Transmission method and device of delay-doppler-time coding-based OTFS system for improving diversity gain

Abstract

A disclosed embodiment provides a transmission device of an OTFS system capable of maximizing the diversity gain, which makes it possible that coded symbols are transmitted through various transmission channels of a delay-Doppler (DD) domain effective channel by including the steps of: dividing an information symbol vector including L x M x N symbols into L hierarchical information symbol vectors, and acquiring L spread signal vectors by spread-coding each of the L hierarchical information symbol vectors; dividing each of the L unit signal vectors into L unit spread vectors to map same to L time intervals, and acquiring a coded signal vector including the L unit spread vectors mapped to the L time intervals; and acquiring L DD signal matrices by distributed-mapping, in a diagonal cyclic structure, each of the acquired L coded signal vectors to a DD domain including M delay time grids and N Doppler grids.

Description

Transmission method and apparatus of a delay-Doppler-time coding-based OTFS system for diversity gain enhancement

[0001] The disclosed embodiments relate to a transmission method and apparatus of an OTFS system, and more specifically to a transmission method and apparatus of a delay-Doppler-time coding-based OTFS system for diversity gain enhancement.

[0002] In next-generation communication environments, scenarios regarding high-speed time-varying channels—that is, channels where a high Doppler effect is induced—must be considered due to the rapid mobility of terminals. However, existing Orthogonal Frequency Division Multiplexing (OFDM) systems suffer from degraded error performance in high-speed time-varying channels. Therefore, to improve the performance of OFDM in high-speed time-varying channels, Orthogonal Time Frequency Space (OTFS) systems have been studied. OTFS systems achieve lower error performance compared to OFDM in high-speed time-varying channels by introducing a Delay-Doppler (DD) domain.

[0003] In addition, a phase rotation technique in the delay-Doppler domain has been proposed to improve diversity gain in the OTFS system. However, conventional phase rotation techniques consider only a single time interval. Existing phase rotation techniques that consider a single time interval rotate the phase of each information symbol in the DD domain, but since there is no process of spreading the information symbols, a single information symbol cannot be transmitted over multiple time intervals, and thus there is a limitation in that sufficient diversity gain cannot be secured even when applying space-time coding techniques.

[0004] The disclosed embodiments aim to provide a transmission method and apparatus capable of maximizing diversity gain by allowing encoded symbols to be transmitted through various transmission channels of a DD domain effective channel.

[0005] The disclosed embodiments aim to provide a transmission method and apparatus that spread information symbols by considering multiple time intervals and encode the spread signal by mapping it to a diagonal cyclic structure for the DD domain.

[0006] A transmission method according to an embodiment comprises the steps of: dividing an information symbol vector composed of L × M × N symbols into L layered information symbol vectors, and spreading-coding each of the L layered information symbol vectors to obtain L spread signal vectors; dividing each of the L spread signal vectors into L unit spread vectors and mapping them to L time intervals, and obtaining an encoded signal vector composed of L unit spread vectors mapped to L time intervals; and dispersing each of the obtained L encoded signal vectors into a delay-Doppler (hereinafter DD) domain composed of M delay time grids and N Doppler grids in a diagonal cyclic structure to obtain L DD signal matrices.

[0007] The step of obtaining the above DD signal matrix can be to divide the L encoded signal vectors, each having a size of MN×1, into N unit encoded signal vectors, each having a size of M×1, and to obtain the L DD signal matrices by weighting a permutation matrix of order according to the position in the Doppler axis direction to a diagonal matrix in which the divided N unit encoded signal vectors are arranged diagonally.

[0008] The above permutation matrix can be composed of a matrix in which each row of an M×M identity matrix is ​​rotated one row at a time to form a diagonal rotational structure starting from the second row.

[0009] The step of obtaining the above-mentioned encoded signal vector can be achieved by dividing each of the L spreading signal vectors into L unit spreading vectors, sequentially mapping the L unit spreading vectors divided from each spreading signal vector to L time intervals, and selecting and extracting one unit spreading vector from each time interval from the L unit spreading vectors mapped to the L time intervals to obtain the encoded signal vector.

[0010] The above encoded signal vector can be obtained by extracting unit diffusion vectors that are cyclically arranged diagonally based on the unit diffusion vector mapped from each time interval among L unit diffusion vectors mapped to each of L time intervals.

[0011] The above L spread signal vectors can be obtained by spreading the L layer information symbol vectors respectively according to the spreading coding technique used in the FDFR method of the MIMO system.

[0012] The above information symbol vector can be obtained by converting the L×M×N symbols, which are obtained by digitally modulating the data of L OTFS frames to be transmitted during L time intervals, into a vector of size LMN×1.

[0013] A transmitting device according to an embodiment is a device having one or more processors; and a memory for storing one or more programs executed by the one or more processors, wherein the processor performs the steps of: dividing an information symbol vector composed of L × M × N symbols into L hierarchical information symbol vectors, and spreading-coding each of the L hierarchical information symbol vectors to obtain L spread signal vectors; dividing each of the L spread signal vectors into L unit spread vectors and mapping them to L time intervals, and obtaining an encoded signal vector composed of L unit spread vectors mapped to L time intervals; and distributing each of the obtained L encoded signal vectors into a delay-Doppler (hereinafter DD) domain composed of M delay time grids and N Doppler grids in a diagonal cyclic structure to obtain L DD signal matrices.

[0014] Accordingly, the transmission method and device according to the embodiment can maximize diversity gain by spreading information symbols by considering multiple time intervals and encoding the spread signal by mapping it to a diagonal cyclic structure with respect to the DD domain, thereby allowing the encoded symbols to be transmitted through various transmission channels of the DD domain effective channel. Therefore, communication efficiency can be improved in various fields that consider high-speed time-varying channels, such as low-orbit satellites, drone and aviation communication, autonomous vehicles, high-speed railways, vehicle-to-vehicle communication, and vehicle-to-infrastructure communication, and it can be easily applied to existing communication infrastructure by having high compatibility with OFDM systems.

[0015] Figure 1 shows a configuration in which a transmitting device of an OTFS system according to one embodiment is classified according to operation.

[0016] Figure 2 is a diagram illustrating the delay-Doppler-time encoding process of the transmitting device of Figure 1.

[0017] FIG. 3 illustrates a transmission method of an OTFS system according to one embodiment.

[0018] Figure 4 shows the results of simulating the performance of an OTFS system to which the transmission method of one embodiment is applied.

[0019] FIG. 5 is a diagram illustrating a computing environment including a computing device according to one embodiment.

[0020] Hereinafter, a specific embodiment of one embodiment will be described with reference to the drawings. The following detailed description is provided to facilitate a comprehensive understanding of the methods, devices, and / or systems described herein. However, this is merely illustrative and the invention is not limited thereto.

[0021] In describing the embodiments, if it is determined that a detailed description of known technology related to the present invention might unnecessarily obscure the essence of the embodiment, such detailed description will be omitted. Furthermore, the terms described below are defined with consideration of their functions in the present invention, and these may vary depending on the intentions or practices of the user or operator. Therefore, such definitions should be based on the content throughout this specification. Terms used in the detailed description are intended merely to describe the embodiments and should not be limiting. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form. In this description, expressions such as “include” or “compose” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts thereof, or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts thereof, or combinations thereof other than those described. Additionally, terms such as “...part,” “...unit,” “module,” and “block” described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0022] FIG. 1 shows a configuration in which a transmitting device of an OTFS system according to one embodiment is classified according to operation, and FIG. 2 is a diagram for explaining the delay-Doppler-time encoding process of the transmitting device of FIG. 1.

[0023] Referring to FIG. 1, the transmitting device of an OTFS system of one embodiment includes a parameter setting module (11), a symbol modulation module (12), a spreading coding module (13), a time coding module (14), a DD coding module (15), and an OFDM modulation module (16).

[0024] First, the parameter setting module (11) sets encoding parameters (L, M, N) for encoding symbols to be transmitted by the transmitting device. Here, the encoding parameters (L, M, N) may include the number of time intervals (L), the number of delay grids (M), and the number of Doppler grids (N). The number of time intervals (L) can be set according to the number of OTFS frames to be transmitted, and the number of delay grids (M) and the number of Doppler grids (N) represent the number of delay grids and the number of Doppler grids in which symbols can be distinguished and mapped in the Delay-Doppler (DD) domain to express the delay and Doppler effects induced in the signal by the channel. In addition, M and N in the DD domain are mapped to the number of frequency grids and the number of time grids in the Time-Frequency (TF) domain of the OFDM system, respectively, to represent the number of subcarrier indices and the number of time indices per frequency.

[0025] However, in one embodiment, it is assumed that the number of time intervals (L) is less than or equal to the number of delayed grids (M) and the number of Doppler grids (N) (L < M,N), and that the number of delayed grids (M) and the number of Doppler grids (N) are the same (M = N).

[0026] The symbol modulation module (12) performs digital modulation on the data of L frames to be transmitted according to the encoding parameters (L, M, N) set in the parameter setting module (11) to generate L×M×N modulated symbols. Then, for the convenience of subsequent encoding, the symbol modulation module (12) may organize the generated L×M×N symbols into an information symbol vector (x) of size LMN×1.

[0027] The spreading coding module (13) obtains an LMN×1 size information symbol vector (x) from the symbol modulation module (12) and L layer information symbol vectors (x1, x2, …, x) each having a size of MN×1. L It is distinguished by ). That is, the information symbol vector (x) is distinguished as in Equation 1, and L hierarchical information symbol vectors (x1, x2, …, x L It can be divided into ).

[0028]

[0029] The diffusion encoding module (13) is L layered information symbol vectors (x1, x2, …, x) separated from the information symbol vector (x). L Each is granted a ) and for each layer, L pre-set diffusion matrices of size MN × MN (θ1, θ2, …, θ L Using ) each layer information symbol vector(x k By spreading and encoding , k ∈ {1, 2, … , L}), a spread signal vector of size MN×1 (u k = θ k x k Acquires ).

[0030] Spread coding is a technique used in existing MIMO (Multiple Input Multiple Output) systems. In MIMO systems, Space-Time Code (STC) methods using spread coding are applied to increase diversity, and BLAST (Bell Labs Layered Spaced Time Architecture) methods are applied to increase data transmission capacity. Currently, Full Diversity Full Rate (FDFR) coding methods are mainly utilized to achieve maximum diversity gain while achieving maximum transmission efficiency by combining the advantages of STC and BLAST methods.

[0031] In this FDFR method, information symbols are spread-coded to obtain a spread signal, and the obtained spread signal is mapped and transmitted across multiple transmitting antennas of the MIMO system over multiple time intervals. Thus, a single encoded information symbol is transmitted and received through the transmission channel over the time intervals spread through all transmitting and receiving antennas, thereby extending the diversity effect in the time domain to the space domain, which enables a lower error rate to be achieved.

[0032] A diffusion encoding module (13) of one embodiment has a diffusion matrix (θ) for each layer (k) according to the diffusion encoding technique used in the FDFR method of a conventional MIMO system. k ) can be set as in mathematical formula 2.

[0033]

[0034] Here, F MN is an M×N Discrete Fourier Transform (DFT) matrix, and (·) Hrepresents the conjugate transpose, diag(·) represents an MN×MN diagonal matrix, α is a factor set to distinguish information symbols within each layer (k), and β is a factor set to distinguish between layers.

[0035] And the diffusion matrix (θ set for each layer according to mathematical formula 2) k ) as in Equation 3, the hierarchical information symbol vector(x k Diffusion encoding by multiplying by ) to create a diffuse signal vector of size MN×1 (u k Acquires ).

[0036]

[0037] Here, the layer information symbol vector (x k Since there are L , k ∈ {1, … , L}), the diffusion encoding module (13) has L diffusion signal vectors (u k You can obtain ).

[0038] The time encoding module (14) obtains L spread signal vectors (u) from the spread encoding module (13). k ) is applied, and the applied L diffusion signal vectors (u k Each of these again into L unit diffusion vectors (u k (1) , u k (2) , … , u k (L) It is divided by ) here. Here, the diffusion signal vector (u k ) is separated as in Equation 4, with L unit diffusion vectors (u k (1) , u k (2) , … , u k (L) It can be divided into ).

[0039]

[0040] Here, the diffusion signal vector of the k-th layer (u k L unit diffusion vectors (u) split from )k (1) , u k (2) , … , u k (L) ) among the l-th unit diffusion vector(u k (l) )Is or It can have the size of. and represents the ceiling function and floor function, respectively.

[0041] And the time encoding module (14) is divided into L unit diffusion vectors (u k (1) , u k (2) , … , u k (L) ) is mapped to L time intervals respectively.

[0042] As mentioned above, spreading coding is a technique for transmitting symbols by mapping them across multiple transmitting antennas in a conventional MIMO system. However, unlike a MIMO system, the OTFS system of one embodiment does not use multiple transmitting antennas. Accordingly, the time coding module (14) obtains a spread signal vector (u) for each layer (k). k L unit diffusion vectors (u) separated in each k (1) , u k (2) , … , u k (L) ) is mapped to L time intervals in a distributed manner.

[0043] L diffusion signal vectors (u) obtained for each layer (k) k ) again L unit diffusion vectors (u k (1) , u k (2) , … , u k (L)It is divided into ) and sequentially mapped to L time intervals, so each of the L time intervals has L different diffuse signal vectors (u k L unit diffusion vectors that are split and mapped in ) are mapped redundantly.

[0044] Accordingly, the time encoding module (14) selects and extracts one unit diffusion vector from each time interval (l) among the unit diffusion vectors mapped to L time intervals, thereby encoding the signal vector (c l ) is obtained. In particular, as in Equation 5, among the unit diffusion vectors mapped in groups of L, the unit diffusion vector (u) mapped from each time interval (l) l (1) An encoded signal vector of size MN×1 (c) consisting of unit diffusion vectors cyclically arranged diagonally based on ) l You can obtain ).

[0045]

[0046] Here [] L represents a modular operator of size L.

[0047] Since the number of time intervals is L, the time encoding module (14) has L encoded signal vectors (c l ) can be obtained, and each encoded signal vector (c l As shown in Equation 5, ) includes all information from L layers. Therefore, each encoded signal vector (c l It can be seen that ) contains all LMN information symbols of the information symbol vector (x).

[0048] The DD encoding module (15) has L encoded signal vectors of size MN×1 obtained from the time encoding module (14) (c l ) is received, and each is mapped to the DD domain to form L DD signal matrices (X DD (l) ) is obtained. At this time, the encoded signal vector (c lDepending on how ) is mapped to the DD domain, the DD domain valid channels of the OTFS system can affect diversity.

[0049] As mentioned above, each encoded signal vector (c l ) contains all LMN information symbols of the information symbol vector (x). Therefore, the encoded signal vector (c l When ) is mapped to the DD domain and transmitted, the receiving device extracts and restores the information symbol vector (x) transmitted mapped to the DD domain. At this time, the encoded signal vector (c l If ) is simply mapped only in the direction of the delay axis or the Doppler axis of the 2D DD domain, only a portion of the information symbol vector (x) that is mapped to the DD domain and transmitted in segments is acquired, rather than the whole, resulting in a channel where the information symbol vector (x) cannot be reconstructed. Furthermore, even if the entire segmented mapped information symbol vector (x) is transmitted and the information symbol vector (x) can be reconstructed, it may result in information symbol vectors (x) that are segmented and transmitted differently passing through the same channel. In other words, it may result in duplicate transmission on the same channel. As such, if the information symbol vector (x) is transmitted only partially or the number of channels with duplicate transmission increases, diversity decreases. And the encoded signal vector (c l Even when mapping ) to the diagonal matrix direction of the 2D DD domain, it results in a decrease in diversity.

[0050] Accordingly, the DD encoding module (15) of one embodiment is an encoded signal vector (c l By mapping ) to the 2D DD domain according to Equation 6 and encoding, the DD signal matrix (X DD (l) Acquires ).

[0051]

[0052] Here Π Mis a permutation matrix obtained by rotating each row of an M×M identity matrix by one row, am.

[0053] According to mathematical formula 6, the DD encoding module (15) has an encoded signal vector of size MN×1 (c l ) N unit encoded signal vectors (c) each having a size of M×1 l (1), … , c l (N)) separated into N unit encoded signal vectors (c l (1), … , c l (N)) obtains a diagonal matrix in which the diagonals are arranged, and unit encoding signal vectors (c) arranged in the obtained diagonal matrix l (1), … , c l (N)) A permutation matrix of order according to each Doppler axis position (n) (Π M The DD signal matrix (X) for the l-th time interval is obtained by weighted summing ) DD (l) Obtain ). DD signal matrix(X DD (l) ) has a size of M×N.

[0054] That is, the DD encoding module (15) is an encoded signal vector (c l Map ) into a diagonal cyclic structure, but map it into a diagonal cyclic structure starting from the 2nd row so as to form the DD signal matrix (X DD (l) Acquires ).

[0055] The DD encoding module (15) has an encoded signal vector (c) for each time interval (l ∈ {1, …, L}). l ) is mapped to the DD domain, and L DD signal matrices of size M×N (X DD (l) When ) is obtained, the obtained DD signal matrix (X DD (l) ) is transmitted to the OFDM modulation module (16).

[0056] The OFDM modulation module (16) obtains a DD signal matrix (X) for each time interval (l). DD (l) ) transmit signal vector(s) according to the OFDM technique (l) ) modulates with ). The OFDM modulation module (16) first modulates L DD signal matrices (X) obtained from the DD encoding module (15). DD (l) For each of ), the Inverse Symplectic Finite Fourier Transform (ISFFT) is performed to convert it into a TF signal in the time-frequency (TF) domain. Subsequently, the converted TF signal is OFDM modulated to obtain the transmitted signal vector (s) of the l-th time interval (l). (l) Converts to ).

[0057] The OFDM modulation module (16) is a DD signal matrix (X) according to Equation 7. DD (l) ) is a transmitted signal vector of size MN×1 (s (l) It can be converted to ).

[0058]

[0059] Here x DD (l) is an M×N DD signal matrix (X DD (l) It is a DD signal vector converted to an MN×1 size, and I M is an M×M identity matrix, and F N is an N×N discrete Fourier transform matrix, and (·) H represents the conjugate transposition, represents the Kronecker product operator.

[0060] Transmission signal vector(s) obtained from the OFDM modulation module (16) (l) ) is transmitted to a receiving device (not shown) via a multipath channel during the lth time interval.

[0061] The receiving device has L transmission signal vectors (s) from the transmitting device. (l) If ) is transmitted over L time intervals, L received signal vectors (r (l) ) is received and obtained, and the received L received signal vectors (r (l) Perform OTFS demodulation on ) to DD signal matrix (X DD (l) The received signal matrix (Y) of the DD domain corresponding to ) DD (l) ) is obtained, and the received signal matrix (Y) of L DD domains obtained over L time intervals is obtained. DD (l) Detects the information symbol vector (x) transmitted through ).

[0062] Since OFDM modulation and OTFS demodulation techniques are known technologies, a detailed explanation is omitted here.

[0063] Consequently, the transmitting device of an OTFS system of one embodiment performs spreading coding on an information symbol vector (x) obtained by digitally modulating the data of L OTFS frames to be transmitted, and spreads it into L layers consisting of a number equal to the number of OTFS frames (L), thereby creating L spread signal vectors (u k ) obtain . and L diffusion signal vectors (u k Each of these again into L unit diffusion vectors (u k (1) , u k (2) , … , u k (L) Divided by ), and each diffusion signal vector (u) through time encoding k L unit diffusion vectors (u) split from ) k (1) , u k (2) , … , u k (L)) is distributed and mapped to L time intervals respectively, and among the L unit diffusion vectors mapped to each of the L time intervals, the unit diffusion vector (u) mapped from each time interval (l) l (1) An encoded signal vector (c) composed of unit diffusion vectors cyclically arranged diagonally based on ) l ) is obtained. Subsequently, the encoded signal vector (c) for each time interval (l) is obtained. l Mapping ) into a diagonal cyclic structure in the DD domain to L DD signal matrices (X DD (l) Acquires ), and the acquired DD signal matrix (X DD (l) ) Each of the transmitted signal vectors (s) according to the OFDM technique (l) Modulate with ), and the modulated transmitted signal vector(s (l) Transmits ) to the receiving device.

[0064] By mapping a diagonal circular structure, encoded information symbols can be transmitted to a receiving device via various different transmission channels for the effective channel in the delay-Doppler domain of the OTFS system, thereby enhancing diversity. Consequently, communication efficiency can be improved in various fields that consider high-speed time-varying channels, such as low-orbit satellites, drone and aviation communications, autonomous vehicles, high-speed railways, vehicle-to-vehicle communication, and vehicle-to-infrastructure communication. Furthermore, it offers high compatibility with OFDM systems, allowing for easy application to existing communication infrastructure.

[0065] In the illustrated embodiments, each component may have different functions and capabilities other than those described below, and may include additional components other than those not described below. Additionally, in one embodiment, each component may be implemented using one or more physically separated devices, or by one or more processors or a combination of one or more processors and software, and may not be clearly distinguished in specific operation as in the illustrated examples.

[0066] And the transmitting device illustrated in FIG. 1 may be implemented in a logic circuit by hardware, firmware, software, or a combination thereof, or may be implemented using a general-purpose or specific-purpose computer. The device may be implemented using a hardwired device, a field programmable gate array (FPGA), an application-specific integrated circuit (ASIC), etc. Additionally, the device may be implemented as a system on chip (SoC) including one or more processors and controllers.

[0067] In addition, the transmitting device may be mounted on a computing device or server equipped with hardware elements in the form of software, hardware, or a combination thereof. A computing device or server may refer to various devices that include, in whole or in part, communication devices such as communication modems for communicating with various devices or wired / wireless communication networks, memory for storing data for executing programs, and microprocessors for executing programs to perform calculations and commands.

[0068] FIG. 3 illustrates a transmission method of an OTFS system according to one embodiment.

[0069] Referring to FIG. 3, a transmission method according to an actual embodiment first receives data of L OTFS frames to be transmitted, digitally modulates them to generate symbols, and combines the generated symbols to obtain an information symbol vector (x) (31). At this time, L×M×N symbols are generated for subsequent mapping to the DD domain, and the information symbol vector (x) can be obtained with an LMN×1 size.

[0070] When an information symbol vector (x) is obtained, an information symbol vector (x) of size LMN×1 is used as L layer information symbol vectors (x1, x2, …, x LDivided by ), and L divided layer information symbol vectors (x1, x2, …, x L By spreading ) and spreading it to L layers, which are equal in number to the number of OTFS frames (L), the spread signal vector (u) for each of the L layers k ) is obtained (32). Here, spreading coding can be performed according to the FDFR technique of the existing MIMO system.

[0071] And L diffusion signal vectors (u) obtained for each of the L layers k Each of L unit diffusion vectors (u k (1) , u k (2) , … , u k (L) Divided by ), and each diffusion signal vector (u k Unit diffusion vector (u) divided into L parts in ) k (1) , u k (2) , … , u k (L) ) is distributed and mapped to L time intervals (33).

[0072] L diffuse signal vectors (u k L unit diffusion vectors (u) split from each k (1) , u k (2) , … , u k (L) If ) is distributed and mapped across L time intervals, one unit diffusion vector is selected and extracted from each time interval (l) among the L unit diffusion vectors mapped to each of the L time intervals to form an encoded signal vector (c l ) is obtained (34). At this time, the unit diffusion vectors cyclically arranged diagonally from the unit diffusion vectors mapped to L time intervals are extracted to obtain the encoded signal vector (c l Acquires ).

[0073] And the acquired L encoded signal vectors (c l Each is distributedly mapped in a diagonal cyclic structure to a DD domain consisting of M delay time grids separated along the delay time axis and N Doppler grids separated along the Doppler axis to form L DD signal matrices (X DD (l) ) is obtained (35). At this time, the encoded signal vector (c l ) is L encoded signal vectors (c) depending on the number of Doppler gratings (N) among the number of delay gratings (M) and the number of Doppler gratings (N) of the DD domain. l Each of the N unit encoded signal vectors (c l (1), … , c l (N)) separated into N unit encoded signal vectors (c l (1), … , c l (N)) is a diagonal matrix in which the order of the permutation matrix (Π) according to the position (n) in the Doppler axis direction is arranged diagonally. M Weighted sum of ) to DD signal matrix(X DD (l) ) can be obtained. Here, the permutation matrix (Π M ) is a matrix formed by rotating each row of an M×M identity matrix by one row.

[0074] Subsequently, the acquired DD signal matrix (X DD (l) ) Each of the transmitted signal vectors (s) according to the OFDM technique (l) Modulate with ), and the modulated transmitted signal vector(s (l) ) is transmitted to the receiving device (36).

[0075] Although FIG. 3 describes each process as being executed sequentially, this is merely an illustrative description, and a person skilled in the art can apply various modifications and variations by changing the order described in FIG. 5, executing one or more processes in parallel, or adding other processes, within the scope of not departing from the essential characteristics of the embodiment of the present invention.

[0076] Figure 4 shows the results of simulating the performance of an OTFS system to which the transmission method of one embodiment is applied.

[0077] In Figure 4, performance was analyzed based on the Bit Error Rate (BER). For comparative evaluation, the existing OTFS system, the phase rotation technique-based OTFS system, and the OTFS system with the STC (space time code) technique applied were compared with the OTFS system with the transmission method of one embodiment applied. In Figure 4, the OTFS system with the STC technique applied is also a new system that has not been previously proposed, just like the OTFS system with the transmission method of one embodiment applied, and it can be seen that it exhibits superior performance compared to the existing OTFS system and the phase rotation technique-based OTFS system. However, it can be seen that the OTFS system with the transmission method of one embodiment exhibits even superior performance by further improving diversity through diagonal circular structure mapping during the DD encoding process.

[0078] FIG. 5 is a diagram illustrating a computing environment including a computing device according to one embodiment.

[0079] In the illustrated embodiments, each component may have different functions and capabilities in addition to those described below, and may include additional components in addition to those not described below. The illustrated computing environment (50) may include a computing device (51) to perform the transmission method illustrated in FIG. 3. In one embodiment, the computing device (51) may be one or more components included in the transmission device illustrated in FIG. 1.

[0080] A computing device (51) includes at least one processor (52), a computer-readable storage medium (53), and a communication bus (55). The processor (52) may enable the computing device (51) to operate according to the exemplary embodiment described above. For example, the processor (52) may execute one or more programs (54) stored in the computer-readable storage medium (53). The one or more programs (54) may include one or more computer-executable instructions, and the computer-executable instructions may be configured to enable the computing device (51) to perform operations according to the exemplary embodiment when executed by the processor (52).

[0081] The communication bus (55) interconnects various other components of the computing device (51), including the processor (52) and the computer-readable storage medium (53).

[0082] The computing device (51) may also include one or more input / output interfaces (56) and one or more communication interfaces (57) that provide an interface for one or more input / output devices (58). The input / output interfaces (56) and the communication interfaces (57) are connected to a communication bus (55). The input / output devices (58) may be connected to other components of the computing device (51) through the input / output interfaces (56). An exemplary input / output device (58) may include input devices such as a pointing device (such as a mouse or trackpad), a keyboard, a touch input device (such as a touchpad or touchscreen), a voice or sound input device, various types of sensor devices and / or imaging devices, and / or output devices such as a display device, a printer, a speaker and / or a network card. An exemplary input / output device (58) may be included inside the computing device (51) as a component constituting the computing device (51), or it may be connected to the computing device (51) as a separate device distinct from the computing device (51).

[0083] Although the present invention has been described in detail above through representative embodiments, those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. A step of dividing an information symbol vector composed of L × M × N symbols into L layered information symbol vectors, and spreading-coding each of the L layered information symbol vectors to obtain L spread signal vectors; A step of dividing each of the above L diffusion signal vectors into L unit diffusion vectors and mapping them to L time intervals, and obtaining an encoded signal vector composed of L unit diffusion vectors mapped to L time intervals; and A transmission method of an OTFS system comprising the step of obtaining L DD signal matrices by distributing each of the obtained L encoded signal vectors into a delay-Doppler (hereinafter DD) domain consisting of M delay time grids and N Doppler grids in a diagonal cyclic structure.

2. In claim 1, the step of acquiring the DD signal matrix The above L encoded signal vectors, each having a size of MN×1, are divided into N unit encoded signal vectors, each having a size of M×1, and A transmission method of an OTFS system for obtaining L DD signal matrices by weighting a permutation matrix of order according to the position in the Doppler axis direction to a diagonal matrix in which the N separated unit encoded signal vectors are arranged diagonally.

3. In paragraph 2, the above permutation matrix is A transmission method for an OTFS system in which each row of an M×M identity matrix is ​​cyclically shifted by one row to form a matrix having a cyclic structure in the diagonal direction starting from the second row.

4. In paragraph 1, the l-th DD signal matrix among the L DD signal matrices is mathematical formula Here and diag(·) is a diagonal matrix in which the elements of (·) are arranged diagonally. Transmission method of an OTFS system obtained according to 5. In claim 1, the step of acquiring the encoded signal vector Each of the above L diffusion signal vectors is divided into the above L unit diffusion vectors, and The L unit diffusion vectors divided from each diffusion signal vector are sequentially mapped to L time intervals, A transmission method of an OTFS system for obtaining an encoded signal vector by selecting and extracting one unit diffusion vector from each time interval from L unit diffusion vectors mapped to L time intervals.

6. In paragraph 5, the above-mentioned encoded signal vector is A transmission method of an OTFS system obtained by extracting unit diffusion vectors that are cyclically arranged diagonally based on the unit diffusion vector mapped from each time interval among L unit diffusion vectors mapped to each of L time intervals.

7. In paragraph 5, the encoded signal vector (c) for the l-th signal interval l )Is mathematical formula (here, u l (i) (l, i ∈ {1, …, L}) is the l-th diffusion signal vector (u l The i-th unit diffusion vector split from ) Transmission method of an OTFS system obtained according to 8. In paragraph 1, the L diffusion signal vectors are A transmission method of an OTFS system obtained by spreading and encoding each of the L layer information symbol vectors according to the spreading coding technique used in the FDFR method of a MIMO system.

9. In paragraph 1, the L diffusion signal vectors (u k )Is The above layer information symbol vector (x k , k ∈ {1, … , L}) and the diffusion matrix (θ) set for each layer (k) k Multiply by ) It is obtained as, The above diffusion matrix (θ k )silver mathematical formula (Here F MN is an M×N Discrete Fourier Transform (DFT) matrix, and (·) H represents the conjugate transpose, diag(·) represents an MN×MN diagonal matrix, α is a factor set to distinguish information symbols within each layer (k), and β is a factor set to distinguish between layers. Transmission method of an OTFS system obtained according to 10. In paragraph 1, the information symbol vector is A transmission method of an OTFS system in which the L×M×N symbols obtained by digitally modulating the data of L OTFS frames to be transmitted during L time intervals are converted into a vector of size LMN×1.

11. In any one of paragraphs 1 to 10, the transmission method A transmission method of an OTFS system performed by the processor of a device including memory and a processor.

12. A device comprising one or more processors; and a memory for storing one or more programs executed by said one or more processors, wherein The above processor A step of dividing an information symbol vector composed of L×M×N symbols into L layered information symbol vectors, and spreading-coding each of the L layered information symbol vectors to obtain L spread signal vectors; A step of dividing each of the above L diffusion signal vectors into L unit diffusion vectors and mapping them to L time intervals, and obtaining an encoded signal vector composed of L unit diffusion vectors mapped to L time intervals; and A transmitting device of an OTFS system that performs the step of obtaining L DD signal matrices by distributing each of the obtained L encoded signal vectors into a delay-Doppler (hereinafter DD) domain consisting of M delay time grids and N Doppler grids in a diagonal cyclic structure.

13. In Clause 12, the above processor The above L encoded signal vectors, each having a size of MN×1, are divided into N unit encoded signal vectors, each having a size of M×1, and A transmitting device of an OTFS system that obtains L DD signal matrices by weighting a permutation matrix of order according to the position in the Doppler axis direction to a diagonal matrix in which the N distinguished unit encoded signal vectors are arranged diagonally.

14. In Clause 13, the above permutation matrix is A transmitting device of an OTFS system comprising a matrix in which each row of an M×M identity matrix is ​​cyclically shifted by one row to form a cyclic structure in the diagonal direction starting from the second row.

15. In Clause 12, the l-th DD signal matrix among the L DD signal matrices is mathematical formula Here and diag(·) is a diagonal matrix in which the elements of (·) are arranged diagonally. A transmitting device of the OTFS system acquired according to 16. In Clause 12, the above processor Each of the above L diffusion signal vectors is divided into the above L unit diffusion vectors, and The L unit diffusion vectors divided from each diffusion signal vector are sequentially mapped to L time intervals, A transmitting device of an OTFS system that obtains an encoded signal vector by selecting and extracting one unit diffusion vector from each time interval among L unit diffusion vectors mapped to L time intervals.

17. In paragraph 16, the above-mentioned encoded signal vector is A transmitting device of an OTFS system obtained by extracting unit diffusion vectors that are cyclically arranged diagonally based on the unit diffusion vector mapped from each time interval among L unit diffusion vectors mapped to each of L time intervals.

18. In paragraph 16, the encoded signal vector (c) for the l-th signal interval l )Is mathematical formula (here, u l (i) (l, i ∈ {1, …, L}) is the l-th diffusion signal vector (u l The i-th unit diffusion vector split from ) A transmitting device of the OTFS system acquired according to 19. In Clause 12, the above L diffusion signal vectors are A transmitting device of an OTFS system obtained by spreading and encoding each of the L layer information symbol vectors according to the spreading coding technique used in the FDFR method of a MIMO system.

20. In Clause 12, the above L diffusion signal vectors (u k )Is The above layer information symbol vector (x k , k ∈ {1, … , L}) and the diffusion matrix (θ) set for each layer (k) k Multiply by ) It is obtained as, The above diffusion matrix (θ k )silver mathematical formula (Here F MN is an M×N Discrete Fourier Transform (DFT) matrix, and (·) H represents the conjugate transpose, diag(·) represents an MN×MN diagonal matrix, α is a factor set to distinguish information symbols within each layer (k), and β is a factor set to distinguish between layers. A transmitting device of the OTFS system acquired according to

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