the base station, a signal transmitted from the terminal is received at the base station approximately 0.34 msec later. Conversely, a signal transmitted from the base station is also received at the terminal approximately 0.34 msec later. As described above, the time it takes for a signal transmitted from a terminal to arrive at the base station may vary depending on the distance between the terminal and the base station. Therefore, if multiple terminals located in different locations transmit signals simultaneously, the arrival times at the base station may all be different. To address this issue and ensure that signals transmitted from multiple terminals arrive at the base station simultaneously, the uplink signal can be transmitted at different times for each terminal depending on its location. In 5G, NR, and LTE systems, this is called timing advance.

[0235] FIG. 8 is a diagram illustrating a processing time of a terminal according to timing advance when the terminal receives a first signal and transmits a second signal corresponding thereto in a 5G or NR system according to an embodiment of the present disclosure.

[0236] Referring to FIG. 8, when the base station transmits the first signal (uplink scheduling grant (UL grant) or downlink control signal and data (DL grant and DL data)) to the terminal in slot n (802), the terminal can receive the first signal in slot n (804). At this time, the terminal may receive the first signal at a transmission delay time (T) longer than the time at which the base station transmitted the signal. p, 810) can receive a signal as late as possible. In the present embodiment, when the terminal receives the first signal in slot n (804), the terminal transmits the corresponding second signal (HARQ-ACK / NACK for uplink data or downlink data) in slot n+4 (806). Even when the terminal transmits a signal to the base station, in order to arrive at the base station at a specific time, the terminal can transmit the second signal at a timing (806) that is earlier than slot n+4 by a timing advance (TA, 812) based on the standard of the signal received by the terminal. Therefore, in the present embodiment, the time that the terminal can receive uplink scheduling approval and transmit uplink data or receive downlink data and prepare to transmit HARQ ACK or NACK may be the time corresponding to three slots minus the TA (814).

[0237] To determine the timing described above, the base station can calculate the absolute value of the TA of the corresponding terminal. The base station can calculate the absolute value of the TA by adding or subtracting the amount of change in the TA value transmitted through upper signaling thereafter to the TA value initially transmitted to the terminal during the random access phase when the terminal initially accesses. In the present disclosure, the absolute value of the TA can be a value obtained by subtracting the start time of the nth TTI received by the terminal from the start time of the nth TTI transmitted by the terminal.

[0238] Meanwhile, one of the key performance criteria of cellular wireless communication systems is packet data latency. To achieve this, LTE systems transmit and receive signals in subframe units with a 1ms transmission time interval (TTI). As described above, an LTE system can support short-TTI UEs (UEs) with a transmission time interval shorter than 1ms. Meanwhile, in 5G or NR systems, the transmission time interval can be shorter than 1ms. Short-TTI UEs are suitable for services where latency is critical, such as Voice over LTE (VoLTE) and remote control. Furthermore, short-TTI UEs can serve as a means to realize the mission-critical Internet of Things (IoT) on a cellular basis.

[0239] In a 5G or NR system, when a base station transmits a PDSCH including downlink data, the DCI that schedules the PDSCH indicates a K1 value corresponding to timing information for transmitting HARQ-ACK information of the PDSCH by the terminal. The HARQ-ACK information may be transmitted by the terminal to the base station unless it is instructed to be transmitted before symbol L1, including a timing advance. That is, the HARQ-ACK information may be transmitted from the terminal to the base station at a time equal to or later than symbol L1, including a timing advance. If the HARQ-ACK information is instructed to be transmitted before symbol L1, including a timing advance, the HARQ-ACK information may not be valid HARQ-ACK information in HARQ-ACK transmission from the terminal to the base station.

[0240] Symbol L1 is T from the last point of PDSCH. proc,1It may be the first symbol after which a cyclic prefix (CP) begins. T proc,1 can be calculated as shown in mathematical formula 3 below.

[0241]

[0242] In the above mathematical expression 3, N1, d 1,1 , d 1,2 , , μ, TC can be defined as follows.

[0243] - When HARQ-ACK information is transmitted on PUCCH (uplink control channel), d 1,1 =0, and if transmitted on PUSCH (uplink shared channel, data channel), d 1,1 =1.

[0244] - When a terminal is configured with multiple activated configuration carriers or carriers, the maximum timing difference between carriers may be reflected in the second signal transmission.

[0245] - For PDSCH mapping type A, i.e., when the first DMRS symbol position is the 3rd or 4th symbol of the slot, if the position index i of the last symbol of the PDSCH is less than 7, d 1,2 It is defined as =7-i.

[0246] - For PDSCH mapping type B, i.e., when the first DMRS symbol position is the first symbol of the PDSCH, if the length of the PDSCH is 4 symbols, d 1,2 =3, and if the length of PDSCH is 2 symbols, d 1,2 =3+d, where d is the number of symbols overlapping the PDSCH and the PDCCH including the control signal scheduling the PDSCH.

[0247] - N1 is defined according to μ as shown in Table 20 below. μ=0, 1, 2, 3 mean subcarrier spacing of 15 kHz, 30 kHz, 60 kHz, 120 kHz, respectively.

[0248]

[0249] The N1 value provided in Table 20 described above may have different values ​​defined as follows depending on the UE capability.

[0250]

[0251] In a 5G or NR system, when a base station transmits control information including uplink scheduling approval, the terminal may indicate a K2 value corresponding to timing information for transmitting uplink data or PUSCH.

[0252] A PUSCH may be transmitted from a UE to a base station unless it is instructed to be transmitted before symbol L2, including a timing advance. That is, a PUSCH may be transmitted from a UE to a base station at a time equal to or later than symbol L2, including a timing advance. If a PUSCH is instructed to be transmitted before symbol L2, including a timing advance, the UE may ignore uplink scheduling grant control information from the base station.

[0253] Symbol L2 is T from the last point of PDCCH containing scheduling grant. proc,2 The CP of the PUSCH symbol to be transmitted later may be the first symbol starting with T proc,2 can be calculated as shown in mathematical formula 4 below.

[0254]

[0255] In the above mathematical expression 4, N2, d 2,1 , , μ, T C can be defined as follows.

[0256] - If the first symbol among the PUSCH allocated symbols contains only DMRS, then d 2,1 =0, otherwise d 2,1 =1.

[0257] - If the terminal is configured with multiple activated configuration carriers or carriers, the maximum timing difference between carriers may be reflected in the second signal transmission.

[0258] - N2 is defined as shown in Table 21 below according to μ. μ=0, 1, 2, 3 mean subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, and 120 kHz, respectively.

[0259]

[0260] - The N2 value provided in Table 21 described above may be used as different values ​​defined as follows depending on the UE capability.

[0261]

[0262] Meanwhile, 5G or NR systems can configure frequency band portions (BWPs) within a single carrier, allowing specific terminals to transmit and receive within the configured BWP. This can be used to reduce terminal power consumption. Base stations can configure multiple BWPs and change the activated BWP in control information. The time available to a terminal while a BWP is being changed can be defined as shown in [Table 22] below.

[0263]

[0264] In [Table 22], the frequency range FR1 refers to a frequency band below 6 GHz, and the frequency range FR2 refers to a frequency band above 6 GHz, and they can be distinguished as shown in Table 4. Typically, FR2 refers to a high-frequency band close to the mmWave band, and FR1 refers to a relatively low-frequency band compared to FR2. In the above-described embodiment, Type 1 and Type 2 can be determined according to UE capability. In the above-described embodiment, Scenarios 1, 2, 3, and 4 are given as shown in Table 23 below.

[0265]

[0266] FIG. 9 is a diagram illustrating an example of scheduling and transmitting data (e.g., TB) according to slots, receiving HARQ-ACK feedback for the data, and performing retransmission according to the feedback, according to one embodiment of the present disclosure.

[0267] Referring to FIG. 9, TB1 (900) is initially transmitted in slot 0 (902), and ACK / NACK feedback (904) for this is transmitted in slot 4 (906). If the initial transmission of TB1 fails and a NACK is received, retransmission (910) for TB1 may be performed in slot 8 (908). The timing at which the ACK / NACK feedback is transmitted and the timing at which retransmission is performed may be predetermined or may be determined according to values ​​indicated in control information or / and upper layer signaling.

[0268] Figure 9 illustrates an example in which TB1 through TB8 are sequentially scheduled and transmitted starting from slot 0. This may be, for example, where TB1 through TB8 are each assigned HARQ process IDs 0 through 7 and transmitted. If the number of HARQ process IDs available to the base station and terminal is only 4, transmission for 8 different TBs may not be possible consecutively.

[0269] FIG. 10 is a diagram illustrating an example of a communication system using a satellite according to one embodiment of the present disclosure.

[0270] Referring to FIG. 10, a terminal (1001) transmits a signal to a satellite (1003) via a service link, and the satellite (1003) can forward the signal to a base station (1005) (e.g., a gateway) via a feeder link. The base station (1005) can be connected to a public data network via a core network (1009). The base station (1005) processes the received signal and transmits a signal including a request for a subsequent action to the terminal (1001), which can then be transmitted to the terminal (1001) via the satellite (1003). Since the distance between the terminal (1001) and the satellite (1003) is far, and the distance between the satellite (1003) and the base station (1005) is also far, the time required for data transmission and reception from the terminal (1001) to the base station (1005) ultimately becomes longer.

[0271] FIG. 11 is a diagram illustrating the Earth orbital period of a communication satellite according to the altitude or height of the satellite according to one embodiment of the present disclosure.

[0272] Referring to Figure 11, satellites for communication can be classified into low Earth Orbit (LEO), middle Earth Orbit (MEO), and geostationary Earth Orbit (GEO) satellites depending on their orbits. Generally, GEO (1100) refers to a satellite with an altitude of approximately 36,000 km, MEO (1110) refers to a satellite with an altitude of 5,000 to 15,000 km, and LEO refers to a satellite with an altitude of 500 to 1,000 km. The Earth orbital period varies depending on each altitude. For GEO (1100), the Earth orbital period is approximately 24 hours, for MEO (1110), it is approximately 6 hours, and for LEO (1130), it is approximately 90 to 120 minutes. Low Earth orbit (~2,000 km) satellites have an advantage over geostationary orbit (36,000 km) satellites in terms of propagation delay (which can be understood as the time it takes for a signal transmitted from a transmitter to reach a receiver) and loss due to their relatively low altitude.

[0273] FIG. 12 is a diagram illustrating a concept of satellite-terminal direct communication according to one embodiment of the present disclosure.

[0274] Referring to FIG. 12, a satellite (1200) positioned at an altitude of 100 km or higher by a rocket can transmit and receive signals with a ground terminal (1210) and transmit and receive signals with a ground station (1220) connected to a ground base station (e.g., DU (digital unit) farms) (1230).

[0275] FIG. 13 is a diagram illustrating a utilization scenario of satellite-terminal direct communication according to one embodiment of the present disclosure.

[0276] Referring to Fig. 13, satellite-terminal direct communication can support specialized communication services in a form that complements the coverage limitations of terrestrial networks. For example, by implementing a satellite-terminal direct communication function in a user terminal, transmission and reception of emergency rescue and / or disaster signals for users outside of terrestrial network communication coverage are possible (1300), mobile communication services can be provided to users in areas where terrestrial network communication is not possible, such as ships and / or aircraft (1310), real-time tracking and control of the locations of ships, trucks and / or drones, etc., without border restrictions (1320), and by supporting a satellite communication function in a base station, it is possible to utilize satellite communication to function as a backhaul of the base station and perform the backhaul function when physically distant (1330).

[0277] FIG. 14 is a diagram illustrating an example of calculating an expected data transmission rate (throughput) in an uplink when a LEO satellite at an altitude of 1200 km and a terminal on the ground perform direct communication according to one embodiment of the present disclosure.

[0278] Referring to Fig. 14, if the effective isotropic radiated power (EIRP) of the ground terminal in the uplink is 23 dBm, the path loss of the wireless channel to the satellite is 169.8 dB, and the satellite receiving antenna gain is 30 dBi, the achievable signal-to-noise ratio (SNR) is estimated to be -2.63 dB. In this case, the path loss may include path loss in space, loss in the atmosphere, etc. Assuming that the signal-to-interference ratio (SIR) is 2 dB, the signal-to-interference and noise ratio (SINR) is calculated to be -3.92 dB, and in this case, if a 30 kHz subcarrier spacing and 1 PRB frequency resource are used, a transmission rate of 112 kbps can be achieved.

[0279] FIG. 15 is a diagram illustrating an example of calculating an expected data transmission rate (throughput) in an uplink when a GEO satellite at an altitude of 35,786 km and a terminal on the ground perform direct communication according to one embodiment of the present disclosure.

[0280] Referring to Fig. 15, if the ground terminal's transmission power EIRP in the uplink is 23 dBm, the path loss of the wireless channel to the satellite is 195.9 dB, and the satellite receiving antenna gain is 51 dBi, the achievable SNR is estimated to be -10.8 dB. In this case, the path loss may include path loss in space and loss in the atmosphere. Assuming that the SIR is 2 dB, the SINR is calculated to be -11 dB, and in this case, if a 30 kHz subcarrier spacing and a frequency resource of 1 PRB are used, a transmission rate of 21 kbps may be achieved, which may be the result of performing three repeated transmissions.

[0281] FIG. 16 is a diagram illustrating a path loss value according to a path loss model between a terminal and a satellite according to one embodiment of the present disclosure, and a path loss according to a path loss model between a terminal and a terrestrial network communication base station.

[0282] Referring to Figure 16, d corresponds to distance and f c is the frequency of the signal. In free space where communication between a terminal and a satellite is performed, the path loss (FSPL, 1600) is inversely proportional to the square of the distance, but on the ground where air exists, where communication between a terminal and a terrestrial gNB is performed, the path loss (PL2, PL') is inversely proportional to the square of the distance. Uma-NLOS , 1610, 1620) is inversely proportional to almost the fourth power of the distance. d 3D means the straight-line distance between the terminal and the base station, and h BS is the height of the base station, h UT is the height of the terminal. d' BP = 4 xh BS xh UT xf c / c is calculated, where fc is the center frequency in Hz and c is the speed of light in m / s.

[0283] In satellite communications (or Non-Terrestrial Networks, NTN), the Doppler shift, or frequency shift (offset) of the transmitted signal occurs as the satellite continuously moves rapidly.

[0284] FIG. 17 is a diagram illustrating a formula and result for calculating the amount of Doppler shift experienced by a signal transmitted from a satellite when received by a ground user according to the altitude and position of the satellite and the position of a terminal user on the ground, according to one embodiment of the present disclosure.

[0285] Referring to Figure 17, the Earth's radius is R, h is the satellite's altitude, v is the speed at which the satellite orbits the Earth, and fc is the frequency of the signal. The speed of the satellite can be calculated from the altitude of the satellite, which is the speed at which the gravitational force, which is the force that pulls the satellite towards the Earth, and the centripetal force generated as the satellite orbits become equal, and this can be calculated as shown in Fig. 18.

[0286] Fig. 18 is a diagram illustrating the velocity of a satellite calculated at the altitude of the satellite according to one embodiment of the present disclosure. As can be seen in Fig. 17, the angle α is the elevation angle. As it is determined by the elevation angle The value of the Doppler shift is determined accordingly.

[0287] FIG. 19 is a diagram illustrating the Doppler shift experienced by different terminals within a single beam transmitted to the ground by a satellite according to one embodiment of the present disclosure.

[0288] Referring to Figure 19, the elevation angle The Doppler shift experienced by terminal 1 (1900) and terminal 2 (1910) according to the present disclosure were calculated, respectively. These results are based on the assumption that the center frequency is 2 GHz, the satellite altitude is 700 km, the diameter of one beam from the ground is 50 km, and the speed of the terminal is 0. In addition, the Doppler shift calculated in the embodiments of the present disclosure ignores the effect of the Earth's rotation speed, which can be considered to have a small effect because it is slow compared to the satellite's speed.

[0289] FIG. 20 is a diagram illustrating the difference in Doppler shift occurring within one beam depending on the position of a satellite determined from an elevation angle according to one embodiment of the present disclosure.

[0290] Referring to Figure 20, it can be seen that the difference in Doppler shift within the beam (or cell) is greatest when the satellite is positioned directly above the beam, i.e., when the elevation angle is 90 degrees. This may be because when the satellite is positioned above the center, the Doppler shift values ​​at one end of the beam and the other end have positive and negative values, respectively.

[0291] Meanwhile, satellite communication has a large delay time compared to terrestrial network communication because the satellite is far from the user on the ground.

[0292] FIG. 21 is a diagram illustrating a delay time from a terminal to a satellite and a round-trip delay time between a terminal, a satellite, and a base station according to the position of the satellite determined by the altitude angle, according to one embodiment of the present disclosure.

[0293] Referring to Figure 21, reference numeral 2100 represents the delay time from the terminal to the satellite, and reference numeral 2110 represents the round-trip delay time between the terminal, satellite, and base station. In this case, the delay time between the satellite and base station is assumed to be the same as the delay time between the terminal and the satellite.

[0294] FIG. 22 is a diagram illustrating a maximum difference value of round-trip delay time that varies depending on the user's position within one beam according to one embodiment of the present disclosure.

[0295] Referring to Figure 22, when the beam radius (or cell radius) is 20 km, the difference in round-trip delay time to the satellite experienced by terminals at different locations within the beam depending on the location of the satellite can be seen to be approximately 0.28 ms or less.

[0296] In satellite communications, when a terminal transmits and receives signals with a base station, it may mean that the signals are transmitted via a satellite. That is, in the downlink, the base station transmits a signal to the satellite, which then receives and transmits the signal to the terminal. In the uplink, the satellite receives a signal transmitted by the terminal and then transmits it to the base station. In the above, the satellite may perform only a frequency shift after receiving the signal and then transmit it. Alternatively, it may perform signal processing, such as decoding and re-encoding, based on the received signal before transmitting it.

[0297] For LTE or NR, the terminal can connect to the base station through the following procedure.

[0298] - Step 1: The terminal receives a synchronization signal (or a synchronization signal block (SSB), which may include a broadcast signal) from the base station. The synchronization signal may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The synchronization signal may include information such as slot boundaries, frame numbers, downlink, and uplink settings of a signal transmitted by the base station. In addition, through the synchronization signal, the terminal can obtain subcarrier offsets, scheduling information for transmitting system information, etc.

[0299] - Step 2: The terminal receives system information (System Information Block: SIB) from the base station. The SIB may include information for initial access and random access. The information for performing random access may include resource information for transmitting a random access preamble.

[0300] - Step 3: A random access preamble (or message 1, msg1) is transmitted to the random access resource set in Step 2. The preamble may be a signal determined based on the information set in Step 2 using a predetermined sequence. The base station receives the preamble transmitted by the terminal. The base station attempts to receive the preamble set in the resource set by the base station itself without knowing which terminal transmitted the preamble, and if the reception is successful, it can know that at least one terminal transmitted the preamble.

[0301] - Step 4: When the preamble is received in Step 3, the base station transmits a random access response (RAR, or message 2, msg2) in response thereto. The terminal that transmitted the random access preamble in Step 3 can attempt to receive the RAR transmitted by the base station in this step. The RAR is transmitted on the PDSCH, and the PDCCH that schedules the PDSCH is transmitted together with or in advance. A CRC scrambled with an RA-RNTI value is added to the DCI that schedules the RAR, and the DCI (and CRC) are channel-coded and then mapped to the PDCCH and transmitted. The RA-RNTI can be determined based on the time and frequency resources on which the preamble in Step 3 is transmitted.

[0302] The maximum time limit until the terminal that transmitted the random access preamble in step 3 receives the RAR in this step can be set in the SIB transmitted in step 2. This can be set to a maximum of 10 ms or 40 ms, for example. That is, if the terminal that transmitted the preamble in step 3 does not receive the RAR within a time determined based on the set maximum time of 10 ms, for example, the preamble can be transmitted again. The RAR can include scheduling information that allocates resources for a signal to be transmitted by the terminal in the next step, step 5.

[0303] FIG. 23 is a diagram illustrating an example of an information structure (MAC payload) of RAR according to one embodiment of the present disclosure. This may also be the MAC payload format of Msg B (fallback RAR).

[0304] Referring to FIG. 23, RAR (2300) may be, for example, a MAC PDU, and may also include information (2310) about timing advance (TA) to be applied by the terminal and a temporary C-RNTI value (2320) to be used from the next step.

[0305] * R field: A reserved bit, which can be set to "0", for example.

[0306] * Timing Advanced Command (TA) field (2310): The Timing Advanced Command field is an index value T used to control the amount of timing adjustment that the MAC entity should apply. A . The size of the above timing advance command field is, for example, 12 bits.

[0307] * UL Grant field: The UL Grant field indicates the resources to be used in the uplink, and the size of the UL Grant field is, for example, 27 bits.

[0308] * Temporary C-RNTI field (2320): The temporary C-RNTI field indicates a temporary identifier used by the MAC entity during random access, and the size of the temporary C-RNTI field is, for example, 16 bits.

[0309] - Step 5: The terminal that received the RAR in Step 4 transmits Message 3 (msg3) to the base station according to the scheduling information included in the RAR. The terminal may include its own unique ID value in msg3 and transmit it. The base station may attempt to receive msg3 according to the scheduling information it transmitted in Step 4.

[0310] - Step 6: The base station receives msg3, verifies the ID information of the terminal, and then generates message 4 (msg4) including the ID information of the terminal and transmits it to the terminal. The terminal that transmitted msg3 in step 5 can then attempt to receive msg4 to be transmitted in step 6. The terminal that receives msg4 can compare the ID value included in msg4 after decoding it with the ID value transmitted by the terminal in step 5 to determine whether the msg3 transmitted by the terminal was received by the base station. There may also be a limit to the time between the terminal transmitting msg3 in step 5 and receiving msg4 in this step, and this maximum time may also be set from the SIB in step 2.

[0311] When applying the initial access procedure using the above steps to satellite communications, the propagation delay time required in satellite communications can be a problem. For example, in step 3, the terminal transmits a random access preamble (or PRACH preamble), and in step 4, the period (random access window) during which the RAR can be received, i.e., the maximum time it takes to receive it, can be set via ra-ResponseWindow. In conventional LTE or 5G NR systems, this maximum time can be set to a maximum of 10 ms.

[0312] FIG. 24 is a diagram illustrating an example of a relationship between a PRACH preamble configuration resource and an RAR reception time point of an LTE system according to an embodiment of the present disclosure, and FIG. 25 is a diagram illustrating an example of a relationship between a PRACH preamble configuration resource and an RAR reception time point of a 5G NR system according to an embodiment of the present disclosure.

[0313] Referring to FIG. 24, in the case of LTE, a random access window (2410) starts 3 ms after transmitting (2400) a PRACH (random access preamble), and if the terminal receives (2420) a RAR within the random access window, it can be determined that the transmission of the PRACH preamble was successful.

[0314] Referring to FIG. 25, in the case of NR, a random access window (2510) starts from the control information area for RAR scheduling that appears for the first time after transmitting (2500) a PRACH (random access preamble). If a terminal receives (2520) a RAR within the random access window, it can be determined that the transmission of the PRACH preamble has been successful.

[0315] For example, TA for uplink transmission timing in a 5G NR system can be determined as follows. First, T c = 1 / ( f max ·N f ) is determined, and here f max = 480·10 3 Hz and N f = 4096. K = T s / T c = 64, T s = 1 / ( f ref ·N f,ref ), f ref = 15·10 3 Hz, N f,ref = can be defined as 2048 respectively.

[0316] FIG. 26 is a diagram showing the timing difference between downlink and uplink according to one embodiment of the present disclosure.

[0317] Referring to Figure 26, the timing of a downlink frame (2602) and an uplink frame (2604) in a terminal is illustrated. The terminal transmits an uplink frame (2604) based on the timing of the downlink frame (2602). TA = (N TA + N TA,offset )T c Uplink transmission can be performed as early as T above. TA The value of can be passed through RAR or determined based on MAC CE, and N TA,offset may be a value set to the terminal or determined based on a predetermined value.

[0318] In RAR of 5G NR system, T A You can indicate the value, in this case, T A may indicate one of the values ​​0, 1, 2, ..., 3846. In this case, the subcarrier spacing (SCS) of RAR is 2. μ ·If 15 kHz, N TA is N TA = T A ·16·64 / 2 μ is determined. After the terminal completes the random access process, it can receive a change value of TA from the base station, which can be indicated through MAC CE, etc. T indicated through MAC CE A The information can indicate one of the values ​​0, 1, 2, ..., 63, which is added to or subtracted from the existing TA value to calculate a new TA value, and the resulting TA value is N TA_new = N TA_old + (T A -31)·16·64 / 2 μ It can be newly calculated as follows. The TA value indicated in this way can be applied to uplink transmission by the terminal after a certain period of time.

[0319] FIG. 27 is a drawing for explaining the movement of a satellite according to one embodiment of the present disclosure.

[0320] Referring to FIG. 27, as a satellite (2702) orbits the Earth along a satellite orbit, the continuous movement of the satellite relative to a terminal (2704) located on the Earth's ground or on the Earth is illustrated. Since the distance between the terminal (2704) and the satellite (2702) varies depending on the elevation angle at which the terminal (2704) views the satellite (2702), the propagation delay between the terminal (2704), the satellite (2702), and the base station (2706) varies.

[0321] FIG. 28 is a drawing illustrating an example of the structure of an artificial satellite according to one embodiment of the present disclosure.

[0322] Referring to FIG. 28, a satellite (2800) may include a solar panel or solar array (2800) for solar or solar thermal power generation, a main mission antenna (2810) for transmitting and receiving antennas for communication with a terminal, a feeder link antenna (2820) for transmitting and receiving antennas for communication with a ground station, and an inter-satellite link antenna (2830) for transmitting and receiving antennas for inter-satellite communication. If inter-satellite communication is not supported, the antenna (2830) for transmitting and receiving signals between satellites may be omitted. Although the L band of 1 to 2 GHz is illustrated here as being used for communication with a terminal, it may also be possible to use high-frequency bands such as the K band (18 to 26.5 GHz), Ka band (26.5 to 40 GHz), and Ku band (12 to 18 GHz).

[0323] In various embodiments of the present disclosure, the term "base station (BS)" may refer to any component (or set of components) configured to provide wireless access, such as a transmit point (TP), a transmit-receive point (TRP), an enhanced node B (eNodeB or eNB), a 5G base station (gNB), a macrocell, a femtocell, a WiFi access point (AP), or other wireless enabled devices, based on the type of wireless communication system. The base stations may provide wireless access according to one or more wireless protocols, such as 5G 3GPP new radio interface / access (NR), long term evolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc.

[0324] In various embodiments of the present disclosure, the term "terminal" may represent any component such as "user equipment (UE), "mobile station," "subscriber station," "remote terminal," "wireless terminal," "receive point," or "user device." For convenience, the term "terminal" is used to represent a device that accesses a base station in various embodiments of the present disclosure, regardless of whether the terminal should be considered a mobile device (such as a mobile phone or a smart phone) or a stationary device (such as a desktop computer or a vending machine).

[0325] In various embodiments of the present disclosure, the term “TA” may be used interchangeably with “TA information,” “TA value,” or “TA index.”

[0326] In various embodiments of the present disclosure, data or control information transmitted by a base station to a terminal may be referred to as a first signal, and an uplink signal associated with the first signal may be referred to as a second signal. For example, the first signal may include DCI, UL grant, PDCCH, PDSCH, RAR, etc., and the second signal associated with the first signal may include PUCCH, PUSCH, msg 3, etc.

[0327] There may be an association between the first signal and the second signal. For example, if the first signal is a PDCCH including a UL grant for uplink data scheduling, the second signal corresponding to the first signal may be a PUSCH including uplink data. Meanwhile, the gap between the times at which the first signal and the second signal are transmitted and received may be a value pre-determined between the terminal and the base station. Alternatively, the gap between the times at which the first signal and the second signal are transmitted and received may be determined by an instruction from the base station or by a value transmitted through upper layer signaling.

[0328] In direct terminal-satellite communication, the distance between the terminal and the satellite and the satellite and the base station is long, and the satellite is constantly moving. Therefore, when a signal transmitted by a base station or terminal is received by the terminal or base station, a time offset due to delay time occurs. Therefore, embodiments of the present disclosure provide a method and device for a base station to indicate time offset information and for a terminal to correct the time offset accordingly, so as to correct the time offset.

[0329] The following embodiments assume communication between a terminal and a satellite and a ground station, but do not exclude the possibility of communication between a satellite base station and a terminal. In the embodiments of the present disclosure, the term "time offset" may be used interchangeably with "timing advance." The methods and devices provided in the various embodiments of the present disclosure can be applied not only to satellite communication systems but also to terrestrial communication systems.

[0330] [First embodiment]

[0331] In the first embodiment of the present disclosure, when a terminal transmits an uplink signal to a satellite or a base station, a method and apparatus for directly determining (for example, calculating) a TA value by the terminal itself and applying the determined TA value are described. In the first embodiment of the present disclosure, a method and apparatus for allowing the base station or satellite to indicate to the terminal a TA value to be applied when the terminal transmits an uplink signal to a satellite or a base station, and thus allowing the terminal to transmit the uplink signal by applying the indicated TA value are described. In the first embodiment of the present disclosure, a method and apparatus for adaptively determining a TA value to be applied when the terminal transmits an uplink signal to a satellite or a base station are described. In the first embodiment of the present disclosure, a method and apparatus for adaptively selecting one of a method in which a terminal determines a TA value by itself and a method in which a base station or satellite indicates a TA value to the terminal as described in the present disclosure and the terminal applies the indicated TA value are described.

[0332] The terminal compares the uplink transmission time with the downlink reception time for uplink synchronization, and based on the comparison result, sets the uplink transmission time to T later than the downlink reception time. TA It can be brought forward as much as T calculated for TA for satellite communication TA can be expressed as in the following mathematical formula 5.

[0333]

[0334] In the above mathematical expression 5, T c is T c = 1 / ( f max ·N f ) can be given as, f max = 480·10 3 Hz and N f = 4096. In the above mathematical expression 5, N TA T included in RAR or MAC CE received from base station A It is a value determined based on values, etc., and N TA,offset can be a pre-fixed or promised value. In the above mathematical expression 5, N TA,UE-specific is the TA correction value (e.g., terminal-specific TA correction value) measured by the terminal based on the position (or reference position) of the terminal itself and the satellite, and N TA,common may be a TA correction value (e.g., common TA offset) set or indicated by the base station using upper signaling or physical layer signals.

[0335] The above mathematical expression 5 is compared with the mathematical expression 6 below, which is a conventional TA application method. TA,UE-specific Wow N TA,common It may be a formula with added parameters.

[0336]

[0337] FIG. 29 is a diagram illustrating a terminal in an initial connection according to an embodiment of the present disclosure. TA This is a diagram showing an example of the process of determining .

[0338] Figure 30 is a timing diagram illustrating a procedure for determining parameters for a TA according to an embodiment of the present disclosure. The illustrated procedure starts from the initial connection when the terminal is N TA , N TA,UE-specific and N TA,common An example of the process of determining is described.

[0339] Referring to Figure 29, the terminal is N TA =0 is applied to transmit the PRACH preamble (2902) to the base station, and the base station transmits N TA RAR (2904) is transmitted to the terminal, which indicates N. After that, the terminal TA =A is applied to transmit PUSCH (2906), and the base station N TA transmits MAC CE (2908) indicating N to the terminal. After that, the terminal sends N TA =A+ N TA Apply to transmit PUSCH (2910).

[0340] Referring to Figure 30, the base station provides satellite information and N TA,common and setting information (3002) including drift rate (e.g. satellite information and N TA,common ) is transmitted to the terminal. After that, the terminal sends N TA Assuming =0, N measured by yourself TA,UE-specifi c and set N TA,common The PRACH preamble (3004) is transmitted to the base station by applying the N TA Send RAR (3006) indicating N to the terminal, TA,UE-specifi c and N TA,common can be updated. After that, the terminal will be N TA Assuming =A, T is calculated according to mathematical formula 5 TA According to the PUSCH (3008), the base station transmits N TA MAC CE (3010) indicating the destination is transmitted to the terminal. After that, N TA,UE-specifi c and N TA,common can be updated, and the terminal is N TA =A+ N TA Updated N by applying TA,UE-specifi c and N TA,common T calculated according to mathematical formula 5 by applying TA PUSCH (3012) is transmitted accordingly.

[0341] T TA is transmitted in RAR or msg B A = Based on 0, 1, 2, ..., 3846, T TA = T A ·16·64 / 2 μ can be determined as . Also, T as MAC CE A = 0, 1, 2,..., 63 are transmitted, N TA_new = N TA_old + (T A - 31)·16·64 / 2 μ can be updated. Also, f max , N f , T transmitted in RAR or msg B A or T transmitted from MAC CE A The values ​​may change depending on the communication system. And the T transmitted from the MAC CE A Based on N TA_new = N TA_old + (T A - M)·16·64 / 2 μ When the terminal performs a TA update as follows, if T A If the maximum value for is greater than 63, the value of M may be greater than or equal to 31, and T A If the maximum value for is less than 63, the terminal updates the above N based on the M value being less than or equal to 31. TA value(=N TA_new ) can also be determined.

[0342] Figure 31 is a schematic diagram illustrating another example of the operation process of a terminal in a communication system according to one embodiment of the present disclosure. The terminal performs an initial connection procedure according to the process described in Figure 31, and after performing the initial connection procedure, it can determine a TA, which is described in detail below.

[0343] Referring to FIG. 31, in operation 3111, the terminal detects a synchronization signal and PBCH block (SSB) received from a base station. In operation 3113, the terminal decodes system information blocks (SIBs) based on the detected SSBs. Here, the terminal can detect information about random access channel (RACH) resources by decoding the SIBs.

[0344] In operation 3115, the terminal obtains (or decodes) satellite information by decoding SIBs. Here, the satellite information may include at least one of various parameters such as satellite position information. In operation 3115, the terminal obtains a UE-specific TA correction value, for example, N, based on the position (or reference position) of the terminal itself and the satellite based on the obtained satellite information. TA,UE-specific can be obtained. In operation 3117, the terminal decodes the SIBs to obtain a common TA offset, for example, N TA,common Obtain (or decode) .

[0345] At action 3119, the terminal is N TA,UE-specific Wow N TA,common TAs can be calculated based on the calculated TAs, and a PRACH is transmitted to the base station by applying the calculated TAs. In operation 3121, the terminal receives an RAR including a TA value as a response to the PRACH transmission. In operation 3123, the terminal adjusts the TA based on the received RAR.

[0346] In operation 3125, the terminal transmits msg3 to the base station by applying TA. Here, msg3 represents a message transmitted on the UL-SCH, including a C-RNTI MAC CE or CCCH SDU as part of a random access procedure, and may be the first scheduled transmission of the random access procedure. In operation 3127, the terminal receives a MAC CE including a TA adjustment value from the base station. In operation 3129, the terminal transmits a PUSCH or / and a PUCCH by applying TA based on the TA adjustment value included in the MAC CE.

[0347] The operation process of the terminal as described in FIG. 31, that is, the process of performing the initial connection procedure and determining the TA after performing the initial connection procedure, can be summarized as shown in Table 24 below when compared with the operation process of the terminal in other embodiments of the present disclosure.

[0348] The operation process of the terminal is also based on 31. 1. SSB detection 2. Decoding SIBs (RACH resource information detection) 3. PRACH transmission 4. RAR reception including TA value 5. TA adjustment based on RAR 6. Transmitting msg3 by applying TA 7. MAC CE reception including TA adjustment value 8. PUSCH / PUCCH transmission by applying TA based on TA adjustment value 1. SSB detection 2. SIB decoding (RACH resource information detection) 3. Satellite information (location information, etc.) decoding, N TA,UE-specific Acquisition 4. Common TA offset decoding, N TA,common 5. Transmit PRACH by applying TAs 6. Receive RAR containing TA values ​​7. Adjust TA based on RAR 8. Transmit msg3 by applying TAs 9. Receive MAC CE containing TA adjustment values ​​10. Transmit PUSCH / PUCCH by applying TAs

[0349] In addition, the order of some operations in the operation process of the terminal described in FIG. 31 may be changed, and for example, the order of the operation of decoding satellite information and the operation of decoding common TA offset may be changed. Meanwhile, although the operation process of the terminal in the communication system according to various embodiments of the present disclosure is illustrated with reference to FIG. 31, it is to be understood that various modifications may be made to FIG. 31. For example, although FIG. 31 illustrates consecutive steps, it is to be understood that the steps described in FIG. 31 may overlap, occur in parallel, occur in a different order, or one or more steps may occur multiple times.

[0350] FIG. 32 is a diagram schematically illustrating another example of an operation process of a terminal in a communication system according to one embodiment of the present disclosure.

[0351] Referring to FIG. 32, the terminal may perform an initial access procedure according to the process described in FIG. 32, and determine a TA after performing the initial access procedure, which is described in detail as follows. In particular, FIG. 31 illustrates an operation process of a terminal based on a random access procedure for a 4-step random access (RA) type, and the operation process of the terminal illustrated in FIG. 32 may be an operation process of a terminal based on a random access procedure for a 2-step RA type.

[0352] First, in operation 3211, the terminal detects an SSB received from the base station. In operation 3213, the terminal decodes SIBs based on the detected SSBs. Here, the terminal can obtain information about RACH resources by decoding the SIBs.

[0353] In operation 3215, the terminal obtains (or decodes) satellite information by decoding SIBs. Here, the satellite information may include at least one of various parameters such as satellite position information. In operation 3215, the terminal obtains a UE-specific TA correction value, for example, N, based on the position (or reference position) of the terminal itself and the satellite based on the decoded satellite information. TA,UE-specific can be obtained. In operation 3217, the terminal decodes the SIBs to obtain a common TA offset, for example, N TA,common Obtain (or decode) .

[0354] At action 3219, the terminal is N TA,UE-specific Wow N TA,common Based on the TAs, the UE calculates TAs and transmits msgA to the base station by applying the calculated TAs. Here, msgA may be preamble and payload transmissions of a random access procedure for a 2-step random access (RA) type. In operation 3221, the UE receives msgB including a TA value from the base station. Here, msgB may include response(s) for contention resolution, fallback indication(s), and backoff indication as a response to msgA in the random access procedure for the 2-step RA type. In operation 3223, the UE adjusts the TA based on the TA adjustment value included in msgB. In operation 3225, the UE transmits a PUSCH or / and a PUCCH by applying the adjusted TA.

[0355] The operation process of the terminal as described in FIG. 32, that is, the process of performing the initial connection procedure and determining the TA after performing the initial connection procedure, can be summarized as shown in Table 25 below when compared with the operation process of the terminal in other embodiments of the present disclosure.

[0356] The operation process of the terminal is also based on 32. 1. SSB detection 2. Decoding SIBs (RACH resource information detection) 3. Transmitting MsgA (PRACH + Msg3) 4. Receiving MsgB containing TA value 5. Adjusting TA based on MsgB 6. Transmitting PUCCH / PUSCH by applying TA 1. SSB detection 2. Decoding SIBs (RACH resource information detection) 3. Decoding satellite information (location information, etc.), N TA,UE-specific Acquisition 4. Common TA offset decoding, N TA,common 5. Transmit MsgA by applying TAs 6. Receive MsgB containing TA values ​​7. Adjust TA based on MsgB 8. Transmit PUCCH / PUSCH by applying TAs

[0357] In addition, the order of some operations in the operation process of the terminal described in FIG. 32 may be changed, and for example, the order of the operation of decoding satellite information and the operation of decoding common TA offset may be changed. Meanwhile, although the operation process of the terminal in the communication system according to various embodiments of the present disclosure has been disclosed with reference to FIG. 32, it is to be understood that various modifications may be made to FIG. 32. For example, although FIG. 32 illustrates consecutive steps, it is to be understood that the steps described in FIG. 32 may overlap, occur in parallel, occur in a different order, or one or more steps may occur multiple times.

[0358] N used in embodiments of the present disclosure TA,UE-specific may be a value calculated and applied by the terminal. Therefore, the base station may calculate N calculated by the terminal. TA,UE-specific The value may not be known. Also, N calculated by the terminal in this way TA,UE-specific Values ​​may change over time due to movement of the satellite or terminal.

[0359] In embodiments of the present disclosure, the base station may have N that may vary over time. TA,UE-specificIt may be necessary to control the TA of the terminal by considering the value, and thus the terminal may be N TA,UE-specific It may be necessary to set the point in time at which the value is updated. Therefore, the terminal may set N based on one of the following methods, for example, one of Methods 1-1 to 1-6, or a method combining at least two of Methods 1-1 to 1-6. TA,UE-specific You can update the value.

[0360] - Method 1-1: The terminal always receives N whenever an SIB containing satellite information (e.g., including satellite information, etc.) is received. TA,UE-specific Method 1-1 can be applied when the terminal determines that SIB is received from the base station or when a paging signal instructing SIB update is received from the base station.

[0361] - Method 1-2: Base station is TA, for example N TA,UE-specific The rate of change of TA can be separately instructed, and also the cycle and offset for updating the TA value, for example, recalculating the TA value according to the rate of change of TA, can be set. In this case, the terminal updates the TA, for example, N, at a time determined according to the cycle and offset. TA,UE-specific The amount of TA updated by the terminal may be determined based on the rate of change of the TA. In various embodiments of the present disclosure, the base station may indicate the rate of change of the TA based on an explicit or implicit method.

[0362] - Method 1-3: The base station determines whether the terminal is N based on the satellite's location and the terminal's location. TA,UE-specificThe update cycle and offset for updating the TA can be set. In this case, the terminal can update the TA at the corresponding time determined according to the update cycle and offset set by the base station. In various embodiments of the present disclosure, the base station can indicate the update cycle and offset based on an explicit or implicit method.

[0363] - Method 1-4: The terminal performs uplink transmission (e.g., PUCCH / PUSCH, PRACH, SRS transmission, etc.) at least in some cases (performed every time, or at regular intervals, or at irregular times), for example, N at the slot time. TA,UE-specific You can always update and apply it.

[0364] - Method 1-5: The terminal determines N based on the time when the TA command transmitted by the base station through MAC CE expires. TA,UE-specific updates. For example, when the TA expires, the terminal TA,UE-specific Update. The expiration mentioned above may mean that the timer value has reached a certain point in time based on the timer for the TA command. The timer may be set to timeAlignmentTimer and may be a parameter regarding how long the uplink time synchronization lasts. When a new TA command is received, the terminal may start or restart timeAlignmentTimer. When timeAlignmentTimer expires, the terminal may empty the HARQ buffer and reconfigure RRC settings, etc.

[0365] - Method 1-6: N TA,UE-specific A new timer timeAlignmentTimer_UEspecific is introduced, and the terminal can use N based on the new timer timeAlignmentTimer_UEspecific. TA,UE-specificcan be updated. timeAlignmentTimer_UEspecific is when the terminal is N TA,UE-specific Recalculate or N TA,UE-specific When transmitting information about the UE to the base station, it can be started or restarted. When timeAlignmentTimer_UEspecific expires, the UE is N TA,UE-specific Update by recalculating or N TA,UE-specific can be set to 0, or PRACH transmission can be performed.

[0366] [Second Embodiment]

[0367] A second embodiment provides a method and device for a terminal to transmit (report) a timing advance (TA) value that it is applying or has applied to a base station or satellite. In the present disclosure, a "satellite" may be an object located high above the ground, and may include aircraft, airships, and the like.

[0368] A terminal may perform an operation to transmit the TA value it is applying to the base station. This may be to inform the base station of the applied TA value when the terminal applies the TA value without a separate instruction from the base station, or to confirm or determine how the terminal is applying the TA value indicated by the base station. For example, this operation may be performed when the satellite to which the terminal is connected changes so that the newly connected satellite can check the terminal's TA value. For example, the terminal may independently apply a TA calculated based on the positions of the terminal and the satellite.

[0369] A terminal may use one or a combination of two or more of the following methods to report a TA value to a base station.

[0370] - Method 2-1: The base station can trigger the TA value reporting of the terminal through DCI. The base station can trigger the TA value reporting through some bit field values ​​of the DCI or a combination of bit field values. If a field indicating the TA value reporting trigger is included in the DCI and in this case, if the above-mentioned field of the received DCI is set to a specific value, the terminal can understand that the TA value reporting is triggered. Alternatively, if the value of one or more fields (for example, for other purposes) included in the DCI is set to a predetermined value, the terminal can understand that the TA value reporting is triggered. The terminal can transmit the TA value at a specific point in time based on the point in time when the DCI is received to the base station.

[0371] - Method 2-2: The base station can trigger the terminal's TA value reporting through the MAC CE. The base station can trigger the TA value reporting using some bit values ​​or bit field values ​​of the MAC CE, and the terminal can transmit the TA value at the time of receiving the MAC CE or at a certain time after the time of receiving the MAC CE to the base station.

[0372] - Method 2-3: The base station can instruct the terminal which TA value to report through RRC configuration. For example, the base station can determine the time point at which the terminal reports the TA value by setting the period and offset value for TA reporting and / or specific conditions for the terminal to report the TA value through upper signaling, and in this case, the reference TA value application time (i.e., the time at which the TA value to be reported is applied, which can be referred to as the TA value reference time point) can also be specified. The specific conditions for the terminal to report the TA value in the above may be, for example, when the TA value is greater than or equal to a certain value, or when the distance between the terminal and the satellite is greater than or equal to a certain value, and the above-mentioned specific values ​​may be set by upper signaling, information transmitted in SIB, etc., or may be fixed values.

[0373] - Method 2-4: The terminal can report the TA value without a separate trigger from the base station. For example, Method 4 may be that the terminal transmits information indicating the TA value to the base station according to a specific condition, and the specific condition may be a condition that is predetermined, such as a time for performing TA value reporting (without signaling such as DCI, MAC CE, RRC, etc. for triggering from the base station) or a condition regarding the result of comparing the TA value applied by the terminal with a specific threshold value, etc.

[0374] When transmitting TA values ​​as described above, the terminal may transmit the TA value information to the base station using a physical channel such as PUCCH or PUSCH, or via higher-level signaling. When the terminal transmits the TA value information using a physical channel, the resources to be used for reporting the TA value information may be configured via higher-level signaling.

[0375] Reporting the TA value above means that T in the above mathematical formula TA value or N TA,UE-specific It may be that the value is reported. Or, T TA Wow N TA,UE-specific The base station can configure which of these to report to the terminal through SIB or higher-level signaling.

[0376] The reference time for determining the TA value reported by the terminal and the time for reporting the TA value can be determined based on the time at which the terminal performs the TA value report, the time at which the TA value report is triggered, etc. For example, if the TA value report is triggered by DCI in slot n, the terminal can report the TA value applied or calculated in slot nK, and the terminal can report the TA value to the base station in slot n+N. In the above, K and N can be values ​​determined according to subcarrier spacing, UE capability, DL / UL settings of the slot, PUCCH resource settings, etc., respectively.

[0377] In the above, K may be 0. K=0 may mean that the terminal reports the TA value based on the time point when the TA value reporting triggering signal is received. In addition, K in the above may be a value smaller than 0, in which case, for example, the TA value at the time point when the terminal reports the TA value may be calculated in advance, report information may be generated, and reported. In addition, K may be an integer value greater than 0. This may mean that the terminal reports the TA value at a time point earlier than the time point when the terminal reports the TA value (for example, slot n+N). This may be because the terminal needs time to encode the information to be reported and prepare for transmission, so it may report the TA value at an early time point.

[0378] FIGS. 33 and 34 are diagrams illustrating an example of operations of a base station and a terminal for reporting a TA value of a terminal according to one embodiment of the present disclosure. When reporting a TA value, the TA value applied by the terminal may be indicated in units of ms, slots, or symbols, or may be provided in the form of information including decimal points rather than integers. The report of a TA value may include an absolute value of the TA, but may also include a TA value indicated from a previous base station, a relative TA value excluding a predetermined TA value, or a change in the TA value (which may be, for example, a change in TA over a certain period of time).

[0379] FIG. 33 is a diagram illustrating the operation of a base station according to one embodiment of the present disclosure.

[0380] Referring to FIG. 33, the base station transmits configuration information related to TA reporting through upper layer signaling (3300). This configuration information may include at least one of information for configuring TA reporting, such as a period and offset at which TA reporting is to be performed, a TA reporting trigger condition, information on a TA value reference point in time, the type of TA information to be reported, and resource configuration information for which TA reporting is to be performed. The base station triggers a TA report to the terminal (3310). This trigger may be performed, for example, through upper layer signaling or DCI of the specific content described above, but may also be omitted. The base station receives the TA report transmitted by the terminal according to the transmitted configuration information (3320).

[0381] FIG. 34 is a diagram illustrating the operation of a terminal according to one embodiment of the present disclosure.

[0382] Referring to FIG. 34, the terminal receives configuration information related to a TA report transmitted by a base station through upper layer signaling (3430). This configuration information may include at least one of information for configuring a TA report, such as a period and offset at which the TA report is to be performed, a TA report trigger condition, information on a TA value reference point in time, the type of TA information to be reported, and resource configuration information on which the TA report is to be performed. The terminal receives a signal for triggering a TA report transmitted by the base station (3440). This trigger may be performed, for example, by upper layer signaling or DCI of the specific content described above, but may also be omitted. The terminal transmits a TA report according to the received configuration information (3420). For example, if the terminal receives TA report resource information, it transmits a TA report on the configured resource.

[0383] Each step disclosed in FIGS. 33 and 34 may be applied with the order changed, and other steps may be added or omitted.

[0384] [Third Embodiment]

[0385] In the third embodiment, N described through the first and second embodiments TA,UE-specific Provides a method for the terminal to calculate, determine and report the N TA,UE-specific The value may be calculated based on the terminal's distance from itself and a non-terrestrial network (NTN) satellite. The terminal may calculate its position by receiving signals from navigation satellites in a satellite navigation system, and the navigation satellites may be different from the NTN satellites.

[0386] The terminal can estimate the delay time between the satellite and the terminal based on its own position and the satellite's position, and can perform uplink transmission by correcting the estimated delay time value on its own. For example, a satellite transmits information about its own position through broadcast information, and the terminal can receive the information about the satellite's position transmitted by the satellite and compare it with its own position. The terminal's own position can be determined independently or in combination using information from one of several types of Global Positioning System (GPS) systems or base stations. Through the comparison, the terminal can estimate the time it takes for a radio wave to propagate to the satellite and calculate the uplink transmission time.

[0387] For example, if a terminal receives a signal in slot n in downlink at a specific point in time and needs to perform uplink transmission corresponding to the signal in slot n+k, the uplink transmission can be transmitted 2*Td earlier than slot n+k. In the above, Td may be a delay time from the terminal to the satellite calculated using the position information of the satellite and the terminal, or a value corresponding thereto. The delay time Td may be a value obtained by dividing the distance from the terminal to the satellite or a value corresponding thereto by the speed of light, or a value corresponding thereto. In the above, the position of the satellite may be a value calculated based on slot n+k in which the terminal performs uplink transmission, for example. This is because the position of the satellite in slot n and the position of the satellite in slot n+k may differ depending on the movement of the satellite.

[0388] In terrestrial networks, propagation delay times of less than 1 ms occur considering the distance to the base station of up to about 100 km, but in satellite networks, the distance to the satellite can be thousands of km, and the distance from the satellite to the base station can also be thousands of km, so the delay time can be much greater than in the case of terrestrial networks.

[0389] FIG. 35 is a diagram illustrating an example of a difference in propagation delay time between a terrestrial network and a satellite network according to one embodiment of the present disclosure.

[0390] Referring to Figure 35, in satellite network communication, the delay time may vary depending on the altitude and orbit of the satellite. For example, when the satellite altitude is 700 km, the distance between the terminal and the satellite and the round trip time of the radio wave are shown according to the altitude angle. In the case of the satellite network, a low-orbit satellite is assumed, and when the altitude angle is 0 to 180°, the radio round trip time (radio RTT, which may include the round trip time for a signal to be transmitted between a transmitter and receiver and the processing time at the other node) may range from 40.9 ms to 9.3 ms. The above delay time is only an example and may vary depending on the altitude and orbit of the satellite. For example, the average delay time may increase at high altitudes.

[0391] In terrestrial networks, since the maximum delay time is within 1 or 2 ms, the timing advance provided by LTE and 5G NR systems can be used to match the slot timing for transmitting the downlink from the base station's perspective with the slot timing for receiving the uplink (i.e., the indices of the DL slot and the UL slot can match). In other words, if the terminal performs uplink transmission ahead of the downlink timing by the timing advance value indicated by the base station, the uplink signal transmitted by the terminal will match the downlink timing of the base station when received by the base station. On the other hand, in satellite networks, it is impossible to match the slot timing for transmitting the downlink from the base station's perspective with the slot timing for receiving the uplink using the timing advance provided by the existing LTE and 5G NR systems. This is because the propagation delay time in the satellite network is on the order of tens of ms, which is larger than the maximum value of the timing advance provided by the existing LTE and 5G NR systems.

[0392] A satellite navigation system may also be referred to as a Global Navigation Satellite System (GNSS), and the GNSS may include, for example, the GPS of the United States, the GLONASS of Russia, the Galileo of the EU, and the BeiDou of China. The GNSS may include a Regional Navigation Satellite System (RNSS), and the RNSS may include, for example, the Indian Regional Navigation Satellite System (IRNSS) of India, the Quasi-Zenith Satellite System (QZSS) of Japan, and the Korean Positioning System (KPS) of Korea. A signal transmitted from the GNSS may include at least one of auxiliary navigation information, a normal operation status of a satellite, satellite time, satellite ephemeris, satellite altitude, reference time, and information about various correction data.

[0393] In embodiments of the present disclosure, an NTN satellite may be a communication satellite that transmits signals for a terminal to connect to a base station. In various embodiments of the present disclosure, a GNSS satellite may be a satellite that transmits signals of a satellite navigation system. The terminal may receive signals from one or more GNSS satellites, and may calculate its own location based on the signals received from the one or more GNSS satellites, and may identify a reference time for each of the one or more GNSS satellites.

[0394] If the terminal can calculate its own location multiple times based on signals received from multiple GNSS satellites, the terminal can calculate its own actual location based on an average of the multiple locations, a location corresponding to a received signal with the strongest intensity among the multiple locations, or an average of the multiple locations based on signal intensity (for example, a method of applying a weight to a location corresponding to a signal with a strong signal intensity). Here, the method of calculating the terminal's own location based on signals received from multiple GNSS satellites can be implemented in various forms, and a detailed description thereof will be omitted.

[0395] In embodiments of the present disclosure, the time acquired from the GNSS or the time of the base station transmitted by the base station may be based on, for example, Coordinated Universal Time (UTC) time, which may be based on the time from 00:00:00 on January 1, 1900 in the Gregorian calendar. This may vary depending on the type of GNSS system, and a reference time zone as shown in Table 26 below may be used.

[0396]

[0397] In Table 26 above, NavIC may mean NAVigation with Indian Constellation, QZS may mean Quasi Zenith Satellite, QZSS may mean Quasi-Zenith Satellite System, QZST may mean Quasi-Zenith System Time, SBAS may mean Space Based Augmentation System, and BDS may mean BeiDou Navigation Satellite System.

[0398] A base station can indicate, via satellite, the type of GNSS system that serves as the basis for the location or time information used by the base station itself, and can use an indicator such as that shown in Table 27 below, for example.

[0399]

[0400] As described above, the terminal can calculate the time required for a signal to be transmitted from an NTN satellite to the terminal based on its own location calculated by the terminal and the location of the NTN satellite received from the NTN satellite, and can determine a TA value based on this. When determining the TA value, the terminal can also consider the distance from the NTN satellite to a ground base station, or, if the signal is transmitted to the ground base station via another NTN satellite, the distance from the NTN satellite to another NTN satellite.

[0401] In contrast, the terminal can obtain reference time information from information transmitted by a GNSS satellite, compare the time information transmitted by an NTN satellite with the reference time information obtained from the GNSS satellite, and calculate the time required (propagation delay) from the NTN satellite to the terminal based on the comparison result.

[0402] The location and time information of NTN satellites can be transmitted from base stations to terminals via SIB. This may be transmitted directly by the NTN satellites.

[0403] The distance between the terminal and the satellite or its corresponding value is d UE,sat (unit km) and the speed of light is v c (Unit: km / sec), N TA,UE-specific is d UE,sat / v c (unit: sec) can be determined based on. For example, NTA,UE-specific = It can be determined and applied as Integerize the value to N TA,UE-specific is a method that can be determined by. Or / and additionally, the terminal is N in a method such as a combination of at least one of the following three methods. TA,UE-specific Decide on N TA,UE-specific It will be able to report information to the base station.

[0404] - Method 3-1: N TA,UE-specific = (D+a) / T c , D is an integer, and a is a prime number greater than or equal to 0 and less than 1. Here, And, That is, this method can be a method of dividing the propagation delay between the terminal and the satellite into integer and decimal parts, and reporting only the integer or its corresponding value, or reporting the integer and decimal or its corresponding values, respectively. By using this method, the number of bits used to report the propagation delay can be reduced. Here, the decimal part is T in the above. c It was explained to be an integer multiple of 16·64·T c / 2 μ It can be determined to be a multiple of .

[0405] In the above, μ may mean the subcarrier spacing of the current carrier or BWP, or the related CORESET. Or, it may be a value used for transmitting and receiving signals such as PDSCH or PUSCH. Here, μ=0,1,2,3,4,5 may be values ​​corresponding to the subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, 120 kHz, 240 kHz, and 480 kHz, respectively. Or, μ may be N TA,UE-specificIt can be set through upper signaling from the base station for decision. Alternatively, μ can be used as a fixed value, for example, it can be used as one of the values ​​0, 1, 2, 3, 4, 5, such as μ=5.

[0406] - Method 3-2: N TA,UE-specific Ga 16·64·T c / 2 μ It can be determined to be a multiple of . This is It can be determined as follows. In this disclosure can mean the largest integer not greater than x, which can be rounded down to the integer unit, i.e. discarding the decimal value. In this method, Instead of rounding down using , rounding up or down from a decimal place can be used instead. In the above, μ can mean the current carrier or the subcarrier spacing of the BWP, SIB, or the related CORESET. Or, it can be a value used in a transmit / receive signal such as a PDSCH or PUSCH.

[0407] Here, μ=0,1,2,3,4,5 can be values ​​corresponding to the subcarrier spacing of 15 kHz, 30 kHz, 60 kHz, 120 kHz, 240 kHz, 480 kHz, respectively. Or μ is N TA,UE-specific can be set via upper signaling from the base station for the decision. Or μ can be used as a fixed value, for example, μ = 5 can be used. Or the above N TA,UE-specific The μ to be used in the calculation can be set separately by the base station through SIB or higher-level signaling.

[0408] - Method 3-3: N TA,UE-specific = T A,UE-specific ·16·64 / 2 μ , and T in the above A,UE-specific is N TA,UE-specific Go d UE,sat / v c ·T cIt can be set to an integer that makes it closest to . Or, N TA,UE-specific d UE,sat / v c ·T c It can be determined as the minimum integer that satisfies N, or TA,UE-specific d UE,sat / v c ·T c It can be set to the maximum integer that satisfies .

[0409] - Method 3-4: N depending on base station settings TA,UE-specific = can be set to 0. This is because the propagation delay occurring in the link between the terminal and the satellite (which can be called a service link) is almost the same for the terminals within the coverage area of ​​a specific beam of the satellite, so the conventional TA mechanism and N TA,common This may be because uplink time synchronization can be achieved with the terminal N TA,UE-specific Value N TA,UE-specific = 0 or N calculated based on the position of the satellite and terminal and the speed of light according to the GNSS signal TA,UE-specific The base station can set whether to use the value through SIB. As another example, the base station calculates N based on the time when the terminal transmits the PRACH preamble based on the position of the satellite and the terminal and the speed of light according to the GNSS signal. TA,UE-specific Whether to continue to use the value until further instructions or settings are made, or to recalculate N for each uplink transmission. TA,UE-specific The value to be used can be set by SIB or separate RRC signaling. That is, in the above mathematical expression 5, as follows: N TA,UE-specific It may be a matter of setting a value.

[0410] N TA,UE-specific is UE self-estimated TA to pre-compensate for the service link delay if configured, and NTA,UE-specific is 0 otherwise.

[0411] In the above methods 3-1 to 3-4, N is determined based on the distance between the terminal and the satellite (or its corresponding value) and the speed of light. TA,UE-specific The methods for determining are only examples and there may be more diverse methods. For example, in general, N TA,UE-specific When defining a value as an integer or defining an expression based on an integer value, to represent it as a multiple of a specific integer or rational number value K. or It can also be expressed as, where K can be a predetermined value or a value determined by signaling parameters.

[0412] Method 2: K = 16·64 / 2 μ This means that if K is μ or T c It may be determined by at least one of the same system parameters. In this way, N TA,UE-specific Instead of having a somewhat sparse granularity for values, it has the advantage of being able to express more diverse values ​​with the same bit signaling. In addition, in each of the above methods, Instead of using the floor operation like this, we round up to the decimal place ( ) or the rounding operation round(x).

[0413] [Example 4]

[0414] In the fourth embodiment, N described through the first and second embodiments TA,common It provides a method for a base station to transmit data to a terminal and for the terminal to calculate and apply the data.

[0415] Below, the base station sets and instructs the terminal to N TA,commonThis is a method by which a base station transmits information to a terminal, and at least one or more of these methods can be applied in combination.

[0416] - Method 4-1: The base station can set an offset value to the terminal through RRC signaling. This set value is N A,common and based on this, N TA,common can be decided.

[0417] - Method 4-2: The base station can instruct the terminal to have one offset value through MAC CE. This set value is N A,common and based on this, N TA,common can be determined. This method is different from the case of using the above method 4-1 in that the base station and the terminal are N TA,common There is an advantage in that the base station and the terminal can clearly determine the point in time when applying the MAC CE. For example, N can be applied after a certain period of time from the point in time when the MAC CE is received or the point in time when an ACK for the reception of the MAC CE is transmitted. TA,common This can be applied. For example, the base station can send N in msec units through MAC CE 8 bits. A,common By passing N, you can indicate from 0ms to 255ms. In this case, N TA,common is N TA,common = N A,common / (1000·T c ) is determined as follows.

[0418] - Method 4-3: The base station can set one or more offset values ​​to the terminal through upper layer signaling. Alternatively, these values ​​can be preset. This preset value is N. A,common These are candidate values, and the base station can indicate one of them through MAC CE.

[0419] - Method 4-4: The base station can set an offset value to the terminal through SIB. This set value is N A,commonand based on this, N TA,common can be determined. Using this value, the terminal calculates and applies the TA when transmitting the PRACH preamble during the initial connection process. Afterwards, through the MAC CE N A,common is directed to the terminal, and the terminal uses this to N TA,common For example, it can be calculated as follows.

[0420] N TA,common(new) = N TA,common(old) + ( N A,common - x)·y

[0421] In the above, x and y are N A,common It can be determined based on the number of bits and units for transmission. For example, it can be determined as follows.

[0422] N TA,common(new) = N TA,common(old) + ( N A,common - M)·16·64 / 2 μ

[0423] Here, the M value can be 31, which can be indicated via MAC CE. N A,common If the maximum value of the value is greater than 63, it may be greater than or equal to 31, N A,common If the maximum value of the value is less than 63, it may be less than or equal to 31.

[0424] - Method 4-5: The base station can instruct the terminal to have one offset value through MAC CE. This set value is N A,common and based on this, N TA,common can be determined. This method is better than the above method 4-1 in that N between the base station and the terminal TA,commonThere is an advantage in that the application time can be clarified. For example, N can be applied after a certain period of time from the time of receiving the MAC CE or the time of transmitting an ACK for receiving the MAC CE. TA,common This can be applied. For example, the base station can transmit 16·64·T through MAC CE about 19 bits or 24 bits. c / 2 μ N in sec A,common will be able to convey. At this time, N TA,common is N TA,common = N A,common ·16·64· / 2 μ It is determined as follows. The number of bits of MAC CE may be a different number than the above example.

[0425] - Method 4-6: The base station can instruct the terminal to have one offset value through MAC CE. This set value is N A,common and, along with this, based on the altitude of the satellite, N TA,common can be determined. This method has the advantage of reducing the number of bits to be transmitted compared to the case of using the above method 4-5. For example, the base station can transmit 16·64·T through MAC CE about 16 bits. c / 2 μ N in sec A,common will be able to convey. At this time, N TA,common is determined as follows:

[0426]

[0427] h from above sat is the altitude of the satellite. This means that when the satellite is at a certain altitude, the minimum distance between the terminal and the satellite is the above-mentioned certain altitude, so the base station only needs to calculate the remaining additional distance N. A,common It may mean signaling through. The number of bits of MAC CE may be a different number than the above example.

[0428] In the above formula (h sat / v c )·1 / T c The values ​​can also be defined by integerization or rationalization in a similar manner to the third embodiment. For example, In addition to integerization or rationalization using a rounding operation such as d in the third embodiment, UE,sat h instead of value sat Various integerization or rationalization methods can be applied based on the value. Of course, (h sat / v c )·1 / T c + T Acommon ·16·64 / 2 μ A similar integerization or rationalization as described above can also be applied to the entire value. For example, It can also be defined as, in this case, In K=16·64 / 2 μ It is the same method as considering it. In addition, the operation used for the above integerization or rationalization can apply various other operations such as rounding up, rounding down, and not just rounding down.

[0429] - Method 4-7: The base station receives N at the time of transmission through SIB. TA,common Value and N TA,common The change rate information can be transmitted. The above information can be transmitted to a specific terminal through RRC signaling rather than SIB, and the transmission method may vary depending on the status of the terminal (RRC_idle, RRC_inactive, RRC_connected).

[0430] N TA,common The rate of change information could be conveyed through the SIB via one, two or three parameters.

[0431] For example, if the rate of change information is transmitted as one parameter A, N is transmitted as SIB. TA,common Let t1 be the time point at which the data is transmitted, and t2 be the time point at which uplink transmission is performed, then N to be applied by the terminal at t2 TA,commoncan be calculated as follows:

[0432] N TA,common(t2) is N TA,common(t2) = N TA,common(t1) + (t2-t1)·A

[0433] At this time, the units of t1 and t2 are msec and the unit of A can be Tc / msec. That is, what A means is how many Tc per 1 msec N TA,common It can indicate whether the value has changed.

[0434] As another example, if the rate of change information is transmitted as two parameters A and B, N is transmitted as SIB. TA,common Let t1 be the time point at which the data is transmitted, and t2 be the time point at which uplink transmission is performed, then N to be applied by the terminal at t2 TA,common Ind can be calculated as follows:

[0435] N TA,common(t2) is N TA,common(t2) = N TA,common(t1) + (t2-t1) 2 ·B + (t2-t1)·A

[0436] That is, when the change rate information is transmitted through n parameters, it is also possible to express it in the form of an nth-order polynomial for the difference between two points in time (t2-t1). In this case, the units of t1 and t2 are msec, the unit of A is Tc / msec, and the unit of B can be Tc / msec^2. In other words, what A means is how many Tc per 1 msec is N TA,common What does B mean, if the value has changed, how many Tc per 1 msec is N TA,common It can indicate whether the rate of change of a value has changed.

[0437] [Example 5]

[0438] The fifth embodiment is a parameter K for determining the timing at which a terminal transmits a second signal in response to a first signal transmitted by a base station. offset Provides a method and device for transmitting a signal from a base station to a terminal.

[0439] When a base station transmits a first signal, it indicates the timing at which a terminal transmits a corresponding second signal using upper signaling and DCI. For example, when transmitting a PDSCH, HARQ-ACK feedback for it can be indicated by an HARQ-ACK timing-related indicator in the bit field of the DCI that scheduled the PDSCH. In satellite communication, since the delay time between the terminal and the base station is very large, the offset value indicated in the conventional DCI may not be able to indicate the correct timing. Therefore, the base station may indicate an additional timing offset, the K, through SIB. offset The value is transmitted to the terminal, and the terminal receives the offset K offset In addition, the transmission timing of the second signal (uplink transmission) can be determined.

[0440] When the terminal is in the RRC_connected state after the initial connection, the base station provides K to the terminal. offset The value can be updated through RRC signaling. However, if the update is performed only through RRC signaling, the base station and the terminal may have different K values ​​during the time period when RRC reconfiguration is performed. offset In this case, the correct transmission and reception of the second signal may not be achieved. To eliminate this ambiguity time interval, the base station may provide the terminal with multiple K offset Set the value and K set above as MAC CE offset It may indicate one of the values. Therefore, the terminal will receive the updated K from a predetermined point in time after receiving the MAC CE. offset You can apply values.

[0441] For example, through RRC signaling, K is assigned according to the index as shown in Table 28 below. offset You can set candidate values ​​for the value.

[0442]

[0443] [Table 28] shows K through 8 indices. offset This is an example of setting at regular intervals, and various other settings are also possible. If the values ​​of index i are 0, 1, 2, ..., 2 M 2 like -1 M (M is an integer such as 2, 3, 4, ...) and K for index i offset Value K offset (i), for i > 0, K offset (i) = K offset It can also be defined to have evenly spaced values, such as (0) + (i - 1)*A (where A is a positive constant). Of course, the value of M can be variable depending on the system settings, and the value of A can also be set variably depending on the value of M. In addition, some of the indices can be defined as reserved fields. K excluding reserved fields offset The maximum value of K offset (i max ), when A = (K offset (i max ) - K offset (0)) / i max There may be a relationship.

[0444] Of course, this is just an example of values ​​set to uniform differences, and in general, it may not be composed of values ​​with uniform differences overall. For example, depending on the range of the index, it may be set to different values ​​with different differences as follows: (i m The value is simply 2 M-1 ) may be set to , and may generally be set to another integer value.)

[0445] 1 i < i m ,

[0446] K offset (i) = K offset (0) + (i - 1)*A1

[0447] im ≤ i≤ i max ,

[0448] K offset (i) = K offset (i m ) + (i - i m )*A2

[0449] A1, A2 are different positive constants, and A1 = (K offset (i m ) - K offset (0)) / i m , A2 = (K offset (i max ) - K offset (i m )) / (i max - i m ),

[0450] After this, the base station transmits the index to the terminal through MAC CE in slot n, and the terminal transmits the index to the terminal in slot n+k. offset The transmission of the second signal can be performed by applying the k value above, which may be set or determined according to the subcarrier spacing.

[0451] In the above embodiments, the terminal can receive GNSS information (e.g., auxiliary navigation information, satellite normal operation status, satellite time, satellite ephemeris, satellite altitude, reference time, information on various correction data, or at least one of GNSS system types) provided by the satellite through the GNSS function. The terminal equipped with the GNSS function can calculate the distance between the terminal and the satellite based on the terminal's location information determined based on the GNSS information and the satellite's location information acquired through a separate upper signal or L1 signal, and thereby determine the delay time between the terminal and the satellite. Therefore, when applying TA, it may be possible to utilize the GNSS information.

[0452] On the other hand, if the terminal is not equipped with a GNSS function, it may be difficult for the terminal to compensate for the delay between the terminal and the satellite through the above-mentioned operation.

[0453] FIG. 36 is a diagram showing the change in distance between terminals belonging to the same coverage (or beam) within a satellite and a satellite according to one embodiment of the present disclosure.

[0454] Fig. 36(a) shows a case where the position of the satellite (3602) is at an elevation angle of 90 degrees with respect to the beam center of the satellite (3602), and Fig. 36(b) shows a case where the position of the satellite (3602) is at an elevation angle of 30 degrees with respect to the beam center of the satellite (3602). Terminal 1 (3604) is located at the center of each beam, and terminal 2 (3606) is located at the beam boundary. When the altitude of the satellite (3602) is 600 km, the distance between terminal 1 (3604) and the satellite (3602) in Fig. 36(a) is approximately 600 km. The distance between terminal 1 (3604) and the satellite (3602) in Fig. 36(b) is approximately 1075.5 km. As the distance between terminal 1 (3604) and terminal 2 (3606) increases, the difference between (the distance between satellite (3602) and terminal 1 (3604)) and (the distance between satellite (3602) and terminal 2 (3604)) will become larger.

[0455] [Table 29] below is a diagram showing the difference in distance and delay time from satellite (3602) for terminal 1 (3604) and terminal 2 (3606) within the same coverage of satellite (3602) in FIG. 36(a).

[0456] Distance between terminal 1 and terminal 2 (km) Distance between satellite and terminal 2 (km) Difference between (distance between satellite and terminal 1) and (distance between satellite and terminal 2) (km) Difference between (delay between satellite and terminal 1) and (delay between satellite and terminal 2) (ms) 10600.080.080.0002725600.50.50.00175060220.0067100608.38.30.0277

[0457] [Table 30] below is a diagram showing the difference in distance and delay time from the satellite for terminal 1 (3604) and terminal 2 (3606) within the same coverage of satellite (3602) in FIG. 36(b).

[0458] Distance between terminal 1 and terminal 2 (km) Distance between satellite and terminal 2 (km) Difference between (distance between satellite and terminal 1) and (distance between satellite and terminal 2) (km) Difference between (delay between satellite and terminal 1) and (delay between satellite and terminal 2) (ms) 10 10 66.85 17.30.0 57725 1053.9 243.16 0.14450 1032.58 60.287 100990.16 170.68 0.568

[0459] In the above [Table 29] and [Table 30], the difference between (satellite-terminal 1 delay time) and (satellite-terminal 2 delay time) increases as the distance between terminal 1 and terminal 2 increases, that is, as the beam radius provided by the satellite increases. In the above [Table 29] and [Table 30], the difference between (satellite-terminal 1 delay time) and (satellite-terminal 2 delay time) may vary depending on the elevation angle between the satellite and terminal 1. Therefore, if two different terminals existing within the same beam are not in the same position, the distance between the satellite and the terminal may vary, and this difference may vary depending on the radius of the beam and the elevation angle between the satellite and the terminal. A terminal equipped with a GNSS function can receive only the position information of the satellite to confirm the position information of the satellite, and compensate for the delay time according to the distance difference between the satellite and the terminal by considering the position information of the terminal and the position information of the satellite. However, if a terminal without a GNSS function does not properly compensate for the difference in delay time, there is a possibility that signals transmitted between different terminals from a satellite or base station receiving end may cause interference.

[0460] Figure 37 is a conceptual diagram showing a method for a terminal having a GNSS function to transmit by applying TA according to one embodiment.

[0461] Referring to FIG. 37, a terminal (3702) may be equipped with a GNSS function. As shown in reference number 3700, in a situation where the beam radius is 50 km and the altitude of a satellite (3704) is 600 km, a terminal (3702) at the beam boundary can confirm that the distance between the satellite (3704) and the terminal (3702) is 602 km and determine the delay time as the value obtained by dividing the distance between the satellite and the terminal by the speed of light. As shown in reference number 3710, when the terminal (3702) transmits an uplink signal at a time (3712) to which a TA value considering the delay time is applied, the satellite (3704) can receive the uplink signal at a time (3714) corresponding to a desired slot or timing.

[0462] Accordingly, the satellite (3704) can receive signals transmitted by multiple terminals (e.g., multiple terminals equipped with GNSS functions) without interference through the same receiver, without having to implement a separate receiver for each terminal. That is, since multiple terminals within a single beam radius adjust TA by considering different satellite-terminal distances and different delay times caused thereby, it is possible to receive the corresponding signals at the same time from the satellite receiver's perspective even if the transmission timing of each terminal is different.

[0463] Figure 38 is a conceptual diagram showing a method for a terminal without a GNSS function to transmit by applying TA according to one embodiment.

[0464] Referring to FIG. 38, the terminal (3802) may not be equipped with a GNSS function. In a situation where the satellite (3804) is positioned as shown in reference numeral 3800, it may be difficult for the terminal (3802) to determine whether the terminal (3802) is at the center of the beam area of ​​the satellite (3804) or at the beam boundary. Since the base station can know which point (e.g., reference position R) the beam transmitted by the satellite (3804) is centered on, the base station can transmit information about the point (e.g., reference position R) to the terminal (3802) through an upper signal. The terminal may be able to calculate the distance between the reference position (R) and the satellite (3804) based on the information (e.g., reference position information) and adjust the TA value in consideration of the calculated value (e.g., 600 km).

[0465] As shown in reference number 3810, if it is known that the distance between the satellite and the terminal is 602 km, the terminal (3802) can transmit an uplink signal at a specific point in time (3812), and the satellite (3804) can receive the uplink signal at a designated point in time (3816).

[0466] However, if the terminal (3802) does not have a GNSS function, the terminal (3802) can transmit an uplink signal using a TA value (e.g., 600 km) calculated based on the reference position information received as a separate upper signal. As shown in reference number 3810, the terminal (3802) transmits an uplink signal at a time point (3814) determined by applying the TA value, but since the actual distance between the satellite and the terminal is 602 km, the receiver of the satellite (3804) receives the uplink signal at a time point (3818) that is delayed from the point intended by the satellite. The receiver of the satellite (3804) may not accurately receive the uplink signal actually transmitted by the terminal (3802) and may perform a blind search for a certain period of time.

[0467] Referring to reference number 3800, it is possible to compensate for the delay time due to the distance difference between the satellite and the terminal to some extent by providing reference position information indicating the reference position of the satellite (3804) to terminals within the beam radius. However, it is difficult to compensate for the exact delay time for each individual terminal. Therefore, it may be possible to compensate for the TA value more quickly through a method of indicating the reference position and an L1 signal.

[0468] In one embodiment, the terminal (3802) can obtain reference location information through SIB and transmit an uplink signal based on the reference location information. The satellite (3804) or base station can analyze the received uplink signal and transmit information about the TA value of the uplink signal to be transmitted next by the terminal (3802) by including it in the DCI that schedules the uplink signal. The terminal (3802) can update the TA value for transmitting the uplink signal by receiving the DCI.

[0469] In the case of a terrestrial network, the terminal can update the TA value through RAR or MAC CE. In the case of a satellite network, it may be necessary to update the TA more quickly because the distance between the satellite and the terminal may vary over time. In other words, as described in FIG. 26, the terminal calculates the T according to Equation 6 for the uplink frame (2604) based on the time point of the downlink frame (2602). TA = (N TA + N TA,offset )T c It can be transmitted as early as N above. TA The value of can be passed through RAR or determined based on MAC CE, and N TA,offsetmay be a value set to the terminal or determined based on a predetermined value according to a frequency band or a duplexing mode such as TDD / FDD. Alternatively, it may be possible to apply the following mathematical expression 7 instead of the above mathematical expression 6.

[0470]

[0471] Here, Tc has the same meaning as applied to mathematical expression 5 of the present disclosure.

[0472] For terminals with GNSS function, N TA1 is a value that compensates for the delay time between the satellite and the terminal, and is a value calculated by the terminal using the distance between the terminal and the satellite according to the location of the terminal and the location of the satellite. N TA2 is a value that compensates for the delay time between the satellite and the ground station, and may be provided as a constant value or in the form of a linear, quadratic, or cubic function with time as a variable.

[0473] For terminals without GNSS function, N TA1 is a value that compensates for the delay time between satellite and terminal or the delay time between ground station and terminal, and may be provided as a constant value or as a linear, quadratic or cubic function with time as a variable. Alternatively, N TA1 is a value that compensates for the delay time between the satellite and the terminal, and is a value calculated by the terminal using the distance between the terminal and the satellite using the reference position and the satellite position provided by the upper signal. N TA2 is provided through L1 signals such as DCI, and is a value used by terminals to compensate for delay time instantaneously.

[0474] The following examples provide a more detailed description of methods for more accurately compensating for the TA of terminals without GNSS capabilities. In the following description, satellites may be replaced with base stations or ground stations.

[0475] [Example 6]

[0476] Hereinafter, the method for indicating the reference position described in FIG. 38 will be described in the embodiment. The reference position is a parameter used by a terminal without GNSS functionality to roughly calculate the delay time between a satellite and the terminal, and it may be possible to consider at least one of the following methods.

[0477] - Method 6-1: Through SIB, a base station or satellite can provide reference position information indicating the reference position of the satellite to terminals within the satellite's beam area. The reference position information may be included in SIB1 or in an SIB exclusively used in a satellite communication network. In one embodiment, the reference position information may include information such as latitude, longitude, and altitude, such as (x, y, z). In one embodiment, the reference position information may include a time function that varies over time. In one embodiment, additional time-varying information (e.g., reference time information) may be provided to terminals. In one embodiment, the reference time information may be the start or end time of a slot, subframe, or frame in which the SIB is transmitted. In one embodiment, separate time information (e.g., delay time information) may be transmitted together with the SIB in which the reference position information is transmitted. The terminal may calculate a delay time using the reference position information and the satellite position information, and reflect the delay time in a TA to perform uplink transmission. The satellite position information may be included in the same SIB as the reference position information, or may be received by the terminal through another SIB.

[0478] - Method 6-2: It may be possible to provide information on the delay time between the reference position of the beam corresponding to the satellite and the satellite (e.g., delay time information or reference time information) (i.e., the TA value to be applied by the terminal) via SIB without providing information on the reference position. Accordingly, the terminal can adjust the TA using the delay time information between the satellite and the reference position received via SIB. In one embodiment, the satellite may directly provide information on the TA value to be applied by the terminal belonging to the beam served by the satellite, without providing the reference position and satellite position information. The information on the TA value may include information for compensating for the delay time between the satellite and the reference position, and / or additionally include information for compensating for the delay time between the satellite and the ground station. The delay time information may be provided in the form of a constant value, or in the form of a linear, quadratic, or cubic function with time as a variable. Information on the coefficients of each term of the function may be included and transmitted in the SIB information. Additionally, in the case of a function that uses time as a variable, the reference point of the function may be designated as the start or end point of the slot, subframe, or frame in which the SIB is transmitted or received, or reference time information indicating the reference point of the function may be included and transmitted together within the SIB.

[0479] In one embodiment, the delay time information may be provided in the form of a quadratic function, for example, a-(t-t0) 2 + b-(t-t0) 2+ c can be provided to the terminal in the form of a quadratic function. At this time, the reference time related to the quadratic function is t0, and the coefficients a, b, c of the function and a constant value (e.g., t0) can be provided through SIB. In one embodiment, the reference time of t0 can indicate the start time or the last time of the slot or subframe in which the SIB including the delay time information is transmitted.

[0480] [Example 7]

[0481] Hereinafter, the embodiment describes a method for adjusting TA through an L1 signal. As illustrated in FIG. 38 and described in the sixth embodiment above, even if reference position information or equivalent reference time information is provided to a terminal within a beam served by a satellite and the terminal applies the information to a TA value during uplink transmission, the delay time between the terminal and the satellite may not be accurately compensated, so that the satellite receiver may not receive the terminal's transmission signal at the exact time. Therefore, in order to apply a more accurate TA value, the satellite or base station may include information (e.g., a TA adjustment field) for updating the TA value previously applied by the terminal in the L1 signal (e.g., DCI) that schedules uplink transmission.

[0482] In one embodiment, a satellite or base station may be able to instruct a terminal to change a TA value applied in a previous uplink transmission through a TA adjustment field consisting of multiple bits (e.g., 6 bits) in a DCI format. In one embodiment, the TA adjustment field values ​​may be as shown in [Table 31], and the terminal may be able to reflect a new TA value through the following [Mathematical Formula 8].

[0483]

[0484] T Ais the value indicated by the TA adjustment field, and N TA_new is a TA value to be used for transmitting a scheduled uplink signal through DCI including a TA adjustment field. N TA_old is the TA value used by the terminal to transmit the uplink signal before receiving the DCI including the TA adjustment field. μ represents the subcarrier value, and 2 μ It refers to the subcarrier value corresponding to -15 kHz. Through the above mathematical expression 8, the terminal can perform TA adjustment in an accumulated manner.

[0485] TA adjustment fieldT A 00000000000011......1111106211111163

[0486] The above [Table 31] is only an example, and the bit size of the TA adjustment field and each T corresponding to each bit map A It may be possible to set an additional upper signal (e.g. RRC signaling). In [Table 31], the T of the TA adjustment field A As an example, the case where the granularity of T is 1 is given. A The granularity of can be 2 or 4 or any other natural number value. In one embodiment, the terminal does not consider the previously received TA value and adjusts the TA adjustment field (=T A ) when transmitting an uplink signal indicated by DCI, a new TA (=N TA,new ) to T A- 16-64 / 2 μ It can be determined as follows. At this time, T A The value of may be similar to [Table 31] or may be set to a different value. The terminal is T A can be used for TA adjustment in absolute mode.

[0487] In one embodiment, the DCI including the TA adjustment field may be included in a terminal-specific DCI format or a terminal-common DCI format. The terminal-specific DCI format refers to a DCI format that schedules a PDSCH, PUCCH, or PUSCH for the specific terminal. The terminal-common DCI format refers to control information that is commonly provided for all or part of terminal groups. In the case of the terminal-specific DCI format, the DCI format for scheduling the PDSCH and the DCI format for scheduling the PUSCH may be different, and since the DCI format for scheduling the PDSCH is usually indicated together with the PUCCH transmission, it can be utilized as information for TA adjustment of the corresponding PUCCH. The DCI format for scheduling the PUSCH can be utilized as information for TA adjustment of the PUSCH.

[0488] The above TA adjustment field may be configured with the same field value for the DCI format for scheduling the PDSCH and the DCI format for scheduling the PUSCH, or may be configured with field values ​​that are partially or entirely different values. In this case, it may be possible for different bit sizes to be applied. When TA adjustment information is provided in a terminal-common DCI format, a TA adjustment field that is commonly provided to the corresponding terminal groups may be provided, or a TA adjustment field applicable to each individual terminal may be combined and transmitted.

[0489] For example, if TA adjustment information is provided to five terminals in a terminal-common DCI format, the terminal-common DCI format may consist of a total of 30 bits, and it may be possible to sequentially apply TA adjustment fields for each terminal, each of 6 bits. Each terminal may be able to receive in advance, through an upper signal, the total bit size of the terminal-common DCI format and the start time and size information of the bits that the terminal itself must search for for TA adjustment.

[0490] The TA adjustment field value indicated through the terminal common DCI format or terminal specific DCI format may be applied to all uplink channels after the DCI including the corresponding TA adjustment field value is scheduled, or may be applied only to some or a specific group of specific uplink channels. Examples of specific uplink channels may include PUCCH, PUSCH, and SRS, and PUCCH may also be divided into Configured grant PUCCH, which is periodically transmitted without a separate DCI, and Dynamic grant PUCCH, which is scheduled with DCI, and applied respectively.

[0491] PUSCH can also be divided into Configured grant PUSCH, which is transmitted periodically without a separate DCI, and Dynamic grant PUSCH, which is scheduled with a DCI, and applied separately. As an example of application to a specific group, the TA adjustment field value included in the DCI format for scheduling a PUSCH means that it is applied only to the PUSCH scheduled in the corresponding DCI or only to other Dynamic grant PUSCHs. In other words, the TA adjustment field value does not apply to any other uplink signals or channels.

[0492] Alternatively, although the TA adjustment field described above is described as an independently existing DCI field of the DCI format, it may be possible for it to be implicitly determined through other DCI fields and their values ​​within the DCI format. For example, it may be possible for the TA adjustment value to be implicitly determined through time resource allocation information or frequency resource allocation information of the DCI format. Alternatively, it may be possible for the TA adjustment value to be implicitly determined through other information such as an MCS field, NDI, RV, or uplink transmission power information. Being implicitly determined means that when a specific DCI field value is indicated, the TA adjustment value to be updated or applied by the terminal is also determined. In this case, the information for this may be set in advance through a higher-order signal.

[0493] [Embodiment 8]

[0494] In the following embodiments, a method for reflecting the processing time of a terminal during uplink transmission by reflecting the TA adjustment value (e.g., TA adjustment field) indicated by the L1 signal described in the seventh embodiment is described. As described in [Mathematical Formula 3] or [Mathematical Formula 4], the terminal requires a minimum processing time to transmit a PUCCH or PUSCH. If a TA adjustment value is included in a DCI format for scheduling a PUCCH or PUSCH and the TA adjustment value must be reflected in the TA value of a PUCCH or PUSCH to be transmitted, processing time may be required to reflect the TA adjustment value. Therefore, in [Mathematical Formula 3], N1+d 1,1 +d 1,2 is N1+d 1,1 +d 1,2 +d 1,3 can be replaced by d in the modified [Equation 3]1,3 means the processing time required by the TA adjustment value, and is composed of x symbols, where x can have an integer value greater than or equal to 0. The above d 1,3 The value can be determined by terminal capability reporting.

[0495] Similarly, N1+d in [Equation 4] 2,1 is N1+d 2,1 +d 2,2 can be replaced by d in the modified [Equation 4] 2,2 means the processing time required to reflect the TA adjustment value, and is composed of x symbols, where x can have an integer value greater than or equal to 0. The above d 2,2 It may be possible to determine by terminal capability report. The calculation of processing time considering the above TA adjustment value is only an example, and it may be possible to consider processing time according to TA adjustment in various other ways. In one embodiment, even if the terminal receives the TA adjustment field, if it does not update the TA through the TA adjustment field, it may not be necessary to calculate the processing time considering the TA adjustment value indicated by the TA adjustment field. For example, in [Mathematical Formula 3] or [Mathematical Formula 4], d 1,3 or d 2,2 It may be possible for the value to be 0.

[0496] FIG. 39 is a flowchart showing a method for a terminal without a GNSS function to adjust TA according to one embodiment of the present disclosure.

[0497] Referring to FIG. 39, in operation 3902, the terminal may receive a synchronization signal from a base station or a satellite and receive higher layer signaling (e.g., first higher layer signaling information) related to a satellite network. The first higher layer signaling information may include reference position information and / or reference time information related to the satellite as described above. In one embodiment, the first higher layer signaling information may be included in a system information block (SIB). In operation 3904, the terminal may perform an initial connection by reflecting a TA that applies reference position information or reference time information included in the higher layer signaling information as described in the above-described embodiment.

[0498] After completing the initial connection, in operation 3906, the terminal may receive additional upper signal (e.g., second upper signaling information) from a base station or a satellite, and / or receive uplink scheduling information (e.g., DCI). In one embodiment, the terminal may identify that the DCI includes a TA adjustment field based on the second upper signal, and / or determine the bit size of the TA adjustment field included in the DCI and / or the corresponding T for each bit map. A can be identified.

[0499] In operation 3908, the terminal may perform uplink signal transmission using a value indicated in the TA adjustment field included in the uplink scheduling information (e.g., DCI) based on the additional upper signal.

[0500] Although a series of processes for achieving time synchronization is illustrated in FIG. 39, it may be possible to extend and consider a similar operation to the method of applying Doppler shift for achieving frequency synchronization described in the following ninth embodiment.

[0501] [Example 9]

[0502] Hereinafter, the embodiments describe a method for compensating for Doppler shift. The previously described embodiments described methods for achieving time synchronization during uplink transmission when a terminal lacks GNSS functionality. However, when a terminal lacks GNSS functionality, it is impossible to measure the terminal's precise location and thus its moving speed. Therefore, it may be difficult to achieve frequency synchronization during uplink transmission by considering the Doppler effect caused by the relative velocity between the satellite and the terminal. Therefore, a method for achieving frequency synchronization separately from time synchronization may be required.

[0503] As described above in Figure 38, when a satellite provides reference position information to a terminal, the terminal's moving speed is usually smaller than the satellite's moving speed, so it may be possible to compensate for the Doppler value to some extent, although not an exact value, based on information about the satellite's position and moving speed.

[0504] FIG. 40 is a diagram showing components necessary for calculating Doppler between a terminal and a satellite according to one embodiment of the present disclosure.

[0505] Referring to FIG. 40, when the position of a satellite (4004) and the velocity (or angular velocity) of the satellite at that position are known, the terminal (4002) may be able to calculate the Doppler shift value using [Mathematical Formula 9]. This is merely an example, and the terminal (4002) may be able to calculate the Doppler shift value using other mathematical formulas or methods.

[0506]

[0507] - F d : Doppler shift value

[0508] - F c : Frequency used for transmission

[0509] - c: Light velocity

[0510] - v: Satellite velocity

[0511] - : Angle between vector v and vector SM

[0512] - u: Angle between vector OM and vector OS

[0513] - (gamma) = (R+h) / R

[0514] - R: Earth radius

[0515] - h: satellite altitude

[0516] - α (alpha) is the elevation angle

[0517] In one embodiment, instead of providing information such as satellite position and reference position information to the terminal, the satellite provides a Doppler shift value (F) that should be commonly applied to the terminals within the beam. d ) may be provided as an upper signal or MAC CE. The upper signal may be SIB or terminal-specific RRC information. Through this, the Doppler shift value applied by the terminal to the uplink signal may not be exact, but it may be used to roughly synchronize the frequency.

[0518] Since the relative velocity experienced by terminals within the same beam relative to the satellite varies depending on the satellite's altitude and beam radius, the actual Doppler shift experienced by terminals during uplink transmission may also vary. Therefore, it may be possible to consider a method of adjusting the Doppler shift value using the L1 signal to achieve frequency synchronization, similar to a method of adjusting the TA value using the L1 signal to achieve time synchronization. The L1 signal may exist as a separate field in the DCI format or may be indicated together with another field.

[0519] In one embodiment, information for adjusting the Doppler shift value may be configured in the same field as the TA adjustment field, which indicates time synchronization. For example, a time / frequency sync field allows a terminal to simultaneously receive the TA value and Doppler shift value to be adjusted for uplink transmission.

[0520] [Table 32] is a table that shows how to adjust a Doppler shift value consisting of 3 bits, for example, when a separate Doppler shift value field exists. In [Table 32], the unit of the Doppler shift value can be Hz, the center frequency of the carrier on which the uplink is transmitted, or ppm (part per million, one millionth) based on the center frequency of the band. [Table 33] is a table that shows how to indicate the TA value and the Doppler shift value simultaneously through the time / frequency sync field, as an example. X, Y, W, Z, X1, Y1, W1, and Z1 described in [Table 32] and [Table 33] can be values ​​that are set in advance for each bitmap through an upper signal.

[0521] The terminal may apply either an accumulated or absolute method to the Doppler shift value indicated by the L1 signal. The accumulated method means that the terminal applies the Doppler shift value indicated by the L1 signal by accumulating it with the previously applied Doppler shift value, while the absolute method means that the terminal applies the Doppler shift value indicated by the L1 signal without considering the previously applied Doppler shift value.

[0522] Doppler shift fieldDoppler shift value (Hz, ppm)000X001Y.....110W111Z

[0523] Time / frequency sync fieldDoppler shift value (Hz, ppm)T A 000XX1001YY1.......110WW1111ZZ1

[0524] [Example 10] In the following, the embodiment describes a procedure for a terminal to adjust time and frequency synchronization for an uplink signal using an L1 signal.

[0525] FIG. 41 is a diagram illustrating a series of processes in which a terminal according to one embodiment receives each control information and transmits an uplink signal corresponding thereto.

[0526] Referring to FIG. 41, the terminal may sequentially receive first control information (4102) and second control information (4104). The control information (4102, 4104) may be in DCI format and may include information for scheduling the first uplink signal (4112) and the second uplink signal (4114), respectively. The first uplink signal (4112) may correspond to PUCCH, PUSCH, SRS, etc. The second uplink signal (4114) may correspond to PUCCH, PUSCH, SRS, etc.

[0527] In one embodiment, the first control information (4102) and the second control information (4104) may each include DCI fields for adjusting time and frequency synchronization, as described in the preceding embodiments. In this case, when transmitting the first uplink signal (4112), it is necessary to determine whether or not to consider, in addition to the information for adjusting time and frequency synchronization indicated in the first control information (4102), the information for adjusting time and frequency synchronization indicated in the second control information (4104).

[0528] If the information controlling time and frequency synchronization is in absolute mode, only the values ​​indicated in each control information (4102 or 4104) need to be applied. However, if the information controlling time and frequency synchronization is in accumulated mode, it is necessary to determine the reference interval of the information controlling time and frequency synchronization for determining the TA and Doppler shift values ​​determined by the terminal during uplink transmission.

[0529] For example, when transmitting the first uplink signal (4112), the terminal may be able to utilize information for adjusting the time and frequency synchronization accumulated up to the time of receiving the first control information (4102) that schedules the transmission. In this case, the time and frequency synchronization adjustment information indicated in the second control information (4104) is not applied to the TA and Doppler shift values ​​determined when transmitting the first uplink signal (4112).

[0530] As another example, when transmitting the first uplink signal (4112), the terminal may be able to utilize information for adjusting time and frequency synchronization accumulated up to immediately before the transmission of the first uplink signal (4112) (or before the immediately preceding reference X symbol). In this case, the time and frequency synchronization adjustment information indicated in the second control information (4104) may be applied to the TA and Doppler shift values ​​determined when transmitting the first uplink signal (4112). In the case of the second uplink signal (4114), it may be possible to apply the TA and Doppler shift values ​​determined when transmitting the second uplink signal (4114) by considering both the time and frequency synchronization adjustment information provided in the first control information (4102) and the second control information (4104).

[0531] [Example 11]

[0532] The above-described embodiments describe the processes for synchronizing time and frequency from the perspective of a satellite receiver when a terminal without GNSS functionality transmits on the uplink. The above-described methods may be applicable only to satellite networks. That is, a terminal may be able to apply different TA adjustment mechanisms depending on whether the network it is connected to is a satellite network or a terrestrial network.

[0533] Figure 42 is a flowchart illustrating a procedure for adjusting TA depending on whether the network to which a terminal is connected is a satellite network or a terrestrial network, according to one embodiment of the present disclosure. The operations of Figure 42 may be applied only to terminals that do not have GNSS capabilities, or may be applied regardless of such capabilities.

[0534] Referring to FIG. 42, in operation 4202, the terminal can distinguish whether the connected network is a satellite network or a terrestrial network based on the SIB information received through the initial connection process. For example, if a satellite network-only SIB is received, it may be possible to determine that the terminal's connected network is a satellite network. Conversely, if a satellite network-only SIB is not received, it may be possible to determine that the terminal's connected network is a terrestrial network. In one embodiment, the terminal can determine whether the network transmitting the SS / PBCH is a terrestrial network or a satellite network through a separate field included in the MIB or SIB1. In the present disclosure, a terrestrial network refers to an environment in which a terminal and a base station communicate without a separate artificial satellite, and a satellite network refers to an environment in which a terminal and a base station (or ground station) communicate via an artificial satellite.

[0535] If the terminal determines the satellite network, the terminal may be able to transmit an uplink signal based on the first TA adjustment method in operation 4204. For example, the first TA adjustment method refers to a method of determining a TA by considering at least one of a TA value determined by a frequency band and a duplexing mode, a TA value determined by considering a delay time between a satellite and a ground station, and TA values ​​indicated by a separate upper signal and an L1 signal. Here, the separate upper signal and the L1 signal refer to the methods described in the sixth to ninth embodiments. As another example, the first TA adjustment method refers to a method of determining a TA by considering at least one of a TA value determined by a frequency band and a duplexing mode, a TA value determined by considering a delay time between a satellite and a ground station, a TA value determined through a MAC CE, and, if the terminal has a GNSS, a TA value calculated by the terminal by considering its own location information and satellite location information.

[0536] If the terminal determines to be a terrestrial network, the terminal may be able to transmit an uplink signal based on a second TA adjustment method in operation 4206. The second TA adjustment method refers to a method for determining a TA by considering at least one of a TA value determined by a frequency band and a duplexing mode and a TA value determined through a MAC CE.

[0537] [Example 12]

[0538] When a terminal is connected to a satellite network, it may be possible to apply different TA adjustment mechanisms depending on whether or not the terminal connected to the satellite network supports the GNSS function.

[0539] FIG. 43 is a flowchart showing a procedure for adjusting TA according to a terminal capability report transmitted by a terminal according to one embodiment of the present disclosure.

[0540] Referring to FIG. 43, in operation 4302, the terminal transmits to the base station via a terminal capability report whether it supports GNSS functions after performing an initial connection. A satellite or base station may support different TA adjustment mechanisms depending on whether or not a terminal connected to its network supports GNSS functions.

[0541] If the terminal supports the GNSS function and reports it to the base station, the terminal may be able to transmit and receive an uplink signal based on the third TA adjustment method in operation 4304. The third TA adjustment method refers to a method of determining a TA by considering at least one of a TA value determined by a frequency band and a duplexing mode, a TA value determined by considering a delay time between a satellite and a ground station, a TA value determined through MAC CE, and a TA value calculated by the terminal itself by considering its own location information determined by the terminal through GNSS and location information of a satellite received through a separate upper signal.

[0542] If the terminal does not support the GNSS function and reports this to the base station, the terminal may be able to transmit and receive an uplink signal based on the fourth TA adjustment method in operation 4306. The fourth TA adjustment method refers to a method of determining a TA by considering at least one of a TA value determined by a frequency band and a duplexing mode, a TA value determined by considering a delay time between a satellite and a ground station, and TA values ​​indicated by a separate upper signal and an L1 signal. Here, the separate upper signal and the L1 signal refer to the methods described in the sixth to ninth embodiments.

[0543] As another example, if a terminal does not report GNSS-related terminal capabilities, it may be possible to always consider the terminal as supporting GNSS functions or as not supporting GNSS functions.

[0544] For convenience of explanation, the first through twelfth embodiments of the present disclosure have been described separately above. However, since each embodiment includes interrelated operations, it is also possible to combine at least two or more embodiments. Furthermore, the methods of each embodiment are not mutually exclusive, and it is also possible to perform a combination of one or more methods.

[0545] A base station, a satellite, and a terminal or a transmission and reception method for performing embodiments of the present disclosure are disclosed, and to perform the same, a reception unit, a processing unit, and a transmission unit of the base station, the satellite, and the terminal must each operate according to the embodiments.

[0546] FIG. 44 is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present disclosure.

[0547] Referring to FIG. 44, a terminal (4400) may include a terminal receiving unit (UE receiver) (4430), a terminal transmitting unit (UE transmitter) (4420), and a terminal processing unit (UE processor) (4410). The terminal receiving unit (4430) and the terminal transmitting unit (4420) may be collectively referred to as a transceiver unit in embodiments of the present disclosure.

[0548] The transceiver (4430, 4420) can transmit and receive signals with the base station. The signals can include control information and data. To this end, the transceiver (4430, 4420) can be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts the frequency of a received signal. In addition, the transceiver (4430, 4420) can receive a signal through a wireless channel and output it to the terminal processing unit (4410), and transmit the signal output from the terminal processing unit (4410) through the wireless channel.

[0549] The terminal processing unit (4410) may control a series of processes so that the terminal (4400) can operate according to at least one of the embodiments of the present disclosure described above. For example, the terminal receiving unit (4430) may receive signals from satellite or terrestrial base stations and signals from GNSS, and the terminal processing unit (4410) may transmit and receive signals to and from the base stations according to the method described in the present disclosure. Thereafter, the terminal transmitting unit (4420) may transmit signals using the determined time point.

[0550] FIG. 45 is a block diagram illustrating the internal structure of a satellite according to one embodiment of the present disclosure.

[0551] Referring to FIG. 45, a satellite (4500) may include a satellite receiver (4530), a satellite transmitter (4520), and a satellite processor (4510). The satellite receiver (4530), the satellite transmitter (4520), and the phase processor (4510) may be composed of one or more components. For example, the satellite transmitter (4520) and the satellite receiver (4530) may be composed of a receiver and a transmitter for transmitting and receiving signals from a terminal, a receiver and a transmitter for transmitting and receiving signals from a base station, and / or a receiver and a transmitter for transmitting and receiving signals with another satellite. The satellite receiver (4530) and the satellite transmitter (4520) may be collectively referred to as a satellite transceiver in embodiments of the present disclosure.

[0552] The transceiver (4530, 4520) can transmit and receive signals with the terminal and the base station. The signals can include control information and data. To this end, the transceiver (4530, 4520) can be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts the frequency of a received signal. The transceiver can receive a signal through a wireless channel and output it to the satellite processing unit (4510), and transmit the signal output from the satellite processing unit (4510) through the wireless channel.

[0553] The satellite processing unit (4510) may include a compensator (pre-compensator) for correcting a frequency offset or Doppler shift, and may include a device for tracking a location using GPS, etc. The satellite processing unit (4510) may include a frequency shift function for shifting the center frequency of a received signal. The satellite processing unit (4510) may control a series of processes so that a satellite, a base station, and a terminal can operate according to the above-described embodiment of the present disclosure. For example, the satellite receiving unit (4530) may receive a PRACH preamble from a terminal, transmit a corresponding RAR back to the terminal, and determine to transmit TA information to the base station. Thereafter, the satellite transmitting unit (4520) may transmit the corresponding signals at the determined time.

[0554] FIG. 46 is a block diagram illustrating the internal structure of a base station according to an embodiment of the present disclosure.

[0555] Referring to FIG. 46, a base station (4600) may include a base station reception unit (4630), a base station transmission unit (4620), and a base station processing unit (4610). The base station (4600) may be a terrestrial base station or a part of a satellite. The base station reception unit (4630) and the base station transmission unit (4620) may be collectively referred to as a transceiver in embodiments of the present disclosure. The transceiver units (4630, 4620) may transmit and receive signals with a terminal (e.g., terminal (4400)). The signals may include control information and data. To this end, the transceiver units (4630, 4620) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts the frequency of a received signal. The transceiver unit can receive a signal through a wireless channel and output it to the base station processing unit (4610), and transmit the signal output from the base station processing unit (4610) through the wireless channel.

[0556] The base station processing unit (4610) can control a series of processes so that the base station (4600) can operate according to the above-described embodiment of the present disclosure. For example, the base station processing unit (4610) can transmit an RAR including TA information.

[0557] According to embodiments of the present disclosure, a terminal can connect to a base station via a satellite, and the base station can indicate a time offset to the terminal, and the terminal can calculate and correct the time offset, thereby enabling effective exchange of signals between the base station and the terminal.

[0558] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are merely specific examples to easily explain the technical content of the present disclosure and to help understand the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, each of the above embodiments can be combined and operated as needed. In addition, other modifications based on the technical idea of ​​the above embodiments can be implemented in LTE systems, 5G systems, etc.

Claims

In a method by a terminal (user equipment, UE) in a satellite communication system, An action to perform an initial connection based on the first TA (timing advance) value; After the initial connection, an operation of receiving TA adjustment information and uplink scheduling information related to the update of the first TA value from a satellite or base station; An operation of determining a second TA value based on the above TA adjustment information; and A method characterized by including an operation of transmitting an uplink signal based on the second TA value and the uplink scheduling information. In the first paragraph, Further comprising an operation of receiving first upper signaling information including at least one of reference position information or reference time information related to the satellite from the satellite or base station; A method characterized in that the first TA value is determined by applying at least one of the reference location information or the reference time information. In the first paragraph, the TA adjustment information is: A method characterized in that the terminal associated with the beam corresponding to the satellite includes a Doppler shift value to be applied. In the second paragraph, the reference time information indicates the delay time between the reference position, which is the center of the beam area corresponding to the satellite, and the satellite, and A method characterized in that the above reference time information includes at least one coefficient and at least one constant related to a function that uses time as a variable, and the function represents a delay time between a reference position that is the center of a beam area corresponding to the satellite and the satellite. In the first paragraph, the TA adjustment information and the uplink scheduling information are transmitted in downlink control information (DCI), A method characterized in that the above DCI is a horse-specific DCI or a group-common DCI. In paragraph 5, A method further comprising an operation of receiving second upper signaling information indicating a format of the TA adjustment field of the DCI before receiving the TA adjustment information and the uplink scheduling information after the initial connection. In a method performed by a base station in a satellite communication system, An operation of performing an initial connection with a terminal (user equipment, UE) based on a first TA (timing advance) value; After the initial connection, an operation of transmitting TA adjustment information and uplink scheduling information related to the update of the first TA value to the terminal; A method characterized by including an operation of receiving an uplink signal based on a second TA value based on the TA adjustment information and the uplink scheduling information. In paragraph 7, Further comprising an operation of transmitting first upper signaling information including at least one of reference position information or reference time information related to a satellite to the terminal; A method characterized in that the first TA value is determined by applying at least one of the reference location information or the reference time information. In the 7th paragraph, the TA adjustment information is: A method characterized in that the terminal associated with the beam corresponding to the satellite includes a Doppler shift value to be applied. In the 8th paragraph, the reference time information indicates the delay time between the reference position, which is the center of the beam area corresponding to the satellite, and the satellite, and A method characterized in that the above reference time information includes at least one coefficient and at least one constant related to a function that uses time as a variable, and the function represents a delay time between a reference position that is the center of a beam area corresponding to the satellite and the satellite. In paragraph 7, the TA adjustment information and the uplink scheduling information are transmitted in downlink control information (DCI), A method characterized in that the above DCI is a horse-specific DCI or a group-common DCI. In Article 11, A method further comprising an operation of receiving second upper signaling information indicating a format of the TA adjustment field of the DCI before receiving the TA adjustment information and the uplink scheduling information after the initial connection. In a terminal (user equipment, UE) performing uplink transmission in a satellite communication system, Transmitter and receiver; and At least one processor connected to the transceiver, wherein the at least one processor comprises: Perform initial connection based on the first TA (timing advance) value, After the initial connection, TA adjustment information and uplink scheduling information related to the update of the first TA value are received from a satellite or base station, Determine the second TA value based on the above TA adjustment information, and A terminal configured to perform uplink transmission based on the second TA value and the uplink scheduling information. In the 13th paragraph, the at least one processor, configured to receive first upper signaling information including at least one of reference position information or reference time information related to a satellite, and A terminal characterized in that the first TA value is determined by applying at least one of the reference location information or the reference time information. In a satellite communication system, at a base station, Transmitter and receiver; and At least one processor; comprising: Performs initial connection with the terminal (user equipment, UE) based on the first TA (timing advance) value, After the initial connection, TA adjustment information and uplink scheduling information related to the update of the first TA value are transmitted to the terminal, and A base station characterized by including an operation of receiving an uplink signal based on a second TA value based on the TA adjustment information and the uplink scheduling information.

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