Method and apparatus for indicating timing advance in a communication system

Abstract

The present invention provides a communication technique and system for integrating a 5G communication system, which supports a higher data transfer rate after the 4G system, with IoT technology. [Solution] The present invention is based on 5G communication technology and IoT related technology and is applied to intelligent services (such as smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail, security and safety related services, etc.). The present invention discloses a method and device for a terminal to perform satellite communication.

Description

[Technical Field]

[0001] The present invention relates to a communication system, and more particularly to a method and apparatus for correcting a time offset when a terminal transmits and receives signals to a base station via a satellite, in which time offset correction is required depending on the distance between the terminal and the satellite. The present invention relates to a method and apparatus for correcting a time offset when a base station indicates time offset information to a terminal and the terminal uses the indicated information. [Background technology]

[0002] Since the commercialization of 4G communication systems, efforts have been made to develop improved 5G or pre-5G communication systems to meet the ever-increasing demand for wireless data traffic. For this reason, 5G or pre-5G communication systems are also referred to as beyond-4G or post-LTE systems. To achieve high data rates, 5G communication systems are being considered for implementation in ultra-high frequency (mmWave) bands (e.g., the 60 GHz band). To mitigate radio wave path loss and increase radio wave propagation distance in ultra-high frequency bands, technologies such as beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antennas are being discussed for 5G communication systems. In addition, to improve the system's network, technologies being developed for 5G communication systems include advanced small cells, improved small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, moving networks, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation.Other advanced coding modulation (ACM) methods being developed for 5G systems include FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), as well as advanced connection technologies such as FBMC (Filter Bank Multi Carrier), NOMA (non-orthogonal multiple access), and SCMA (sparse code multiple access).

[0003] Meanwhile, the Internet is evolving from a human-centered network where humans generate and consume information to the Internet of Things (IoT), a network where information is exchanged and processed among distributed components such as objects. IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology using connections to cloud servers, is also emerging. To realize IoT, technological elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required. Recently, research has focused on sensor networks for connecting objects, machine-to-machine (M2M) communication, and machine-type communication (MTC). The IoT environment provides intelligent IT (Internet Technology) services that collect and analyze data generated by connected objects to create new value in people's lives. The IoT is being applied to areas such as smart homes, smart buildings, smart cities, smart cars (connected cars), smart grids, healthcare, smart home appliances, and advanced medical services through the integration and fusion of existing IT (information technology) and various industries.

[0004] Therefore, various attempts are being made to apply 5G communication systems to IoT networks. For example, 5G communication technologies such as sensor networks, machine-to-machine (M2M) communication, and MTC (machine-type communication) are being realized using techniques such as beamforming, MIMO, and array antennas. The application of cloud radio access networks (cloud RAN) as the big data processing technology mentioned above is also an example of the fusion of 5G and IoT technologies.

[0005] Meanwhile, as satellite launch costs dramatically decreased in the late 2010s and into the 2020s, more companies are looking to provide communication services via satellite. As a result, satellite networks have emerged as a next-generation network system that complements existing terrestrial networks. While they cannot provide the same user experience as terrestrial networks, their advantage is that they can provide communication services in areas where it is difficult to build terrestrial networks or in disaster situations. As mentioned above, the recent sharp decline in satellite launch costs has made them economically viable. Additionally, some companies and the 3GPP (registered trademark) standardization organization are also promoting direct communication between smartphones and satellites.

[0006] When a terminal attempts to connect to a base station via a satellite, there is a long distance of hundreds or thousands of kilometers between the terminal and the satellite, and between the satellite and the terrestrial base station, resulting in a large delay time when the radio waves arrive. This large delay time is much larger than when the terminal communicates directly with the base station via a terrestrial network. Furthermore, this delay time changes over time as the satellite moves continuously. The delay time between the satellite and the base station changes for all terminals. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above-mentioned conventional problems, and an object of the present invention is to provide a method and apparatus in which, when a terminal transmits and receives signals to and from a base station via a satellite in a communication system, the base station indicates a time offset to correct for varying delay times caused by the long distance to the satellite and the movement of the satellite, and the terminal performs the correction based on the time offset. [Means for solving the problem]

[0008] In order to achieve the above object, according to one aspect of the present invention, a method performed by a base station in a communication system includes the steps of transmitting information indicating a delay variation rate to a terminal, and receiving an uplink signal transmitted from the terminal based on the delay variation rate, wherein the information indicating the delay variation rate is transmitted by higher layer signaling or L1 control information.

[0009] The method may further include transmitting, to the terminal, information regarding at least one of a time point or a period at which the delay variation rate is applied. The method further includes transmitting information regarding a TA (timing advance) value to the terminal via a system information block, and the information regarding the TA value may include at least one of first TA information common to a terminal group and second TA information indicated to a specific terminal. The method may further include transmitting one or more TA loop setting information to the terminal, and transmitting information on a TA value and a TA loop index to the terminal.

[0010] In order to achieve the above object, according to one aspect of the present invention, a method performed by a terminal in a communication system includes the steps of receiving information indicating a delay variation rate from a base station, confirming a delay to be applied based on the information indicating the delay variation rate, and transmitting an uplink signal to the base station by applying the confirmed delay, wherein the information indicating the delay variation rate is transmitted by higher layer signaling or L1 control information.

[0011] In order to achieve the above object, according to one aspect of the present invention, a base station in a communication system includes a transceiver unit and a controller connected to the transceiver unit, wherein the controller transmits information indicating a delay variation rate to a terminal and controls the terminal to receive an uplink signal transmitted by the terminal based on the delay variation rate, and the information indicating the delay variation rate is transmitted by higher layer signaling or L1 control information.

[0012] In order to achieve the above object, according to one aspect of the present invention, a terminal in a communication system includes a transceiver unit and a controller connected to the transceiver unit, wherein the controller receives information indicating a delay variation rate from a base station, confirms a delay to be applied based on the information indicating the delay variation rate, and controls the base station to apply the confirmed delay to transmit an uplink signal, and the information indicating the delay variation rate is transmitted by higher layer signaling or L1 control information. [Effects of the Invention]

[0013] According to the present invention, when a terminal connects to a base station via a satellite, the base station instructs the terminal about a time offset, and the terminal corrects the time offset, thereby enabling effective signal exchange between the base station and the terminal. [Brief explanation of the drawings]

[0014] [Figure 1]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 on the downlink or uplink in an NR system. [Figure 2] FIG. 1 is a diagram illustrating an example of a control region in which a downlink control channel is transmitted in a 5G wireless communication system. [Figure 3] FIG. 10 is a diagram showing an example in which eMBB, URLLC, and mMTC data are allocated to the frequency band of the entire system. [Figure 4] FIG. 10 is a diagram showing an example in which the frequency band of the system is divided and eMBB, URLLC, and mMTC data are allocated. [Figure 5] 10 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. [Figure 6] This figure shows how the synchronization signal (SS) and physical broadcast channel (PBCH) of an NR system are mapped in the frequency and time domains. [Figure 7] FIG. 10 is a diagram illustrating symbols that can be used to transmit an SS / PBCH block depending on the subcarrier spacing. [Figure 8] FIG. 10 is a diagram illustrating the processing time of a terminal due to timing advance when the terminal receives a first signal and transmits a second signal in response to the first signal in a 5G or NR system according to one embodiment of the present invention. [Figure 9] 1 illustrates 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. [Figure 10] FIG. 1 is a diagram illustrating an example of a communication system using a satellite. [Figure 11] FIG. 1 illustrates the orbital period of a communications satellite relative to the Earth as a function of the satellite's altitude or height. [Figure 12] FIG. 1 illustrates the concept of satellite-terminal direct communication. [Figure 13] FIG. 1 illustrates a scenario for utilizing satellite-terminal direct communication. [Figure 14]FIG. 1 is a diagram showing an example of calculation of expected data transfer rate (throughput) in the uplink when a LEO satellite at an altitude of 1200 km communicates directly with a terminal on the ground. [Figure 15] FIG. 1 is a diagram showing an example of calculation of expected data throughput in the uplink when a GEO satellite at an altitude of 35,786 km communicates directly with a terminal on the ground. [Figure 16] 10 is a diagram showing path loss values ​​according to a path loss model between a terminal and a satellite, and path loss according to a path loss model between a terminal and a terrestrial network communication base station. FIG. [Figure 17] 1 is a diagram showing a formula and results for calculating the amount of Doppler shift a signal undergoes when received by a terrestrial user transmitted from a satellite, depending on the altitude and position of the satellite and the position of the terrestrial user. [Figure 18] FIG. 1 illustrates the velocity of a satellite calculated at the altitude of the satellite. [Figure 19] FIG. 2 illustrates the Doppler shift experienced by an individual terminal located within one beam transmitted by a satellite to the ground. [Figure 20] FIG. 10 is a diagram showing the difference in Doppler shift that occurs within one beam depending on the position of the satellite determined from the altitude angle. [Figure 21] 1 is a diagram showing the delay time from a terminal to a satellite and the round-trip delay time between the terminal, satellite, and base station depending on the satellite's position determined by the altitude angle. [Figure 22] FIG. 10 is a diagram showing the maximum difference in round trip delay time depending on the user's position within a single beam. [Figure 23] FIG. 1 is a diagram illustrating an example of the information structure of a RAR. [Figure 24] FIG. 10 is a diagram illustrating an example of the relationship between PRACH preamble configuration resources and RAR reception times in an LTE system. [Figure 25] A diagram showing an example of the relationship between PRACH preamble configuration resources and RAR reception times in a 5GNR system. [Figure 26]FIG. 10 is a diagram illustrating an example of downlink frame and uplink frame timing in a terminal. [Figure 27A] 1 illustrates an example of the continuous motion of a satellite on the Earth's surface or at a terminal located on the Earth as the satellite revolves around the Earth along a satellite orbit; [Figure 27B] FIG. 1 is a diagram illustrating an example of the structure of an artificial satellite. [Figure 28] FIG. 1 is a diagram illustrating an example of the difference in propagation delay time between a terrestrial network and a satellite network. [Figure 29] FIG. 1 illustrates an example of applying timing advance in terrestrial and satellite networks. [Figure 30] FIG. 10 is a diagram showing an example of the maximum difference in round-trip propagation delay time experienced by users between a terminal, a satellite, and a base station when multiple users are located within one beam transmitted by a satellite. [Figure 31A] FIG. 1 is a diagram showing an example of round-trip propagation delay time between a terminal and a base station that changes due to the movement of a satellite along its orbit. [Figure 31B] FIG. 1 is a diagram showing an example in which multiple terminals are located within one beam area provided by one satellite. [Figure 31C] FIG. 10 is a diagram showing an example of instructing a time offset to a group of terminals using one MAC CE. [Figure 32] 10 is a diagram illustrating an example in which the beam or satellite to which a terminal is connected is changed, but the terrestrial base station connected to the terminal is not changed. [Figure 33] This is a diagram showing an example in which the terrestrial base station or ground station connected to the terminal is also changed when the beam or satellite to which the terminal is connected (or receives service) is changed. [Figure 34] FIG. 10 is a diagram showing an example of a TA loop. [Figure 35A] FIG. 10 is a diagram illustrating an example of the operation of a base station for indicating a TA value. [Figure 35B] FIG. 10 is a diagram illustrating an example of the operation of a terminal for indicating a TA value. [Figure 36A] FIG. 10 is a diagram illustrating an example of the operation of a base station that transmits a PUSCH by applying a TA value instruction. [Figure 36B] FIG. 10 is a diagram illustrating an example of the operation of a terminal that transmits a PUSCH by applying a TA value instruction. [Figure 37A] A diagram showing an example of the operation of a base station for reporting a TA value of a terminal. [Figure 37B] FIG. 10 is a diagram illustrating an example of the operation of a terminal for reporting a TA value of the terminal. [Figure 38] 2 is a block diagram showing the internal structure of a terminal according to an embodiment of the present invention; [Figure 39] 1 is a block diagram illustrating the internal structure of a satellite according to an embodiment of the present invention. [Figure 40] 2 is a block diagram showing the internal structure of a base station according to one embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0015] The new 5G communication, New Radio Access Technology (NR), is designed to allow various services to be freely multiplexed in time and frequency resources, allowing waveforms / numerologies and reference signals to be dynamically or freely allocated according to the needs of the respective services. To provide optimal services to terminals in wireless communication, optimized data transmission using channel quality and interference measurement is essential, making accurate channel state measurement essential. However, unlike 4G communication, in which channel and interference characteristics do not vary significantly depending on frequency resources, 5G channels vary significantly depending on the service. Therefore, frequency resource group (FRG)-based subsets are required to enable separate measurements. Meanwhile, in the NR system, supported services are categorized into categories such as enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable and low-latency communications (URLLC). eMBB is a service that aims to transmit large amounts of data at high speeds, mMTC is a service that aims to minimize terminal power consumption and connect multiple terminals, and URLLC is a service that aims to provide high reliability and low latency. Different requirements apply depending on the type of service applied to the terminal.

[0016] In this way, multiple services are provided to users in a communication system, and in order to provide such multiple services to users, a method and an apparatus using the same that provide each service within the same time interval according to its characteristics are required.

[0017] Hereinafter, specific examples of embodiments of the present invention will be described in detail with reference to the drawings.

[0018] In the description of the embodiments, technical details that are well known in the technical field to which the present invention pertains and that are not directly related to the present invention will be omitted in order to more clearly convey the gist of the present invention without obscuring it.

[0019] For the same reason, some components in the drawings are exaggerated, omitted, or shown in outline, and the size of each component does not directly reflect the actual size. In the drawings, the same or corresponding components are designated by the same reference numerals.

[0020] The advantages and features of the present invention, as well as methods for achieving them, will become clear from the following detailed description of the embodiments together with the drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various other forms. The present embodiments are provided solely to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains, and the present invention is defined by the scope of the claims. The same reference symbols refer to the same elements throughout the specification.

[0021] It will be understood that each block of the process flowchart and combinations of the flowcharts are implemented by computer program instructions. These computer program instructions are embodied in a processor of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that the instructions, when executed by the processor of the computer or other programmable data processing device, create means for performing the functions described in the flowchart blocks. These computer program instructions are stored in a computer-usable or computer-readable memory that directs the computer or other programmable data processing device to implement the functions in a particular way, such that the instructions stored in the computer-usable or computer-readable memory can produce an article of manufacture that embodies instruction means for performing the functions described in the flowchart blocks. The computer program instructions are embodied in a computer or other programmable data processing device, such that the computer or other programmable data processing device performs a series of operation steps, and the instructions that create a computer-implemented process to run the computer or other programmable data processing device provide the steps for performing the functions described in the flowchart blocks.

[0022] Each block represents a module, segment, or portion of code that includes one or more executable instructions for performing a specified logical function. Note that in some alternative implementations, the functions described in the blocks may occur out of order. For example, two blocks shown in succession may be performed substantially simultaneously, or the blocks may sometimes be performed in reverse order depending on the function in question.

[0023] The term "module" used in this embodiment refers to software or hardware components such as FPGAs or ASICs, and the "module" performs a certain function. However, the "module" is not limited to software or hardware. The "module" may be configured to reside on an addressable storage medium or to implement one or more processors. Thus, for example, the "module" includes components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The components and functions provided within the "modules" may be combined into fewer components and "modules" or further separated into additional components and "modules." Furthermore, the components and "modules" may be embodied to implement one or more CPUs within a device or a security multimedia card. In addition, in this embodiment, the "module" includes one or more processors.

[0024] Wireless communication systems have evolved beyond providing voice-centric services in the early days to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards such as 3GPP's high speed packet access (HSPA), long term evolution (LTE, or evolved universal terrestrial radio access (E-UTRA)), LTE-Advanced (LTE-A), 3GPP2's high rate packet data (HRPD), ultra mobile broadband (UMB), and IEEE 802.16e. In addition, communication standards such as 5G or new radio (NR) are being developed as fifth-generation wireless communication systems.

[0025] As a representative example of a broadband wireless communication system, the NR system employs orthogonal frequency division multiplexing (OFDM) in the downlink (DL) and uplink. More specifically, the downlink employs cyclic-prefix OFDM (CP-OFDM), and the uplink employs both CP-OFDM and discrete Fourier transform spreading OFDM (DFT-S-OFDM). The uplink refers to a radio link through which a terminal (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 radio link through which a base station transmits data or control signals to the terminal. Such multiple access schemes typically allocate and operate time-frequency resources carrying data or control information for each user so that they do not overlap, i.e., so that orthogonality is established, thereby separating the data or control information of each user.

[0026] The NR system employs a hybrid automatic repeat request (HARQ) method that retransmits data at the physical layer if a decoding failure occurs during the initial transmission. In the HARQ method, if the receiver is unable to correctly decode data, it sends a negative acknowledgment (NACK) to the transmitter to notify the transmitter of the decoding failure, allowing the transmitter to retransmit the data at the physical layer. The receiver improves data reception performance by combining the retransmitted data with the previously unsuccessfully decoded data. Furthermore, if the receiver correctly decodes the data, it sends an acknowledgement (ACK) to the transmitter to notify the transmitter of successful decoding, allowing the transmitter to transmit new data.

[0027] 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 on the downlink or uplink in an NR system.

[0028] In Figure 1, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. In the time domain, the minimum transmission unit is an OFDM symbol, and Nsymb OFDM symbols 102 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. In the frequency domain, the minimum transmission unit is a subcarrier, and the bandwidth of the transmission bandwidth of the entire system is made up of a total of NBW subcarriers 104. One frame is defined as 10 ms. One subframe is defined as 1 ms, and therefore one frame consists of a total of 10 subframes. One slot is defined as 14 OFDM symbols (i.e., the number of symbols per slot is TIFF0007768970000001.tif121281 A subframe consists of one or more slots, and the number of slots per subframe varies depending on the set value μ for the subcarrier spacing. In the example of Figure 2, the set values ​​for the subcarrier spacing are shown as μ=0 and μ=1. When μ=0, one subframe consists of one slot, and when μ=1, one subframe consists of two slots. In other words, the number of slots per subframe varies depending on the set value μ for the subcarrier spacing. TIFF0007768970000002.tif12128 is different, which means the number of slots per frame TIFF0007768970000003.tif12128 is different. The spacing between each subcarrier is set by μ. TIFF0007768970000004.tif12128 is defined as shown in Table 1 below.

[0029] [Table 1]

[0030] Before radio resource control (RRC) connection, a terminal receives an initial bandwidth part (initial BWP) for initial connection from the base station via a master information block (MIB). More specifically, the terminal receives configuration information regarding a control region (control resource set: CORESET) and a search space in which a physical downlink control channel (PDCCH) for receiving system information (which may correspond to remaining system information (RMSI) or system information block 1 (SIB1)) required for initial connection is transmitted during the initial connection phase via the MIB. The control region and search space configured via the MIB are each regarded as an identity (ID) 0. The base station notifies the terminal of configuration information such as frequency allocation information, time allocation information, and numerology for control region #0 via the MIB. The base station also notifies the terminal of configuration information regarding a monitoring period and occasion for control region #0, i.e., configuration information for search space #0, via the MIB. The terminal regards the frequency domain set as control domain #0 obtained from the MIB as the initial bandwidth portion for the initial connection. At this time, the identifier (ID) of the initial bandwidth portion is regarded as 0.

[0031] The MIB contains the following information:

[0032] TIFF0007768970000006.tif248167

[0033] In the method for configuring the bandwidth portion, a terminal before RRC connection receives configuration information for the initial bandwidth portion using an MIB during an initial connection stage. More specifically, a control region for a downlink control channel (DCI) capable of transmitting downlink control information (DCI) for scheduling an SIB is configured in the terminal according to the MIB of a physical broadcast channel (PBCH). At this time, the bandwidth of the control region configured by the MIB is considered the initial bandwidth portion, and the terminal receives a physical downlink shared channel (PDSCH) through which the SIB is transmitted in the configured initial bandwidth portion. In addition to receiving the SIB, the initial bandwidth portion is also used for other system information (OSI), paging, and random access.

[0034] If one or more bandwidth parts are configured for the terminal, the base station instructs the terminal to change the bandwidth part using a bandwidth part indicator field in the DCI.

[0035] In the time-frequency domain, the basic unit of a resource is a resource element (RE) 112, which is indicated by an OFDM symbol index and a subcarrier index. A resource block (RB (resource block) or PRB (physical resource block)) 108 is defined as NRB consecutive subcarriers 110 in the frequency domain. Generally, the minimum data transmission unit is an RB unit. In an NR system, Nsymb=14 and NRB=12, and NBW is proportional to the bandwidth of the system transmission band. The data rate increases in proportion to the number of RBs scheduled to a terminal.

[0036] In an NR system, in the case of an FDD system in which the downlink and uplink are operated by separating the frequency, the downlink transmission bandwidth and the uplink transmission bandwidth are different from each other. The channel bandwidth represents the RF bandwidth corresponding to the system transmission bandwidth. Tables 2 and 3 show some of the correspondences between the system transmission bandwidth, subcarrier spacing, and channel bandwidth defined for NR systems in frequency bands lower than 6 GHz and higher than 6 GHz, respectively. For example, an NR system with a subcarrier spacing of 30 kHz and a 100 MHz channel bandwidth has a transmission bandwidth consisting of 273 RBs. In the following, N / A indicates a bandwidth-subcarrier combination not supported by the NR system.

[0037] FR1 (Frequency Range 1) Configuration

[0038] [Table 2]

[0039] FR2 (Frequency Range 2) Configuration

[0040] [Table 3]

[0041] In an NR system, the frequency range is defined as being divided into FR1 and FR2 as shown in Table 4 below.

[0042] [Table 4]

[0043] The ranges of FR1 and FR2 are changed and applied as above. For example, the frequency range of FR1 is changed and applied to 450 MHz to 6000 MHz.

[0044] Next, we will explain the SS (synchronization signal) / PBCH block in 5G.

[0045] The SS / PBCH block refers to a physical layer channel block consisting of a PSS (primary SS), an SSS (secondary SS), and a PBCH. Specifically, it is as follows:

[0046] PSS: A signal that serves as a reference for downlink time / frequency synchronization and provides some information about the cell ID.

[0047] SSS: It serves as a reference for downlink time / frequency synchronization and provides the remaining cell ID information that PSS does not provide. It also serves as a reference signal for demodulating the PBCH.

[0048] PBCH: Provides essential system information required for transmission and reception of data channels and control channels of a terminal. The essential system information includes search space-related control information indicating radio resource mapping information of a control channel, scheduling control information for a separate data channel that transmits system information, etc.

[0049] SS / PBCH block: The SS / PBCH block is a combination of PSS, SSS, and PBCH. One or more SS / PBCH blocks are transmitted within a 5 ms time period, and each transmitted SS / PBCH block is identified by an index.

[0050] During the initial connection phase, the terminal detects the PSS and SSS and decodes the PBCH. The terminal acquires the MIB from the PBCH, thereby configuring control region #0 (corresponding to the control region with control region index 0). The terminal monitors control region #0, assuming that the demodulation reference signal (DMRS) transmitted in the selected SS / PBCH block and control region #0 is quasi-co-located (QCL). The terminal receives system information as downlink control information transmitted in control region #0. The terminal acquires configuration information related to the random access channel (RACH) required for initial connection from the received system information. The terminal transmits a physical RACH (PRACH) to the base station taking into account the selected SS / PBCH index, and the base station receiving the PRACH acquires information regarding the SS / PBCH block index selected by the terminal. Through this process, the base station knows that the terminal is monitoring the block selected from each SS / PBCH block and its associated control region #0.

[0051] Next, we will explain in detail the downlink control information (DCI) in the 5G system.

[0052] In a 5G system, scheduling information for uplink data (or physical uplink data channel (PUSCH)) or downlink data (or physical downlink shared channel (PDSCH)) is transmitted from a base station to a terminal by DCI. The terminal monitors a fallback DCI format and a non-fallback DCI format for the PUSCH or PDSCH. The fallback DCI format is composed of fixed fields previously defined between the base station and the terminal, and the non-fallback DCI format includes configurable fields. There are various other DCI formats, and each format indicates whether it is a DCI for power control or a DCI for notifying an SFI (slot format indicator), etc.

[0053] DCI is transmitted on a PDCCH, which is a physical downlink control channel, after undergoing channel coding and modulation processes. A cyclic redundancy check (CRC) is added to the payload of the DCI message, and the CRC is scrambled with an RNTI (radio network temporary identifier) ​​corresponding to the identity of the UE. A different RNTI is 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 explicitly transmitted but is included in the CRC calculation process and transmitted. Upon receiving a DCI message transmitted on the PDCCH, the UE checks the CRC using the assigned RNTI. If the CRC check results match, the UE knows that the message was transmitted to the UE. The PDCCH is mapped to a control resource set (CORESET) configured for the UE and transmitted.

[0054] For example, DCI for scheduling a PDSCH for system information (SI) is scrambled with SI-RNTI. DCI for scheduling a PDSCH for a random access response (RAR) message is scrambled with RA-RNTI. DCI for scheduling a PDSCH for a paging message is scrambled with P-RNTI. DCI for reporting a slot format indicator (SFI) is scrambled with SFI-RNTI. DCI for reporting transmit power control (TPC) is scrambled with TPC-RNTI. DCI for scheduling a terminal-specific PDSCH or PUSCH is scrambled with C-RNTI (Cell RNTI).

[0055] DCI format 0_0 is used as a fallback DCI for scheduling PUSCH, and in this case, the CRC is scrambled with the C-RNTI. DCI format 0_0 with the CRC scrambled with the C-RNTI includes, for example, the following information:

[0056] [Table 5]

[0057] DCI format 0_1 ​​is used as a non-fallback DCI for scheduling PUSCH, and in this case, the CRC is scrambled with the C-RNTI. DCI format 0_1 ​​with the CRC scrambled with the C-RNTI includes, for example, the following information:

[0058] [Table 6] TIFF0007768970000012.tif246166

[0059] DCI format 1_0 is used as a fallback DCI for scheduling a PDSCH, and in this case, the CRC is scrambled with the C-RNTI. DCI format 1_0 with the CRC scrambled with the C-RNTI includes, for example, the following information:

[0060] [Table 7]

[0061] DCI format 1_1 is used as a non-fallback DCI for scheduling a PDSCH, and in this case, the CRC is scrambled with the C-RNTI. DCI format 1_1 in which the CRC is scrambled with the C-RNTI includes, for example, the following information:

[0062] [Table 8]

[0063] The following describes a time domain resource allocation method for data channels in a 5G communication system.

[0064] The base station configures a table for time domain resource allocation information for a downlink data channel (PDSCH) and an uplink data channel (PUSCH) in the terminal through higher layer signaling (e.g., RRC signaling). For the PDSCH, the base station configures a table consisting of a maximum of maxNrofDL-Allocations=16 entries, and for the PUSCH, the base station configures a table consisting of a maximum of maxNrofUL-Allocations=16 entries. The time domain resource allocation information includes, for example, PDCCH-to-PDSCH slot timing (corresponding to the time interval in slot units between the time when the PDCCH is received and the time when the PDSCH scheduled by the received PDCCH is transmitted, denoted by K0) or PDCCH-to-PUSCH slot timing (corresponding to the time interval in slot units between the time when the PDCCH is received and the time when the PUSCH scheduled by the received PDCCH is transmitted, denoted by K2), information on the position and length of the start symbol where the PDSCH or PUSCH is scheduled within the slot, a mapping type of the PDSCH or PUSCH, etc. For example, information such as those shown in Tables 9 and 10 below is notified from the base station to the terminal.

[0065] [Table 9]

[0066] [Table 10]

[0067] The base station notifies the terminal of one of the table entries for time domain resource allocation information by L1 signaling (e.g., DCI) (e.g., by indicating it in a "time domain resource allocation" field in the DCI). The terminal obtains time domain resource allocation information for the PDSCH or PUSCH based on the DCI received from the base station.

[0068] Below, the downlink control channel in the 5G communication system will be described in more detail with reference to the drawings.

[0069] FIG. 2 is a diagram showing an example of a control region in which a downlink control channel is transmitted in a 5G wireless communication system. FIG. 2 shows an example in which a UE bandwidth part 210 is set on the frequency axis, and two control regions (control region #1 201 and control region #2 202) are set within one slot 220 on the time axis. In the control regions (201, 202), specific frequency resources 203 in the entire UE bandwidth part 210 are set on the frequency axis. One or more OFDM symbols are set on the time axis, and this is defined as a control region length (Control Resource Set Duration) 204. Referring to the example shown in FIG. 2, control region #1 201 is set as a control region length of two symbols, and control region #2 202 is set as a control region length of one symbol.

[0070] The above-mentioned control region in 5G is configured by the base station to the terminal through higher layer signaling (e.g., system information, MIB, RRC signaling). Configuring the control region in the terminal means providing information such as the control region identifier, the frequency location of the control region, and the symbol length of the control region. For example, the higher layer signaling includes the information in Table 11 below.

[0071] [Table 11]

[0072] In Table 11, the tci-StatesPDCCH (simply referred to as TCI (transmission configuration indication) state) configuration information includes information on one or more SS / PBCH block indexes or CSI-RS (channel state information reference signal) indexes that have a QCL relationship with the DMRS transmitted in the corresponding control region. As an example, each control information included in DCI format 1_1, which is scheduling control information (DL grant) for downlink data, is as follows:

[0073] Carrier indicator: indicates on which carrier the data scheduled by the DCI is transmitted. 0 or 3 bits

[0074] Identifier for DCI formats: An indicator that indicates the DCI format, specifically, whether the DCI is for downlink or uplink. [1] bit

[0075] Bandwidth part indicator: Indicates if there is a change in the bandwidth part. 0, 1, or 2 bits

[0076] Frequency domain resource assignment: Resource assignment information indicating frequency domain resource assignment, and the resources represented differ depending on whether the resource assignment type is 0 or 1.

[0077] Time domain resource assignment: Resource assignment information indicating time domain resource assignment, which indicates higher layer signaling or a predefined PDSCH time domain resource assignment list. 1, 2, 3, or 4 bits

[0078] VRB-to-PRB mapping: 0 or 1 bit indicating the mapping relationship between virtual resource blocks (VRBs) and physical resource blocks (PRBs).

[0079] PRB bundling size indicator: 0 or 1 bit indicating the physical resource block bundling size to which the same precoding is assumed to be applied.

[0080] Rate matching indicator: 0, 1 or 2 bits indicating which rate match group is applied among the rate match groups configured by higher layers to be applied to the PDSCH.

[0081] - ZP CSI-RS trigger: Triggers the zero power channel state information reference signal. - 0, 1 or 2 bits

[0082] Transport block (TB) related setting information: indicates the MCS (Modulation and coding scheme), NDI (New data indicator), and RV (Redundancy version) for one or two TBs.

[0083] Modulation and coding scheme (MCS): Indicates the modulation scheme and coding rate used for data transmission, i.e., whether QPSK, 16QAM, 64QAM, or 256QAM, as well as the coding rate value indicating TBS and channel coding information.

[0084] New data indicator: Indicates whether it is an initial transmission or a retransmission of HARQ.

[0085] Redundancy version: Indicates the redundancy version of HARQ.

[0086] HARQ process number: 4 bits indicating the HARQ process number applied to the PDSCH.

[0087] Downlink assignment index: An index for generating a dynamic HARQ-ACK codebook when reporting HARQ-ACK for PDSCH. 0, 2, or 4 bits

[0088] TPC command for scheduled PUCCH: Power control information applied to PUCCH for HARQ-ACK reporting for PDSCH. 2 bits

[0089] PUCCH resource indicator: Information indicating the PUCCH resource for HARQ-ACK reporting for PDSCH. 3 bits

[0090] PDSCH-to-HARQ_feedback timing indicator: 3 bits This is setting information on which slot the PUCCH for HARQ-ACK report for PDSCH is transmitted in.

[0091] Antenna ports: 4, 5, or 6 bits indicating the antenna ports of the PDSCH DMRS and the DMRS CDM groups on which the PDSCH is not transmitted

[0092] -Transmission configuration indication: Information indicating PDSCH beam-related information, -0 or 3 bits

[0093] - SRS request: Information requesting SRS transmission - 2 bits

[0094] CBG transmission information: 0, 2, 4, 6, or 8 bits indicating which code block group (CBG) data is transmitted over the PDSCH when code block group-based retransmission is configured

[0095] CBG flushing out information: Information indicating whether a code block group previously received by the terminal is available for HARQ combining. 0 or 1 bit

[0096] DMRS sequence initialization: 1 bit indicating the DMRS sequence initialization parameters.

[0097] In the above data transmission via PDSCH or PUSCH, time domain resource assignment is conveyed by information about a slot in which the 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, where S is a relative position from the start of the slot and L is the number of consecutive symbols, and S and L are determined from start and length indicator values ​​(SLIV) defined as in Equation 1 below.

[0098]

number

[0099] In an NR system, information about an SLIV value, a PDSCH / PUSCH mapping type, and a slot in which the PDSCH / PUSCH is transmitted is configured in one row of a terminal by RRC configuration (for example, information is configured in the form of a table). Then, in the time domain resource allocation of DCI, the base station conveys information about the SLIV value, the PDSCH / PUSCH mapping type, and a slot in which the PDSCH / PUSCH is transmitted to the terminal by indicating an index value in the configured table.

[0100] In the NR system, two PDSCH mapping types, Type A and Type B, are defined. In PDSCH mapping Type A, the first symbol of the DMRS symbol is located in the second or third OFDM symbol of the slot. In PDSCH mapping Type B, the first symbol of the DMRS symbol is located in the first OFDM symbol of the time domain resource allocated by PUSCH transmission.

[0101] Downlink data is transmitted on a PDSCH, a physical channel for downlink data transmission. The PDSCH is transmitted after the transmission period of the control channel, and scheduling information such as a specific mapping position in the frequency domain and a modulation scheme is determined based on the DCI transmitted on the PDCCH.

[0102] Using the MCS among the control information constituting the DCI, the base station notifies the terminal of the modulation scheme applied to the PDSCH to be transmitted and the size of the data to be transmitted (transport block size (TBS)). In an embodiment, the MCS is composed of 5 bits or more or less 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 to the data.

[0103] In the present invention, a transport block (TB) includes a medium access control (MAC) header, a MAC control element, one or more MAC service data units (SDUs), and padding bits, or a TB represents a unit of data delivered from the MAC layer to the physical layer or a MAC protocol data unit (PDU).

[0104] The modulation methods supported by the NR system are QPSK (quadrature phase shift keying), 16QAM (quadrature amplitude modulation), 64QAM, and 256QAM, with the modulation order (Qm) corresponding to 2, 4, 6, and 8. That is, QPSK modulation allows 2 bits per symbol, 16QAM modulation allows 4 bits per symbol, 64QAM modulation allows 6 bits per symbol, and 256QAM modulation allows 8 bits per symbol.

[0105] 3 and 4 are diagrams showing an example in which eMBB, URLLC, and mMTC data, which are services considered in a 5G or NR system, are allocated in frequency-time resources.

[0106] 3 and 4, it can be seen how frequency and time resources are allocated for information transmission in each system.

[0107] FIG. 3 is a diagram showing an example in which eMBB, URLLC, and mMTC data are allocated to frequency bands across the entire system. First, FIG. 3 shows how data for eMBB, URLLC, and mMTC are allocated across a frequency band 300 across the entire system. When URLLC data (303, 305, 307) is generated and needs to be transmitted while eMBB 301 and mMTC 309 are allocated and transmitted in a specific frequency band, the URLLC data (303, 305, 307) is transmitted without leaving the portion already allocated to eMBB 301 and mMTC 309 or without transmitting the data. Among the above services, URLLC requires a reduction in latency, so the URLLC data (303, 305, 307) is allocated to a portion of the resources 301 allocated to eMBB and transmitted. Of course, if URLLC is additionally allocated and transmitted in resources allocated to eMBB, the eMBB data is not transmitted in the overlapping frequency-time resources, which may result in reduced eMBB data transmission performance. That is, in the above case, failure of eMBB data transmission due to URLLC allocation may occur.

[0108] Figure 4 is a diagram showing an example in which the system frequency band is divided and eMBB 408, URLLC (410, 412, 414), and mMTC 416 data are allocated. In Figure 4, the entire system frequency band 300 is divided and each sub-band (402, 404, 406) is used to transmit services and data. Information related to sub-band configuration is predetermined, and this information is transmitted from the base station to the terminal by higher-level signaling. Alternatively, the base station or network node arbitrarily divides the sub-bands and provides services without transmitting separate sub-band configuration information to the terminal. Figure 4 shows that sub-band 402 is used for eMBB data transmission, sub-band 404 is used for URLLC data transmission, and sub-band 406 is used for mMTC data transmission.

[0109] In order to describe the method and apparatus proposed in this embodiment, the terms physical channel and signal in an NR system are used, although the contents of the present invention are applied to a wireless communication system other than an NR system.

[0110] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Furthermore, when describing the present invention, if a detailed description of related functions or configurations is deemed to obscure the gist of the present invention, such detailed description will be omitted. Furthermore, the terms used below are defined in consideration of the functions of the present invention, and may vary depending on the intentions of users or operators, or practice. Therefore, the definitions should be based on the overall content of this specification.

[0111] In the present invention, downlink (DL) refers to a radio transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a radio transmission path of a signal transmitted from a terminal to a base station.

[0112] Although the following description of the embodiments of the present invention will be given taking an NR system as an example, the embodiments of the present invention can also be applied to other communication systems having similar technical backgrounds or channel configurations. Furthermore, the embodiments of the present invention can be applied to other communication systems with some modifications at the discretion of a person skilled in the art without departing from the scope of the present invention.

[0113] In the present invention, the conventional terms physical channel and signal are used interchangeably with data or control signal. For example, PDSCH is a physical channel on which data is transmitted, but in the present invention, PDSCH may also be referred to as data.

[0114] Hereinafter, in the present invention, higher signaling refers to a signal transmission method transmitted from a base station to a terminal using a downlink data channel of the physical layer, or from a terminal to a base station using an uplink data channel of the physical layer, and is referred to as RRC signaling or MAC control element (MAC CE).

[0115] FIG. 5 illustrates an example of a process in which one transport block is divided into a plurality of code blocks and a CRC is added.

[0116] Referring to FIG. 5, a CRC 503 is added to the end or beginning of a transport block (TB) 501 to be transmitted on the uplink or downlink. The CRC 503 may have 16 or 25 bits, a predetermined number of bits, or a variable number of bits depending on channel conditions, and is used to determine whether channel coding is successful. The TB 501 to which the CRC 503 is added is divided into a plurality of code blocks (CB) (507, 509, 511, 513) (505). Here, the code blocks are divided according to a predetermined maximum size, and in this case, the last code block 513 is smaller in size than the other code blocks (507, 509, 511). However, this is merely an example. As another example, 0, a random value, or 1 may be inserted into the last code block 513 to make the length of the last code block 513 the same as the lengths of the other code blocks (507, 509, 511).

[0117] In addition, CRCs (517, 519, 521, 523) are added to the code blocks (507, 509, 511, 513) respectively (515). The CRC has 16 bits, 24 bits, or a predetermined number of bits, and is used to determine whether the channel coding is successful.

[0118] To generate the CRC503, TB501 and a cyclic generator polynomial are used, where the cyclic generator polynomial can be defined in various ways. For example, suppose the cyclic generator polynomial for a 24-bit CRC is gCRC24A(D) = D24 + D23 + D18 + D17 + D14 + D11 + D10 + D7 + D6 + D5 + D4 + D3 + D+1, and let L = 24. For TIFF0007768970000019.tif6128, CRC This is the value that results in a remainder of 0 when TIFF0007768970000020.tif11155 is divided by gCRC24A(D), TIFF0007768970000021.tif11128 is determined. In the above example, the CRC length L is assumed to be 24, but the CRC length L can be determined to be any of various lengths such as 12, 16, 24, 32, 40, 48, and 64.

[0119] After the CRC is added to the TB through this process, the TB+CRC is divided into N CBs (507, 509, 511, 513). CRCs (517, 519, 521, 523) are added to each of the divided CBs (507, 509, 511, 513) (515). The CRCs added to the CBs have a different length than the CRC added to the TB, or a different cyclic generating polynomial is used to generate the CRC. In addition, the CRC 503 added to the TB and the CRCs (517, 519, 521, 523) added to the code blocks may be omitted depending on the type of channel code applied to the code blocks. For example, if an LDPC code rather than a turbo code is applied to the code blocks, the CRCs (517, 519, 521, 523) inserted for each code block may be omitted.

[0120] However, even when LDPC is applied, CRC (517, 519, 521, 523) can be added to the code block as is. Also, when polar codes are used, CRC can be added or omitted.

[0121] As described above in FIG. 5, the maximum length of one code block of the TB to be transmitted is determined depending on the type of channel coding applied, and the TB and the CRC added to the TB are divided into code blocks according to the maximum length of the code block.

[0122] In conventional LTE systems, a CB CRC is added to the divided CB, and the CB data bits and CRC are encoded into a channel code to determine coded bits, and the number of bits to be rate matched as previously agreed for each coded bit is determined.

[0123] In an NR system, the size of the TB (TBS) is calculated through the following steps:

[0124] Step 1: N' is the number of REs allocated to PDSCH mapping in one PRB in the allocated resources. RE Calculate N' RE teeth Calculated using TIFF0007768970000022.tif11128, where: TIFF0007768970000023.tif9128 is 12, TIFF0007768970000024.tif9128 represents the number of OFDM symbols allocated to the PDSCH. TIFF0007768970000025.tif9128 is the number of REs in 1 PRB occupied by DMRSs of the same CDM group. TIFF0007768970000026.tif9128 is the number of REs occupied by overhead in one PRB set by higher-level signaling, and is set to one of 0, 6, 12, and 18. Then, the total number of REs allocated to the PDSCH, N RE is calculated. N RE is min(156,N′ RE )·n PRB is calculated as n PRB represents the number of PRBs allocated to the terminal.

[0125] Step 2: Number of extra information bits N info teeth, TIFF0007768970000027.tif9128. Here, R is the code rate, Qm is the modulation order, and this value information is transmitted using a pre-defined table as the MCS bit field of DCI. Also, v is the number of allocated layers. Suppose N info If ≦3824, then calculate TBS according to step 3 below. Otherwise, calculate TBS according to step 4.

[0126] Phase 3: TIFF0007768970000028.tif26128 by formula N' info is calculated. TBS is calculated by N' in Table 12 below. info Among the values ​​not smaller than N' info is determined to be the value closest to

[0127] [Table 12]

[0128] Stage 4: TIFF0007768970000030.tif27128 by formula N' info is calculated. TBS is N' info It is determined by the value and the following [pseudo-code1], where C corresponds to the number of code blocks contained in 1TB.

[0129] [Start Pseudo-code1]

[0130] TIFF0007768970000031.tif109133

[0131] [End of Pseudo-code1]

[0132] In an NR system, when one CB is input to the LDPC encoder, a parity bit is added and output. The amount of parity bits varies depending on the LDCP base graph. A method that transmits all parity bits generated by LDPC coding for a specific input is called full buffer rate matching (FBRM), while a method that limits the number of parity bits that can be transmitted is called limited buffer rate matching (LBRM). When resources are allocated for data transmission, the LDPC encoder output is created as a circular buffer, and the bits in the created buffer are repeatedly transmitted as many times as the allocated resources. The length of the circular buffer is called Ncb.

[0133] If the number of all parity bits generated by LDPC coding is N, then in the FBRM method, Ncb = N. In the LBRM method, Ncb is min(N,N ref ) and N ref teeth Given as TIFF0007768970000032.tif14128, R LBRM The decision will be made on February 3rd. TBS LBRM To calculate this, the method for calculating TBS described above is used, but the maximum number of layers and maximum modulation order supported by the terminal in the cell are assumed. The maximum modulation order Qm is assumed to be 8 if the cell is configured to use an MCS table that supports 256QAM for at least one BWP, and 6 (64QAM) if not. The code rate is assumed to be the maximum code rate of 948 / 1024, and NRE is assumed to be 156·n PRB is assumed as n PRB is n PRB,LBRM It is assumed and calculated as: n PRB,LBRM is given by Table 13 below.

[0134] [Table 13]

[0135] The maximum data rate supported by a terminal in an NR system is determined by the following equation 2:

[0136]

number

[0137] In Equation 2, J is the number of carriers aggregated by frequency aggregation, and R max =948 / 1024, TIFF0007768970000035.tif9128 is the maximum number of layers, TIFF0007768970000036.tif9128 denotes the maximum modulation order, f(j) denotes the scaling exponent, and μ denotes the subcarrier spacing. The terminal reports f(j) as one of the values ​​1, 0.8, 0.75, and 0.4, and μ is given by Table 14 below.

[0138] [Table 14]

[0139] Also, TIFF0007768970000038.tif7128 is the average OFDM symbol length, Calculated in TIFF0007768970000039.tif14128, TIFF0007768970000040.tif8128 is the maximum number of RBs in BW(j). OH(j) is the overhead value, given as 0.14 for the downlink and 0.18 for the uplink in FR1 (band below 6 GHz), and as 0.08 for the downlink and 0.10 for the uplink in FR2 (band above 6 GHz). From Equation 2, the maximum data rate in the downlink in a cell with a 100 MHz frequency bandwidth and 30 kHz subcarrier spacing is calculated as shown in Table 15 below.

[0140] [Table 15]

[0141] Meanwhile, the actual data rate that a terminal can measure during actual data transmission is the value obtained by dividing the amount of data by the data transmission time. This is the value obtained by dividing TBS for 1 TB transmission, or the value obtained by dividing the sum of TBS by the TTI length for 2 TB transmission. As an example, in the process of obtaining Table 15, in a cell having a 100 MHz frequency bandwidth with 30 kHz subcarrier spacing, the maximum actual data rate in the downlink is determined according to the number of allocated PDSCH symbols as shown in Table 16 below.

[0142] [Table 16]

[0143] The maximum data rate supported by the terminal can be seen from Table 15, and the actual data rate according to the assigned TBS can be seen from Table 16. In this case, the actual data rate may be higher than the maximum data rate depending on the scheduling information.

[0144] In wireless communication systems, particularly New Radio (NR) systems, a data rate that a terminal can support is mutually agreed upon between a base station and the terminal. This is calculated using the maximum frequency band, maximum modulation order, maximum number of layers, etc. 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 in actual data transmission.

[0145] For this reason, a terminal may be assigned a TBS larger than the value corresponding to the data rate it supports. To prevent this, there are restrictions on the TBS that can be scheduled depending on the data rate supported by the terminal.

[0146] FIG. 6 is a diagram showing how the synchronization signal (SS) and physical broadcast channel (PBCH) of an NR system are mapped in the frequency and time domains.

[0147] The primary synchronization signal (PSS) 601, secondary synchronization signal (SSS) 603, and PBCH are mapped across 4 OFDM symbols, with the PSS and SSS mapped to 12 RBs and the PBCH mapped to 20 RBs. The table in Figure 6 shows how the 20 RB frequency band changes depending on the subcarrier spacing (SCS). The resource region in which the PSS, SSS, and PBCH are transmitted is called an SS / PBCH block. The SS / PBCH block is also called an SSB block.

[0148] FIG. 7 is a diagram showing symbols that can be used to transmit an SS / PBCH block depending on the subcarrier spacing.

[0149] Referring to Figure 7, the subcarrier spacing is set to 15 kHz, 30 kHz, 120 kHz, 240 kHz, etc., and the symbol position where the SS / PBCH block (or SSB block) is located is determined according to each subcarrier spacing. Figure 7 shows the symbol position where the SSB is transmitted according to the subcarrier spacing for symbols within 1 ms, and the SSB is not always transmitted in the area shown in Figure 7. The position where the SSB block is transmitted is set in the terminal by system information or dedicated signaling.

[0150] Because a terminal is generally far from a base station, a signal transmitted from the terminal is received at the base station after a propagation delay. The propagation delay is the path along which a radio wave propagates from the terminal to the base station divided by the speed of light. Generally, it is 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 after approximately 0.34 msec. Conversely, a signal transmitted from the base station is also received at the terminal after approximately 0.34 msec. As described above, the time it takes for a signal transmitted from a terminal to arrive at the base station varies depending on the distance between the terminal and the base station. Therefore, when multiple terminals located at different locations simultaneously transmit signals, the signals arrive at the base station at different times. To solve this problem and ensure that signals transmitted from multiple terminals simultaneously arrive at the base station, the time at which each terminal transmits an uplink signal is varied depending on its location. In 5G, NR, and LTE systems, this is called timing advance.

[0151] Figure 8 is a diagram showing the processing time of a terminal due to timing advance when a terminal receives a first signal and transmits a second signal in response to the first signal in a 5G or NR system according to one embodiment of the present invention.

[0152] The processing time of a terminal due to timing advance will be described in detail below. When a base station transmits an uplink scheduling grant (UL grant) or downlink control signal and data (DL grant and DL data) to a terminal in slot n 802, the terminal receives the uplink scheduling grant or downlink control signal and data in slot n 804. At this time, the terminal receives the signal after a propagation delay time (Tp) 810 from the time when the base station transmitted the signal. In this embodiment, if the terminal receives a first signal in slot n 804, the terminal transmits a corresponding second signal in slot n+4 806. When the terminal transmits a signal to a base station, the terminal transmits a HARQ ACK / NACK for the uplink data or downlink data in slot n+4 806, which is earlier by a timing advance (TA) 812 than slot n+4 of the signal received by the terminal so that the signal arrives at the base station at a specific time. Therefore, in this embodiment, the time during which the terminal receives approval for uplink scheduling, transmits uplink data, or receives downlink data, and prepares to transmit HARQ ACK or NACK is the time corresponding to three slots minus the TA (814).

[0153] To determine the timing, the base station calculates the absolute value of the TA of the terminal. When the terminal initially connects, the base station calculates the absolute value of the TA by adding or subtracting the change in the TA value subsequently transmitted by higher signaling to the TA value initially transmitted to the terminal in a random access phase. In the present invention, the absolute value of the TA is the 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.

[0154] Meanwhile, one of the important performance criteria for cellular wireless communication systems is packet data latency. To achieve this, LTE systems transmit and receive signals in subframe units with a transmission time interval (TTI) of 1 ms. The LTE system, which operates as described above, supports terminals with transmission time intervals shorter than 1 ms (short-TTI UEs). Meanwhile, 5G or NR systems have transmission time intervals shorter than 1 ms. Short-TTI terminals are suitable for latency-sensitive services such as Voice over LTE (VoLTE) and remote control. Furthermore, short-TTI terminals are a means of realizing cellular-based mission-critical Internet of Things (IoT).

[0155] In a 5G or NR system, when a base station transmits a PDSCH including downlink data, the DCI scheduling the PDSCH indicates a K1 value, which is a value corresponding to timing information at which a terminal transmits HARQ-ACK information of the PDSCH. If the HARQ-ACK information is not instructed to be transmitted before symbol L1 including a timing advance, the terminal transmits the HARQ-ACK information to the base station. That is, the HARQ-ACK information is transmitted from the terminal to the base station at the same time as or after 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 is not valid HARQ-ACK information for HARQ-ACK transmission from the terminal to the base station.

[0156] Symbol L1 is T from the end of the PDSCH proc,1 is the first symbol after which a cyclic prefix (CP) begins. proc,1 is calculated as in Equation 3 below.

[0157]

number

[0158] In the above equation 3, N1, d1,1, d 1,2 ,κ,μ,T C is defined as follows:

[0159] When HARQ-ACK information is transmitted on the PUCCH (Uplink Control Channel), 1,1 = 0 and transmitted on PUSCH (uplink shared channel, data channel), 1,1 =1.

[0160] If the terminal is configured with multiple activated constituent carriers or carriers, the maximum timing difference between the carriers is reflected in the transmission of the second signal.

[0161] In the case of PDSCH mapping type A, i.e., when the first DMRS symbol position is the third or fourth symbol of the slot, if the position index i of the last PDSCH symbol is less than 7, d 1,2 = 7 - i.

[0162] In the case of PDSCH mapping type B, i.e., when the first DMRS symbol position is the first symbol of the PDSCH, if the PDSCH length is 4 symbols, d 1,2 = 3 and the length of the PDSCH is 2 symbols, then d 1,2 = 3 + d, where d is the number of symbols overlapping the PDSCH and the PDCCH containing the control signal that schedules the PDSCH.

[0163] -N1 is defined by μ as shown in Table 17 below, where μ=0, 1, 2, 3 means subcarrier spacing of 15 kHz, 30 kHz, 60 kHz, 120 kHz, respectively.

[0164] [Table 17]

[0165] The N1 value provided in Table 17 above is different depending on the UE capability.

[0166] TIFF0007768970000045.tif24139, respectively.

[0167] In addition, in a 5G or NR system, when a base station transmits control information including an approval for uplink scheduling, the base station indicates a K2 value corresponding to timing information for the terminal to transmit uplink data or PUSCH.

[0168] If the PUSCH is not instructed to be transmitted before symbol L2 including a timing advance, the terminal transmits the PUSCH to the base station. That is, the PUSCH is transmitted from the terminal to the base station at the same time as or after symbol L2 including a timing advance. If the PUSCH is instructed to be transmitted before symbol L2 including a timing advance, the terminal ignores the uplink scheduling admission control information from the base station.

[0169] Symbol L2 is T from the end of the PDCCH containing the scheduling acknowledgement. proc,2 is the first symbol after which the CP of the PUSCH symbol to be transmitted begins. proc,2 is calculated as in Equation 4 below.

[0170]

number

[0171] In the above equation 4, N2, d 2,1 , κ, μ, and TC are defined as follows:

[0172] If the first symbol among the symbols to which PUSCH is assigned contains only DMRS, 2,1 =0, otherwise d 2,1 =1.

[0173] If the terminal is configured with multiple activated constituent carriers or carriers, the maximum timing difference between the carriers is reflected in the transmission of the second signal.

[0174] -N2 is defined by μ as shown in Table 18 below, where μ=0, 1, 2, 3 means subcarrier spacing of 15 kHz, 30 kHz, 60 kHz, 120 kHz, respectively.

[0175] [Table 18]

[0176] The N2 value provided in Table 18 above varies depending on the UE capability.

[0177] TIFF0007768970000048.tif21146, respectively.

[0178] Meanwhile, a 5G or NR system configures a frequency band part (BWP) within one carrier and specifies that a specific terminal transmits and receives within the configured BWP. This is intended to reduce the power consumption of the terminal. A base station configures multiple BWPs and changes the activated BWP in control information. The time available for a terminal to change the BWP is defined as shown in Table 19 below.

[0179] [Table 19]

[0180] In Table 19, Frequency Range 1 refers to the frequency band below 6 GHz, and Frequency Range 2 refers to the frequency band above 6 GHz. In the above embodiment, Type 1 and Type 2 are determined by the capability of the UE. In the above embodiment, Scenarios 1, 2, 3, and 4 are given as shown in Table 20 below.

[0181] [Table 20]

[0182] 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 based on the feedback. In FIG. 9, TB1 900 is initially transmitted in slot 0 902, and a corresponding ACK / NACK feedback 904 is transmitted in slot 4 906. If the initial transmission of TB1 fails and a NACK is received, a retransmission 910 for TB1 is performed in slot 8 908. Here, the times at which the ACK / NACK feedback is transmitted and the retransmission are performed are predetermined or determined by values ​​indicated by control information and / or higher layer signaling.

[0183] 9 shows an example in which TB1 to TB8 are scheduled and transmitted sequentially starting from slot 0. This means that HARQ process IDs 0 to 7 are assigned to TB1 to TB8, respectively, for transmission. If the number of HARQ process IDs available to the base station and terminal is only four, transmission to eight different TBs cannot be performed consecutively.

[0184] 10 is a diagram showing an example of a communication system using a satellite. For example, when a terminal 1001 transmits a signal to a satellite 1003, the satellite 1003 transmits the signal to a base station, the base station processes the received signal, and transmits a signal including a request for subsequent operation to the terminal 1001, which is again transmitted via the satellite 1003. Here, since the distance between the terminal 1001 and the satellite 1003 is long and the distance between the satellite 1003 and the base station is also long, it ultimately takes a long time for data to be transmitted and received from the terminal 1001 to the base station.

[0185] FIG. 11 shows the Earth's orbital period of communication satellites as a function of their altitude or height. Communication satellites are classified into low Earth orbit (LEO), middle Earth orbit (MEO), and geostationary Earth orbit (GEO) satellites according to their orbits. Generally, GEO1100 refers to a satellite at an altitude of approximately 36,000 km, MEO1110 refers to a satellite at an altitude of 5,000 to 15,000 km, and LEO refers to a satellite at an altitude of 500 to 1,000 km. The Earth's orbital period varies depending on the altitude, with GEO1100 being approximately 24 hours, MEO1110 being approximately 6 hours, and LEO1130 being approximately 90 to 120 minutes. Low Earth orbit (up to 2,000 km) satellites are at a relatively low altitude and have advantages in terms of propagation delay time and loss compared to geostationary orbit (36,000 km) satellites.

[0186] 12 shows the concept of satellite-terminal direct communication. A satellite 1200, which is launched by a rocket at an altitude of 100 km or more, transmits and receives signals to and from a terminal 1210 on the ground, and also transmits and receives signals to and from a ground station 1220 connected to a terrestrial base station (DU farm) 1230.

[0187] Figure 13 illustrates a scenario for satellite-to-terminal direct communication. Satellite-to-terminal direct communication can support specialized communication services by complementing the coverage limitations of terrestrial networks. For example, implementing satellite-to-terminal direct communication functionality in a user terminal enables users to send and receive emergency rescue and / or distress signals outside of terrestrial network coverage (1300), provides mobile communication services to users in areas where terrestrial network communication is unavailable, such as on ships and / or in the air (1310), and enables real-time tracking and control of the positions of ships, cargo vehicles, and / or drones without border restrictions (1320). Furthermore, providing a satellite communication function to a base station allows it to function as a backhaul for the base station, enabling satellite communication to be used to perform the backhaul function when physically far away (1330).

[0188] Figure 14 shows an example of the calculation of the expected data throughput in the uplink when a LEO satellite at an altitude of 1,200 km communicates directly with a terrestrial terminal. If the terrestrial terminal transmits an effective isotropic radiated power (EIRP) of 23 dBm in the uplink, 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 includes the path loss in space and the loss in the atmosphere. Assuming a signal-to-interference ratio (SIR) of 2 dB, the signal-to-interference and noise ratio (SINR) is calculated to be -3.92 dB, and a transmission speed of 112 kbps can be achieved using a 30 kHz subcarrier spacing and a frequency resource of 1 PRB.

[0189] Figure 15 shows an example of the expected data throughput calculation for the uplink when a GEO satellite at an altitude of 35,786 km communicates directly with a terrestrial terminal. For the uplink, if the terrestrial terminal transmits 23 dBm EIRP, 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 includes path loss in space and loss in the atmosphere. Assuming an SIR of 2 dB, the SINR is calculated to be -11 dB. In this case, using a subcarrier spacing of 30 kHz and a frequency resource of 1 PRB, a transmission speed of 21 kbps is achievable. This is the result of three repeated transmissions.

[0190] FIG. 16 is a diagram showing path loss values ​​according to a path loss model between a terminal and a satellite, and path loss according to a path loss model between a terminal and a terrestrial network communication base station. In FIG. 16, d corresponds to distance, and fc is the signal frequency. In free space where communication between a terminal and a satellite takes place, 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 network communication base station (terrestrial gNB) takes place, the path loss (PL2, PL') is inversely proportional to the square of the distance. Uma-NLOS )(1610, 1620) is inversely proportional to the fourth power of the distance. 3D means the straight-line distance between the terminal and the base station, and h BS is the height of the base station, and h UT is the height of the terminal. d' BP =4×h BS ×h UT ×f c It is calculated as f / c. c is the center frequency in Hz and c is the speed of light in m / s.

[0191] In satellite communications (also known as non-terrestrial networks), the fast-moving satellites cause Doppler shifts, which are frequency offsets of transmitted signals.

[0192] 17 is a diagram showing the formula and results for calculating the amount of Doppler shift that a signal transmitted from a satellite undergoes when received by a terrestrial user, depending on the altitude and position of the satellite and the position of the terrestrial user. The radius of the Earth is R, h is the altitude of the satellite, v is the speed at which the satellite revolves around the Earth, and f c is the frequency of the signal. The satellite velocity is calculated from the satellite altitude, which is the velocity at which the gravity, the force pulling the satellite from the Earth, and the centripetal force generated by the satellite's revolution become equal, and is calculated as shown in Figure 18. Figure 18 is a diagram showing the satellite velocity calculated from the satellite altitude. As can be seen from Figure 17, each α is determined by the elevation angle θ, so the Doppler shift value is determined by the elevation angle θ.

[0193] Figure 19 is a diagram showing the Doppler shift experienced by individual terminals located within a single beam transmitted from a satellite to the ground. In Figure 19, the Doppler shift experienced by terminal 1 1900 and terminal 2 1910 is calculated based on the altitude angle θ. The results assume a center frequency of 2 GHz, a satellite altitude of 700 km, a beam diameter of 50 km on the ground, and terminal speed of 0. In addition, the Doppler shift calculated in this specification ignores the effect of the Earth's rotational speed, which can be considered to have little impact because it is slower than the satellite speed.

[0194] 20 is a diagram showing the difference in Doppler shift that occurs within a beam depending on the satellite's position as determined by the altitude angle. It can be seen that the difference in Doppler shift within a beam (or cell) is greatest when the satellite is located directly above the beam, i.e., when the altitude angle is 90°. This is because when the satellite is in the center, the Doppler shift values ​​at one end and the other end of the beam have positive and negative values, respectively.

[0195] On the other hand, in satellite communications, since the satellite is far from the user on the ground, a longer delay time occurs compared to terrestrial network communications.

[0196] Figure 21 shows the delay time from a terminal to a satellite and the round-trip delay time between the terminal, satellite, and base station depending on the satellite's position, as determined by the altitude angle. 2100 indicates the delay time from the terminal to the satellite, and 2110 indicates the round-trip delay time between the terminal, satellite, and base station. Here, it is assumed that the delay time between the satellite and base station is the same as the delay time between the terminal and the satellite. Figure 22 shows the maximum difference in round-trip delay time that varies depending on the user's position within a beam. For example, when the beam radius (or cell radius) is 20 km, the difference in round-trip delay time between terminals at different positions within the beam and the satellite can be considered to be approximately 0.28 ms depending on the satellite's position.

[0197] In satellite communications, when a mobile station transmits and receives a signal to a base station, the signal is transmitted via a satellite. That is, in downlink, the base station transmits a signal to the satellite, which receives the signal and then transmits it to the mobile station. In uplink, the mobile station receives a signal and then transmits it to the base station. Here, after receiving the signal, the satellite either performs frequency shifting and then transmits the signal, or performs signal processing such as decoding and re-encoding based on the received signal and then transmits it.

[0198] In LTE or NR, a terminal connects to a base station according to the following procedure.

[0199] Step 1: The terminal receives a synchronization signal (or SSB (synchronization signal block), which includes a broadcast signal) from the base station. The synchronization signal includes a PSS (primary synchronization signal), an SSS (secondary synchronization signal), and a PBCH (physical broadcast channel). The synchronization signal includes information such as slot boundaries, frame numbers, downlink and uplink configurations of signals transmitted by the base station. In addition, the terminal obtains subcarrier offsets, scheduling information for system information transmission, etc. from the synchronization signal.

[0200] Step 2: The terminal receives system information (SIB) from the base station. The SIB includes information for initial connection and random access. The information for random access includes resource information for transmitting a random access preamble.

[0201] Step 3: A random access preamble (or message 1: msg1) is transmitted to the random access resource set in step 2. The preamble is a signal determined based on the information set in step 2 using a predetermined number sequence. The base station receives the preamble transmitted by the terminal. The base station attempts to receive the preamble set by the base station itself on the resource set by the base station without knowing which terminal sent the preamble. If the reception is successful, the base station knows that at least one terminal has sent a preamble.

[0202] Step 4: Upon receiving the preamble 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 attempts 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 before the RAR. A CRC scrambled with the 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 for transmission. The RA-RNTI is determined based on the time and frequency resources in which the preamble in step 3 is transmitted.

[0203] The maximum time limit for a terminal that transmitted a random access preamble in step 3 to receive an RAR in this step is set in the SIB transmitted in step 2. This is set to a limit of, for example, a maximum of 10 ms or 40 ms. That is, if a terminal that transmitted a preamble in step 3 cannot receive an RAR within a time determined based on the set maximum time of, for example, 10 ms, it transmits a preamble again. The RAR includes scheduling information that allocates resources for a signal that the terminal will transmit in the next step, step 5.

[0204] 23 is a diagram showing an example of the information structure of an RAR. The RAR 2300 is, for example, a MAC PDU, and also includes information 2310 related to a timing advance (TA) applied by the terminal and a temporary C-RNTI value 2320 used in the next stage.

[0205] 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 transmits msg3 including its own unique ID value. The base station attempts to receive msg3 according to the scheduling information it transmitted in step 4.

[0206] - Step 6: The base station receives msg3, checks the ID information of the terminal, and then generates message 4 (msg4) including the ID information of the terminal and sends it to the terminal. The terminal that sent msg3 in step 5 attempts to receive msg4, which will be sent in the following step 6. After receiving msg4, the terminal compares the ID value included in msg4 with the ID value it sent in step 5 after decoding to check whether the msg3 it sent was received by the base station. There is also a limit to the time until the terminal receives msg4 in this step after sending msg3 in step 5, and this maximum time is also set by the SIB in step 2.

[0207] When the initial connection procedure using the above steps is applied to satellite communications, the propagation delay time in satellite communications becomes a problem. For example, the period (random access window) during which the terminal transmits a random access preamble (or a PRACH preamble) in step 3 and receives an RAR in step 4, i.e., the maximum time until reception, is set by the ra-ResponseWindow. In conventional LTE or 5G NR systems, this maximum time is set to a maximum of approximately 10 ms.

[0208] Figure 24 is a diagram showing an example of the relationship between PRACH preamble configuration resources and RAR reception times in an LTE system, and Figure 25 is a diagram showing an example of the relationship between PRACH preamble configuration resources and RAR reception times in a 5G NR system. Referring to Figure 24, in LTE, a random access window 2410 starts 3 ms after transmitting a PRACH (random access preamble) 2400, and a terminal determines that the PRACH preamble has been transmitted successfully if it receives an RAR 2420 within the random access window. Referring to Figure 25, in NR, after transmitting a PRACH (random access preamble) 2500, the random access window 2510 starts from the first control information field for RAR scheduling. If the terminal receives an RAR 2520 within the random access window, it determines that the PRACH preamble has been transmitted successfully.

[0209] As an example, the TA value for uplink transmission timing in a 5G NR system is determined as follows: It is determined to be TIFF0007768970000051.tif9146, where TIFF0007768970000052.tif11146. Also, TIFF0007768970000053.tif20146, respectively.

[0210] FIG. 26 is a diagram illustrating an example of downlink frame and uplink frame timing in a terminal. The terminal determines uplink frames based on downlink frame timing. TIFF0007768970000054.tif8132 is advanced by N TA The value of is signaled by the RAR or determined based on the MAC CE, and N TA,offset is a value that is set in the terminal or determined based on a predetermined value.

[0211] In the RAR of the 5G NR system, a TA value is specified, and the TA value is specified as one of 0, 1, 2, ..., 3846. In this case, the subcarrier spacing (SCS) of the RAR is 2 μ If 15kHz, N TA teeth TIFF0007768970000055.tif8132. After the terminal completes the random access procedure, the base station indicates the change value of TA, which is indicated by the MAC CE. The TA information indicated by the MAC CE is one of the values ​​0, 1, 2, ..., 63, which is added or subtracted from the existing TA value to calculate a new TA value, and the resulting TA value is TIFF0007768970000056.tif8132. The TA value thus instructed is applied to the terminal's uplink transmissions after a certain period of time.

[0212] 27A is a diagram showing an example of the continuous movement of a satellite on the Earth's surface or at a terminal located on the Earth as the satellite revolves around the Earth along a satellite orbit. The distance between the terminal and the satellite changes depending on the elevation angle at which the terminal views the satellite, and therefore the propagation delay between the terminal, the satellite, and the base station changes.

[0213] FIG. 27B is a diagram showing an example of the structure of an artificial satellite. The satellite is composed of a solar panel or solar array 2700 for generating electricity using sunlight or solar heat, a transmitting / receiving antenna (main mission antenna) 2710 for communicating with terminals, a transmitting / receiving antenna (feeder link antenna) 2720 for communicating with a ground station, a transmitting / receiving antenna (inter-satellite link) 2730 for inter-satellite communication, and a processor for controlling transmission and reception and performing signal processing, etc. Here, if the satellite does not support inter-satellite communication, an antenna for inter-satellite signal transmission and reception is not provided. In FIG. 27B, the L-band of 1 to 2 GHz is used for communication with terminals, but 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) can also be used.

[0214] In terminal-satellite direct communication, the distance between the terminal and satellite and the satellite and base station is long, and the satellite is constantly moving, so when a signal transmitted from the base station or the terminal is received by the terminal or the base station, a time offset occurs due to delay time, etc. Therefore, the present invention provides a method and apparatus in which the base station indicates time offset information so that the time offset can be corrected, and the terminal corrects accordingly. The following embodiments will be described assuming communication between the terminal and a satellite and a ground station, but the case where a satellite base station and a terminal communicate with each other is not excluded. In the present invention, time offset is used synonymously with timing advance.

[0215] [First Example]

[0216] The first embodiment provides a method and apparatus in which a base station indicates time offset information to a terminal, and the terminal applies the indicated value.

[0217] The terminal estimates the delay time between the satellite and the terminal based on its own position and the position of the satellite, corrects the estimated delay time value by itself, and performs uplink transmission. For example, a satellite broadcasts information about its position, and the terminal receives the satellite's position information and compares it with its own position. The terminal determines its own position using a global positioning system (GPS). Based on the comparison, the terminal estimates the time it takes for radio waves to travel to the satellite and calculates the uplink transmission time. For example, if the terminal receives a signal in downlink slot n at a specific time and must perform uplink transmission corresponding to the signal in slot n+k, the uplink transmission is transmitted 2 × Td earlier than slot n+k. Here, Td is the delay time from the terminal to the satellite calculated based on the position information of the satellite and the terminal. The delay time Td is the distance from the terminal to the satellite divided by the speed of light. Here, the satellite position is calculated based on slot n+k in which the terminal performs uplink transmission. This is because the satellite's position in slot n and the satellite's position in slot n+k change due to the satellite's motion.

[0218] Figure 28 shows an example of the difference in propagation delay time between terrestrial and satellite networks. In terrestrial networks, propagation delay times of less than 1 ms occur, taking into account the maximum distance to a base station of approximately 100 km. However, in satellite networks, the distance to the satellite is several thousand kilometers, and the distance from the satellite to the base station is also several thousand kilometers, resulting in much larger delay times than in terrestrial networks. In satellite network communications, delay times vary depending on the satellite's altitude and altitude angle. Figure 28 shows the terminal-satellite distance and the time it takes for radio waves to travel round trip depending on the altitude angle when the satellite's altitude is 700 km. In satellite networks, assuming a low-orbit satellite and an altitude angle between 0 and 180 degrees, the radio round trip time (radio RTT, which includes the round-trip time for a signal to be transmitted between a transmitter and a receiver and the processing time at the destination node) ranges from 40.9 ms to 9.3 ms.

[0219] 29 is a diagram showing an example of applying timing advance in a terrestrial network and a satellite network. In a terrestrial network, since the maximum delay time is within 1 or 2 ms, the timing advance provided by the LTE and 5G NR systems is used to match the slot timing for transmitting downlink signals from the base station with the slot timing for receiving uplink signals (i.e., the DL slot and UL slot indexes match). That is, if a terminal transmits uplink signals earlier than the downlink time by the timing advance value specified by the base station, the uplink signal transmitted by the terminal will be received by the base station at the same time as the downlink time of the base station.

[0220] On the other hand, in satellite networks, it is impossible to use the timing advance provided by conventional LTE and 5G NR systems to match the slot timing for transmitting downlink signals and the slot timing for receiving uplink signals at the base station. This is because the propagation delay time in satellite networks is large, on the order of tens of milliseconds, and this propagation delay time is larger than the maximum value of the timing advance provided by conventional LTE and 5G NR systems.

[0221] 30 shows an example of the maximum difference in round-trip propagation delay time between a mobile station, a satellite, and a base station experienced by multiple users located within one of multiple beams transmitted by a satellite. The smaller the beam size, the smaller the difference in round-trip propagation delay time due to the altitude angle experienced by the users.

[0222] Figure 31A shows an example of the round-trip propagation delay time between a terminal and a base station, which changes as the satellite moves along its orbit. As the satellite moves along its orbit, Figure 31A shows that the round-trip propagation delay time between a terminal and a base station changes over time. While the delay time changes (within a certain time period) in a terrestrial network, the satellite network shows a very large change in delay time over time.

[0223] The satellite indicates time offset information to the terminal using the following method, and the terminal corrects the transmission time using the time offset information indicated by the following method to transmit or receive downlink or uplink signals.

[0224] Method 1: The delay time indication range or the size of the bit field for indicating the delay time or the timing advance is determined based on the frequency domain or frequency band (frequency band, spectrum). As an example, the RAR MAC CE includes 12 bits of TA information in the frequency domain having a center frequency of 1 GHz or less, and 16 bits of TA information in the frequency domain having a center frequency of more than 1 GHz.

[0225] - Method 2: The base station instructs the rate of change of the timing advance. Because satellites move regularly over time, the delay time changes linearly in a specific time interval. Therefore, the base station instructs the terminal about the rate of change of the delay time or timing advance, and instructs the terminal how to change and apply the TA in the future. The rate of change of the time offset (or timing advance) corresponds to the amount of change in the TA to be applied at a specific point in the future. While instructing the rate of change of the time offset, the base station also instructs the terminal in advance, or in advance, the time period and time point at which the time offset change rate is to be applied, via L1 control information (e.g., DCI) or sets it via higher level signaling. The higher level signaling is MAC CE or RRC signaling, not physical layer signaling.

[0226] Method 3: A TA value or a change rate is indicated to one or more terminals in a group (group-common) by the same DCI or the same MAC CE. According to this method, a TA value or a change rate is indicated to one or more terminals by the same instruction information field, or a timing advance or a change rate is indicated to each terminal by a different instruction information field. When a TA value or a change rate is indicated to different terminals by different instruction information fields, the position of the bit field to be analyzed by the terminal or the offset value of the bit field position are preset. The terminal checks the bit field value applied to itself from the bit field position or the position offset information. FIG. 31B is a diagram showing an example in which multiple terminals are located within one beam area provided by one satellite. As shown in FIG. 31B, terminals located within one beam area provided by a satellite transmit and receive signals to and receive signals from the same satellite, and therefore have similar delay time and Doppler shift change values. Therefore, the terminals (UE1, UE2, UE3, UE4, and UE5) in FIG. 31A located in one beam area perform time offset correction to correct the delay time or timing advance value according to the same instruction information.

[0227] Figure 31C is a diagram showing an example of instructing a time offset to a group of terminals using one MAC CE. According to Figure 31C, when a time offset is instructed to a group of terminals (3110, 3112, 3114, 3116, 3118, 3120, 3122, 3124, 3126) on a group-by-group basis using the same MAC CE 3100, one MAC CE includes time offset indication information for multiple terminals. The start position 3130 of the time offset indicator for each terminal is preset by higher layer signaling. In addition to the MAC CE, time offset indication information is also transmitted on a group-by-group basis by DCI, and in this case, a bit field indicating multiple TA values ​​becomes part of the DCI. In this case, for example, a DCI format including a bit field indicating multiple TA values ​​is used, and the terminals in the group perform blind decoding using RNTI values ​​that are predefined or set by higher layer signaling.

[0228] Method 4: Using SIB, indicate the TA value that must be commonly applied by terminals corresponding to a specific beam in the system information. For example, the time offset TA _offset TA _offset1 +TA _offset2 where TA _offset1 is a value that is set or instructed commonly to terminals belonging to the beam, and TA _offset2 is a value set or specified for a particular terminal. _offset2 is set using at least one of the methods described above.

[0229] Method 5: The base station configures the time offset unit for the terminal through RRC configuration. When the base station indicates the time offset unit through RRC configuration and indicates the number of time offset units in MAC CE or DCI, the terminal calculates the accurate time offset value using the time offset unit. As another variant, the base station indicates candidate values ​​for the time offset unit through RRC configuration and indicates one of them in MAC CE or DCI. Candidate values ​​for the time offset unit are configured within a specified range through RRC signaling, and if only one value is configured as a candidate value, the value configured without MAC CE or DCI is applied.

[0230] Method 6: The time offset value is configured in the terminal through RRC configuration. As another example, the time offset value is transmitted to the terminal through a combination of RRC configuration and MAC CE.

[0231] These methods are not mutually exclusive, and one or more of these methods may be used in combination.

[0232] [Second Example]

[0233] The second embodiment provides a method and apparatus for a base station or a satellite to indicate a TA value to a terminal. In the present invention, a satellite is an object located high above the ground, and is a concept that includes airplanes, airships, etc.

[0234] 32 and 33 are diagrams illustrating an example in which a satellite or beam serving a terminal changes due to satellite movement when the satellite transmits and receives signals using multiple beams. FIG. 32 illustrates an example in which the beam or satellite to which the terminal is connected (or receives service) changes, but the terrestrial base station or earth station connected to the terminal does not change. As a specific example, in (3200), terminal 3210 is connected to satellite 1 3220 and communicates with earth station 3240. If the satellite's position changes due to satellite movement as in (3250), terminal 3210 is connected to satellite 1 3220 and communicates with earth station 3240, but the beam used for connection with satellite 1 changes, or terminal 3210 is connected to satellite 2 3230 and communicates with earth station 3240. FIG. 33 illustrates an example in which the terrestrial base station or earth station connected to the terminal also changes when the beam or satellite to which the terminal is connected (or receives service) changes. As a specific example, in (3300), terminal 3310 is connected to satellite 1 3320 and communicates with earth station 1 3340, and when the satellite's position changes due to satellite movement as in (3360), terminal 3310 is connected to satellite 2 3330 and communicates with earth station 2 3350.

[0235] In the above, when the satellite or beam transmitting a signal to the terminal is changed, the timing advance (TA) value for uplink time synchronization may be suddenly and significantly changed. In this case, the base station must notify the terminal of the changed TA value to prevent signal interference with signals transmitted by other terminals. To notify a large change in the TA value, the number of bits of the TA indicator may be increased or the granularity or unit of the TA value indicated by the bit value may be set to a larger value. Alternatively, to notify the TA value again, the terminal may restart the random access procedure when the satellite or beam transmitting and receiving signals to the terminal is changed. However, frequent changes in the satellite and / or beam increase the overhead of the random access procedure, resulting in a decrease in data transmission rate and service quality.

[0236] The present invention provides a TA indication method and apparatus for transmitting a TA value that is suddenly and significantly changed to a terminal.

[0237] The terminal and the base station store multiple TA value candidates. For example, the terminal and the base station store four TA candidate values, respectively, and the terminal continues to update the four TA candidate values ​​or applies the corresponding value as the actual TA value according to the instruction of the base station. Each TA candidate value is called a TA loop.

[0238] The base station notifies the terminal of a TA loop index in the process of instructing the terminal of a TA value, thereby indicating which TA value the terminal should update or apply. Figure 34 shows an example of a TA loop. When the terminal 3400 is connected to more than one satellite (3410, 3420) or changes connection from one satellite 3410 to another satellite 3420, multiple TA loops are defined to apply different TA values ​​(e.g., TA loop 1 3412 applied to satellite 1 3410 and TA loop 2 3422 applied to satellite 2 3420 are configured), and this shows an example understood by the base station and the terminal. The terminal is notified of the TA value to be applied to the terminal for uplink transmission in the random access (RACH) phase in the process of connecting with a base station. The TA value transmitted in the RACH phase is determined as the TA value of TA loop index 0. Thereafter, other TA candidate values ​​are also configured in the terminal. The TA candidate values ​​thus configured are assigned index numbers such as TA loop index 1, 2, and 3. Table 21 shows the TA loop values ​​set in the terminal. TA loop indexes 0 to 3 correspond to the set TA values, and each TA value is different.

[0239] [Table 21]

[0240] In the above, the number of TA loops is configured by the base station to the terminal through higher signaling such as RRC signaling or MAC CE. Here, the signaling for the base station to configure the number of TA loops to the terminal is transmitted to the terminal via a satellite. Alternatively, the number of TA loops may be determined to a fixed value or may be a value configured based on the terminal's capability. The terminal reports UE capability information related to the number of TA loops it can support to the base station.

[0241] To indicate one of the TA loop values, the base station indicates the index of the TA loop to the terminal using one bit field of the DCI or the value of the MAC CE. For example, the base station indicates a TA loop index using some bits of the DCI to indicate a TA value to be applied by the terminal while scheduling a PUSCH, which is uplink data, using the DCI, and the terminal transmits the scheduled PUSCH by applying the TA value corresponding to the indicated TA loop. Or / and, for example, the base station indicates the index of the TA loop to be applied by the terminal using the MAC CE and applies a TA modification value indicated by the MAC CE to the TA value corresponding to the indicated TA loop. In this case, the MAC CE includes one or more TA loop indexes and TA modification values ​​for the TA loop indexes.

[0242] 35A and 35B illustrate an example of the operation of a base station and a terminal for changing such a TA value. FIG. 35A illustrates an example of the operation of a base station for indicating a TA value. The base station configures the number of TA loops to the terminal through higher level signaling. This configuration is performed by transmitting information on the number of TA loops or by transmitting configuration information for the index of each TA loop. This configuration is performed based on UE capability information related to the TA loop transmitted by the terminal (step 3500). The base station indicates the TA loop index to the terminal using a part of a bit field included in L1 control information (e.g., DCI) (step 3510). The base station indicates a TA change value for the TA value of the indicated TA loop index using MAC CE transmitted on the PDSCH (step 3520).

[0243] FIG. 35B illustrates an example of a terminal operation for indicating a TA value. The terminal receives the number of TA loops from the base station through higher-layer signaling. This setting is performed by receiving information about the number of TA loops or by receiving setting information for each TA loop index. The terminal transmits UE capability information related to the terminal's TA loops to the base station (step 3530). The terminal receives L1 control information (e.g., DCI) and acquires the indicated TA loop index using a bit field included in the DCI (step 3540). The terminal receives a TA change value for the TA value of the indicated TA loop index via a MAC CE received on the PDSCH (step 3550). The terminal uses the applied TA value for uplink transmission. The steps disclosed in FIGS. 35A and 35B may be applied in a different order, and other steps may be added or omitted.

[0244] The UE applies the determined TA value to HARQ ACK / NACK feedback transmission, uplink data transmission, or PUSCH, PUCCH transmission, etc. Figures 36A and 36B are diagrams illustrating an example of the operation of a base station and a UE transmitting a PUSCH by applying an instruction for a TA value. Figure 36A is a diagram illustrating an example of the operation of a base station transmitting a PUSCH by applying an instruction for a TA value. The base station configures the number of TA loops to the UE through upper signaling. This configuration is performed by transmitting information about the number of TA loops or by transmitting configuration information for the index of each TA loop. This configuration is performed based on UE capability information related to the TA loop transmitted by the UE (step 3600). The base station checks the TA value that the UE should apply when receiving a PUSCH and checks the TA loop index for indicating the TA value (step 3610). The base station transmits an UL grant to the UE to schedule a PUSCH, and the UL grant includes a bit field indicating a TA loop index and a bit field indicating resource allocation information for PUSCH transmission (step 3620).

[0245] Figure 36B illustrates an example of the operation of a terminal transmitting a PUSCH by applying a TA value instruction. The number of TA loops is configured in the terminal from the base station through higher-level signaling. This configuration is performed by receiving information on the number of TA loops or by receiving configuration information for each TA loop index. This configuration is performed based on UE capability information related to the TA loop transmitted by the terminal (step 3630). The terminal receives an UL grant for scheduling a PUSCH from the base station, and the UL grant includes a bit field indicating a TA loop index and a bit field indicating resource allocation information for PUSCH transmission. The terminal checks the TA loop index indicated by the base station based on the bit field (step 3640). The terminal checks the TA value corresponding to the TA loop index and transmits a PUSCH by applying the TA value (step 3650). The steps disclosed in Figures 36A and 36B may be applied in a different order, or other steps may be added or omitted.

[0246] In the above, indicating a TA loop index with some bits of the DCI means that the DCI is for uplink scheduling, and the UE performs uplink transmission scheduled by the DCI using a TA value corresponding to the indicated TA loop index. Alternatively, if the DCI is for scheduling downlink data and indicates a TA loop index, the UE applies the TA value corresponding to the indicated TA loop index when transmitting a PUCCH for transmitting a HARQ-ACK corresponding to the downlink data.

[0247] Furthermore, the DCI is a DCI for scheduling downlink data, and includes a bit field indicating a TA value or a TA change value, or corresponds to a separate DCI format indicating a TA value or a TA change value. In this case, if a TA loop index is indicated by the DCI, the change indicated by the DCI is applied only to the TA value of the corresponding index, or if a TA loop index is not included in the DCI, the change indicated by the DCI is applied to the TA values ​​corresponding to all TA loops. Whether a TA loop index is included and indicated in the DCI is set by upper signaling of the base station and / or determined based on the number of TA loops supported by the terminal (i.e., the terminal's capabilities).

[0248] Furthermore, in the case of a DCI that schedules downlink data, the base station indicates a TA value or a TA change value by a MAC CE transmitted via a PDSCH scheduled by the DCI. In this case, if a TA loop index is indicated by the DCI, the change indicated by the MAC CE is applied only to the TA value of the corresponding index, or if a TA loop index is not included in the DCI, the change indicated by the MAC CE is applied to the TA values ​​corresponding to all TA loops. Whether a TA loop index is included and indicated in the DCI is set by upper signaling of the base station and / or determined based on the number of TA loops supported by the terminal (i.e., the terminal's capabilities).

[0249] As described above, if a TA value or a TA change value is indicated in a MAC CE transmitted via a PDSCH scheduled by a DCI for scheduling downlink data or a separate DCI format or the DCI for scheduling downlink data, the UE applies the applied TA value to a PUSCH or PUCCH transmission to be scheduled later. If a TA loop index is included and indicated in a DCI for scheduling downlink data or a separate DCI format, the UE applies the TA value of the TA loop index indicated in the DCI to a PUSCH or PUCCH transmission to be scheduled later, and the DCI for scheduling a PUSCH to be scheduled later or the DCI for scheduling a PDSCH related to a PUCCH (or HARQ-ACK) does not include a bit field indicating a TA loop index.

[0250] [Third Example]

[0251] The third embodiment provides a method and apparatus for a terminal to transmit (report) to a base station or satellite a timing advance (TA) value that the terminal is applying or has applied.

[0252] The terminal transmits the TA value it is applying to the base station. This is to inform the base station of the applied TA value when the terminal applies a TA value without a separate instruction from the base station, or to confirm or determine how the terminal is applying the TA value instructed by the base station. For example, this operation is performed when the satellite to which the terminal is connected is changed, so that the newly connected satellite can confirm the TA value of the terminal. For example, the terminal independently applies a TA value calculated based on the positions of the terminal and the satellite.

[0253] In order for the terminal to report the TA value to the base station, it uses a combination of at least one of the following methods.

[0254] Method 1: The base station uses the DCI to trigger a terminal to report a TA value. The base station triggers a TA value report based on some bit field values ​​or a combination of bit field values ​​in the DCI. A field indicating the triggering of a TA value report is included in the DCI. In this case, when the field in the received DCI is set to a specific value, the terminal understands that a TA value report has been triggered. Alternatively, when the values ​​of one or more fields (e.g., for other purposes) included in the DCI are set to predetermined values, the terminal understands that a TA value report has been triggered. The terminal transmits the TA value at a specific time point based on the time point when the DCI is received to the base station.

[0255] Method 2: The base station triggers the UE to report the TA value using the MAC CE. The base station triggers the UE to report the TA value using a bit value or a bit field value of the MAC CE, and the UE transmits the TA value at the time of receiving the MAC CE or a certain time after the time of receiving the MAC CE to the base station.

[0256] Method 3: The base station uses RRC configuration to instruct the terminal which TA value to report. For example, the base station sets a period and offset value for reporting the TA value or / and specific conditions for the terminal to report the TA value through upper signaling, and determines when the terminal reports the TA value. In this case, the base station also specifies the application time of the reference TA value (i.e., the time when the reported TA value is applied: referred to as the reference time point of the TA value). Here, the specific condition for the terminal to report the TA value is, for example, when the TA value is equal to or greater than a certain value, or when the distance between the terminal and the satellite is equal to or greater than a certain value, and these certain values ​​are set through upper signaling, information transmitted via an SIB, or fixed values.

[0257] Method 4: The terminal reports the TA value without a separate trigger from the base station. For example, in Method 4, the terminal transmits information indicating the TA value to the base station according to a specific condition, and the specific condition is a predetermined condition such as a time for reporting the TA value (without signaling such as DCI, MAC CE, RRC, etc. for a trigger from the base station) or a comparison result between the TA value applied by the terminal and a specific threshold value.

[0258] As described above, when transmitting the TA value, the terminal transmits information of the TA value to the base station using a physical channel such as a PUCCH or a PUSCH or using upper signaling. When the terminal transmits information of the TA value using a physical channel, resources used to report the information of the TA value are configured by upper signaling.

[0259] The reference time for determining the TA value to be reported by the UE and the time at which the UE reports the TA value are determined based on the time at which the UE reports the TA value and the time at which the TA value report is triggered. For example, if a TA value report is triggered by DCI in slot n, the UE reports the TA value applied or calculated in slot nK, and the UE reports the TA value to the base station in slot n+N. Here, K and N are values ​​determined based on the subcarrier spacing or UE capability, the DL / UL configuration of the slot, and the PUCCH resource configuration, respectively. Here, K is 0. K=0 means that the UE reports the TA value based on the time at which a trigger signal for reporting the TA value is received. Here, K is a value smaller than 0. In this case, for example, the UE pre-calculates the TA value at the time at which the UE reports the TA value, generates information to be reported, and reports it. Here, K is an integer value greater than 0. This means that the terminal reports a TA value at an earlier time than the time at which the terminal reports the TA value (e.g., slot n+N). This is because the terminal needs time to encode the information to be reported and prepare for transmission, so it reports the TA value at an earlier time.

[0260] 37A and 37B are diagrams showing an example of the operation of a base station and a terminal for reporting a TA value of a terminal. When reporting a TA value of the present invention, the TA value applied by the terminal is indicated in units of ms, slots, symbols, etc., or is provided as information including decimal points rather than integers. The TA value report of the present invention includes the absolute value of the TA, but also includes a relative TA value or a change in the TA value (for example, the change in the TA value over a certain period of time) excluding the TA value indicated by the previous base station or the predetermined TA value.

[0261] 37A illustrates an example of a base station's operation for reporting a TA value of a terminal. The base station transmits configuration information related to the TA value report through upper layer signaling (step 3700). This configuration information includes at least one of information for configuring the TA value report, such as a period and offset for reporting the TA value, a trigger condition for reporting the TA value, TA value reference time information, the type of TA information to be reported, and resource configuration information for reporting the TA value. The base station triggers the terminal to report the TA value (step 3710). This trigger may be performed, for example, by upper layer signaling or DCI with specific content as described above, but may be omitted. The base station receives a TA value report transmitted by the terminal through the transmitted configuration information (step 3720).

[0262] FIG. 37B illustrates an example of a terminal's operation for reporting a TA value. The terminal receives configuration information related to a TA value report transmitted from a base station using upper signaling (step 3730). The configuration information includes at least one of information for configuring a TA value report, such as a period and offset for reporting the TA value, a trigger condition for reporting the TA value, TA value reference time information, a type of TA information to be reported, and resource configuration information for reporting the TA value. The terminal receives a signal for triggering a TA value report transmitted from the base station (step 3740). This trigger may be performed, for example, by upper signaling or DCI with specific content as described above, but may be omitted. The terminal transmits a TA value report according to the received configuration information (step 3750). For example, if the terminal receives TA value report resource information, it transmits the TA value report using the configured resource. The steps disclosed in FIGS. 37A and 37B may be applied in a different order, and other steps may be added or omitted.

[0263] [Fourth Example]

[0264] The fourth embodiment provides a method and apparatus for a terminal to set the TA value to 0 or a predetermined value.

[0265] If the satellite or base station serving the terminal is suddenly changed, the TA value that the terminal should apply for the next uplink transmission may be suddenly changed. For this reason, a procedure is required to change the TA value applied by the terminal to 0 or a predetermined value. In this case, the TA value is initialized using the following method.

[0266] In the present invention, initializing the TA value means setting the TA value to 0 or to a value previously set by DCI or higher signaling. In the present invention, higher layer signaling refers to signaling transmitted in layers such as MAC, PDCP, and RRC, and is a value that is pre-stored in memory or pre-configured.

[0267] Method 1: Based on the satellite and terminal positions, if the terminal determines that the satellite (or satellites connected to it) serving the terminal has changed, it initializes the TA value. In this case, the terminal reports the TA value it applies to to the base station.

[0268] - Method 2: The base station instructs initialization of the TA value by means of DCI. In this method, the initialization of the TA value is instructed by a specific bit field value or a combination of bit field values ​​in the DCI. For example, a field instructing initialization of the TA value is included in the DCI. In this case, when the field in the received DCI is set to a specific value, the terminal understands that initialization of the TA value has been instructed. Alternatively, when the values ​​of one or more fields (e.g., for other purposes) included in the DCI are set to predetermined values, the terminal understands that initialization of the TA value has been instructed.

[0269] Method 3: If the TA value applied by the terminal exceeds the TA boundary value, the terminal initializes the TA value. The TA boundary value is a value preset by higher layer signaling.

[0270] Although the first to fourth embodiments of the present invention have been described separately above for the sake of convenience, each embodiment includes related operations, and therefore it is possible to combine at least two or more of the embodiments. Furthermore, the methods of each embodiment are not mutually exclusive, and one or more methods may be combined.

[0271] A transmission and reception method between a base station, a satellite, and a terminal, or a transmitting end and a receiving end, for carrying out the above-mentioned embodiments of the present invention is shown, and in order to do this, the receiving unit, processing unit, and transmitting unit of the base station, satellite, and terminal must each operate according to the embodiment.

[0272] Specifically, FIG. 38 is a block diagram showing the internal structure of a terminal according to an embodiment of the present invention. As shown in FIG. 38, the terminal according to this embodiment includes a terminal receiver 3800, a terminal transmitter 3820, and a terminal processor 3810. The terminal receiver 3800 and the terminal transmitter 3820 are collectively referred to as a transceiver in the present embodiment. The transceiver transmits and receives signals to and from a base station. The signals include control information and data. To this end, the transceiver includes an RF transmitter that up-converts and amplifies the frequency of a signal to be transmitted, and an RF receiver that low-noise amplifies and down-converts the frequency of a received signal. The transceiver also receives signals via a wireless channel and outputs them to the terminal processor 3810, and transmits the signals output from the terminal processor 3810 via a wireless channel. The terminal processor 3810 controls a series of processes to operate the terminal according to the above-described embodiment of the present invention. For example, the terminal receiver 3800 receives signals from a satellite or terrestrial base station, and the terminal processor 3810 transmits and receives signals to and from the base station according to the method described herein. Thereafter, the terminal transmitter 3820 transmits a signal using the determined time point.

[0273] FIG. 39 is a block diagram showing the internal structure of a satellite according to an embodiment of the present invention. As shown in FIG. 39, the satellite of the present invention includes a satellite receiving unit 3900, a satellite transmitting unit 3920, and a satellite processing unit 3910. Here, the receiving unit, transmitting unit, and processing unit are configured in plural. That is, each unit includes a receiving unit and a transmitting unit for transmitting and receiving signals from a terminal, and a receiving unit and a transmitting unit for transmitting and receiving signals from a base station (and a receiving unit and a transmitting unit for transmitting and receiving signals with other satellites). The satellite receiving unit 3900 and the satellite transmitting unit 3920 are collectively referred to as the transceiver unit of the satellite in an embodiment of the present invention. The transceiver unit transmits and receives signals to and from a terminal and a base station. The signals include control information and data. To this end, the transceiver unit includes an RF transmitter that up-converts and amplifies the frequency of a signal to be transmitted, an RF receiver that low-noise amplifies the received signal, and down-converts the frequency. In addition, the transceiver unit receives signals via a wireless channel and outputs them to the satellite processing unit 3910, and transmits the signals output from the satellite processing unit 3910 via a wireless channel. The satellite processing unit 3910 includes a compensator (pre-compensator) for correcting frequency offset or Doppler shift, and a device for tracking location using GPS, etc. The satellite processing unit 3910 also includes a frequency shift function for shifting the center frequency of the received signal. The satellite processing unit 3910 controls a series of processes so that the satellite, base station, and terminal operate according to the above-described embodiment of the present invention. For example, the satellite receiving unit 3900 receives a PRACH preamble from the terminal, and determines to transmit a corresponding RAR to the terminal and transmit TA information to the base station. The satellite transmitting unit 3920 then transmits the signal at the determined time.

[0274] FIG. 40 is a block diagram showing the internal structure of a base station according to an embodiment of the present invention. As shown in FIG. 40, the base station according to the present invention includes a base station receiver 4000, a base station transmitter 4020, and a base station processor 4010. The base station is a part of a terrestrial base station or a satellite. The base station receiver 4000 and the base station transmitter 4020 are collectively referred to as a transceiver in the present embodiment. The transceiver transmits and receives signals to and from a mobile station. The signals include control information and data. To this end, the transceiver comprises an RF transmitter that up-converts and amplifies the frequency of a signal to be transmitted, and an RF receiver that low-noise amplifies and down-converts the frequency of a received signal. The transceiver also receives signals via a wireless channel and outputs them to the base station processor 4010, and transmits the signals output from the base station processor 4010 via a wireless channel. The base station processor 4010 controls a series of processes to operate the base station according to the above-described embodiment of the present invention. For example, the base station processor 4010 transmits an RAR including TA information.

[0275] As an example, a method for executing a terminal in a communication system includes the steps of receiving downlink control information including first timing advance (TA) loop index information from a base station, determining a first TA value corresponding to the first TA loop index determined based on the first TA loop index information, and applying the first TA value to transmit uplink data based on the downlink control information, wherein the downlink control information further includes uplink data scheduling information.

[0276] In addition, a method for executing a base station in a communication system includes a step of transmitting downlink control information including first timing advance (TA) loop index information to a terminal, and a step of receiving uplink data according to the downlink control information, wherein a TA value serving as a base for uplink data transmission is a first TA value corresponding to a first TA loop index confirmed based on the first TA loop index information, and the downlink control information further includes uplink data scheduling information.

[0277] In addition, a terminal in the communication system includes a transceiver unit and a controller, and the controller receives downlink control information including first timing advance (TA) loop index information from a base station, identifies a first TA value corresponding to the first TA loop index identified based on the first TA loop index information, and controls to transmit uplink data based on the downlink control information by applying the first TA value, and the downlink control information further includes uplink data scheduling information.

[0278] In addition, the base station in the communication system includes a transceiver unit and a controller, and the controller transmits downlink control information including first timing advance (TA) loop index information to the terminal and further controls the terminal to receive uplink data according to the downlink control information, and the TA value serving as a base for uplink data transmission is a first TA value corresponding to a first TA loop index confirmed based on the first TA loop index information, and the downlink control information further includes uplink data scheduling information.

[0279] Meanwhile, the embodiments of the present invention disclosed in this specification and drawings merely present specific examples to easily explain the technical content of the present invention and to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention. That is, it will be apparent to those skilled in the art that other modifications based on the technical concept of the present invention are possible. Furthermore, the above-described embodiments may be combined with each other as necessary. Furthermore, the above-described embodiments may be implemented in LTE systems, 5G systems, and the like, based on the technical concept of the above-described embodiments. [Explanation of symbols]

[0280] 102 OFDM symbols 104, 110 subcarriers 106 Slots 108 Resource Blocks (RB) or PRBs 112 Resource Element (RE) 114 Radio Frame 201, 202 Control Area #1, #2 203 Frequency Resources 204 Control Region Length 210 Terminal Bandwidth Portion 220 Slots 300 System-wide frequency band 301, 408 eMBB 303, 305, 307 URLLC data 309 mMTC 402, 404, 406 sub-bands 410, 412, 414 URLLC 416 mMTC 501 Transfer Blocks (TB) 503, 517, 519, 521, 523 CRC 507, 509, 511, 513 Code Block (CB) 1, 2, N-1, N 601 Main synchronization signal (PSS) 603 Sub-synchronization signal (SSS) 802, 804 slot n 806, 808 slot n+4 810 Propagation delay time (Tp) 812 Timing Advance (TA) 900TB1 902 Slot 0 904 ACK / NACK Feedback 906 Slot 4 908 Slot 8 910 Resend 1001, 1210, 3210, 3310, 3400 terminals 1003, 1200 satellites 1005 Base station 1100 Geostationary orbit satellite (GEO) 1110 Medium orbit satellite (MEO) 1130 Low Earth Orbit Satellite (LEO) 1220, 3240 ground station 1230 base station (DU farms) 1600, 1610, 1620 Path Loss 1900, 1910 Terminal 1, 2 2100 Delay time from terminal to satellite 2110 Round-trip delay time between terminal, satellite and base station 2300 Random Access Response (RAR) Information about 2310 TA values 2320 Temporary C-RNTI value Send 2400, 2500 PRACH 2410, 2510 random access window Received 2420 and 2520 RAR 2700 Solar panels or solar arrays 2710 Transmitting and receiving antenna for communication with terminal 2720 ​​Transmitting and receiving antennas for communication with ground stations 2730 Transmitting and receiving antenna for inter-satellite communications 3100 Same MAC CE 3110, 3112, 3114, 3116, 3118, 3120, 3122, 3124, 3126 One group of terminals 3130 Start position of time offset indicator 3220, 3320, 3410 Satellite 1 3230, 3330, 3420 Satellite 2 3340, 3350 Ground Station 1, 2 3412, 3422 TA Loop 1, 2 3800 Terminal receiver 3810 Terminal processing unit 3820 Terminal transmitter 3900 Satellite receiver 3910 Satellite Processing Unit 3920 Satellite Transmitter 4000 Base Station Receiver 4010 Base station processing unit 4020 Base station transmitter

Claims

1. A method performed by a terminal in a communication system, comprising: receiving configuration information for non-terrestrial network communication from a base station; checking a timing advance (TA) value; transmitting an uplink signal to the base station by applying the TA value; determining whether the TA report is triggered based on a threshold value for the TA report; transmitting the TA report to the base station via a MAC medium access control element (CE); The TA report includes the value of the TA calculated by the terminal; The method, wherein the value of the TA relates to a first offset commonly applied to multiple terminals and a second offset for the terminal.

2. 2. The method of claim 1, wherein the first offset is based on an indication of a rate of change of the TA and the second offset is based on higher layer signaling.

3. The value of the TA included in the TA report is determined based on a time point of the TA report; The method of claim 1 , wherein the TA value included in the TA report is indicated in slot units.

4. The method of claim 1, wherein the threshold value for the TA report is set as higher layer signaling.

5. 1. A method performed by a base station in a communication system, comprising: transmitting setting information related to non-terrestrial network communication to the terminal; receiving an uplink signal to which a timing advance (TA) value is applied from the terminal; receiving a TA report from the terminal via a MAC medium access control element (CE); The TA report is triggered based on a threshold value for the TA report; The TA report includes the value of the TA calculated by the terminal; The method, wherein the value of the TA relates to a first offset commonly applied to multiple terminals and a second offset for the terminal.

6. 6. The method of claim 5, wherein the first offset is based on an indication of a rate of change of the TA and the second offset is based on higher layer signaling.

7. The value of the TA included in the TA report is determined based on a time point of the TA report; The method of claim 5 , wherein the TA value included in the TA report is indicated in slot units.

8. The method of claim 5, wherein the threshold value for the TA report is transmitted via higher layer signaling.

9. A terminal in a communication system, a transmitter / receiver; a control unit coupled to the transceiver unit, The control unit receiving setting information related to non-terrestrial network communication from a base station; Check the timing advance (TA) value, Applying the TA value to the base station to transmit an uplink signal; determining whether the TA report is triggered based on a threshold value for the TA report; Controlling the base station to transmit the TA report via a MAC medium access control element (CE); The TA report includes the value of the TA calculated by the terminal; The terminal, wherein the TA value relates to a first offset commonly applied to multiple terminals and a second offset for the terminal.

10. 10. The terminal of claim 9, wherein the first offset is based on an indication of a rate of change of the TA, and the second offset is based on higher layer signaling.

11. The value of the TA included in the TA report is determined based on a time point of the TA report; The terminal of claim 9, wherein the TA value included in the TA report is indicated in slot units.

12. The terminal of claim 9, wherein the threshold value for the TA report is set as higher layer signaling.

13. A base station in a communication system, comprising: a transmitter / receiver; a control unit coupled to the transceiver unit, The control unit Transmitting setting information regarding satellite network (non-terrestrial network) communication to the terminal; receiving an uplink signal to which a timing advance (TA) value is applied from the terminal; Controlling the terminal to receive a TA report via a MAC medium access control element (CE); The TA report is triggered based on a threshold value for the TA report; The TA report includes the value of the TA calculated by the terminal; The base station, wherein the TA value relates to a first offset commonly applied to a plurality of terminals and a second offset for the terminal.

14. The base station of claim 13, wherein the first offset is based on an indication of a rate of change of the TA, and the second offset is based on higher layer signaling.

15. The value of the TA included in the TA report is determined based on a time point of the TA report; The base station of claim 13, wherein the TA value included in the TA report is indicated in slot units.

16. The base station of claim 13, wherein the threshold value for the TA report is transmitted via higher layer signaling.

Images