Apparatus including DMA and method for optimizing DMA elements thereof

Abstract

The present invention relates to a transmitting device including a dynamic metasurface antenna and a method for optimizing DMA elements therein, wherein a DMA weight matrix for activating DMA elements is defined in correspondence with at least one DMA spatial modulation control method, an optimization objective function for the defined DMA weight matrix is ​​defined according to the DMA spatial modulation control method, and an optimization coefficient for activating DMA elements is calculated using the defined optimization objective function.

Description

Technology Field

[0001] The present invention relates to a transmitting device including a dynamic metasurface antenna and a method for optimizing DMA elements therein. Background Technology

[0002] The content described in this section merely provides background information regarding the present embodiment and does not constitute prior art.

[0003] The demand for wireless communication services continues to increase due to the emergence of new use cases such as remote surgery, autonomous vehicles, and human-machine communication. Additionally, it is projected that the number of 5th generation (5G) wireless communication subscribers will reach approximately 4.8 billion by the end of 2028, accounting for more than half of all mobile subscribers.

[0004] To meet this increasing demand, various technologies and processing techniques are being proposed and researched to support next-generation wireless communication. Massive Multiple-Input Multiple-Output (mMIMO) antenna configurations are one such example; in mMIMO, spectral efficiency can be significantly improved due to array gain, spatial diversity, and spatial multiplexing gains that increase linearly with the number of antennas. To fully utilize the advantages of mMIMO, each antenna element must be equipped with its own baseband and RF (Radio Frequency) chain, which is generally referred to as a fully digital architecture. In a fully digital architecture, transceivers can adjust both the amplitude and phase of the signal, thereby providing a high degree of freedom in signal processing. However, considering that mMIMO consists of a very large number of antenna elements (e.g., up to 10²⁴ elements), equipping each element with its own RF chain presents the problem of causing high capital expenditures (CAPEX) and operating expenditures (OPEX).

[0005] To address the significant capital expenditures (CAPEX) and operating expenses (OPEX) associated with each antenna having its own RF (Radio Frequency) chain in mMIMO systems, various technologies such as analog architectures, hybrid architectures, and Index Modulation (IM) are being introduced.

[0006] In addition, new antenna architectures such as graphene-based and dynamic metasurface antennas (DMAs) that utilize the unique properties of graphene and metamaterials are being proposed to further reduce CAPEX and OPEX. The problem to be solved

[0007] The present invention is proposed to solve the aforementioned conventional problems, and aims to provide a transmitting device including a dynamic metasurface antenna (DMA) capable of calculating optimization coefficients for DMA element optimization in a transmitting device including a dynamic metasurface antenna, and a method for optimizing DMA elements in the same.

[0008] However, the objectives of the present invention are not limited to the above objectives, and other unmentioned objectives will be clearly understood from the description below. means of solving the problem

[0009] A method for optimizing DMA elements in a transmitting device including a Dynamic Metasurface Antennas (DMA) according to an embodiment of the present invention for achieving the purpose described above may comprise: a step of defining a DMA weight matrix for activating DMA elements corresponding to at least one DMA spatial modulation control method; a step of defining an optimization objective function for the defined DMA weight matrix according to the DMA spatial modulation control method; and a step of calculating optimization coefficients for activating DMA elements using the defined optimization objective function.

[0010] At this time, the DMA spatial modulation control method may include at least one of an element-wise DMA spatial modulation control method for activating any one DMA element, a microstrip-wise DMA spatial modulation control method for activating all DMA elements within any one microstrip, and a generalized spatial modulation control method for activating all DMA elements within at least two microstrips.

[0011] At this time, in the step of defining the optimization objective function, if the DMA spatial modulation control method is an element-unit or microstrip-unit DMA spatial modulation control method, an objective function to maximize the received signal-to-noise ratio (SNR) of the DMA element is defined, and if the DMA spatial modulation control method is a generalized spatial modulation control method, an objective function to maximize the overall spectral efficiency of the DMA element can be defined.

[0012] At this time, in the step of calculating optimization coefficients for the activation of the DMA elements, if the DMA spatial modulation control method is an element-unit or microstrip-unit DMA spatial modulation control method, the DMA weights are calculated according to a formula satisfying a closed-form solution, and the optimal DMA weight matrix reconstructed by reflecting the calculated DMA weights in the defined DMA weight matrix is ​​calculated as the optimization coefficients; and if the DMA spatial modulation control method is a generalized spatial modulation control method, the optimization coefficients can be calculated by alternately repeating the process until the convergence condition of the optimization objective function defined by corresponding the DMA weight matrix reconstructed by reflecting the DMA weights set as initial values ​​in the defined DMA weight matrix and the digital precoder coefficients calculated based on singular value decomposition is satisfied.

[0013] In a transmitting device including a dynamic metasurface antenna (DMA) according to an embodiment of the present invention for achieving the purpose described above, a DMA weight matrix for activating DMA elements is defined corresponding to at least one DMA spatial modulation control method, an optimization objective function for the defined DMA weight matrix is ​​defined according to the DMA spatial modulation control method, and optimization coefficients for activating DMA elements can be calculated using the defined optimization objective function. Effects of the invention

[0014] According to the transmitting device including a dynamic metasurface antenna of the present invention and the DMA element optimization method therein, the energy efficiency, data transmission efficiency, and adaptability of a DMA-based transmitting device can be maximized, and system complexity and operating costs can be minimized.

[0015] In particular, according to the present invention, a suitable spatial modulation method can be selected depending on the activated state of the DMA element of the transmitting device, and communication stability and signal strength can be improved by maximizing signal quality (SNR) through an element-unit or microstrip-unit DMA-SM method, and data transmission speed can be increased and bandwidth utilization efficiency can be maximized through a DMA-GSM method that activates multiple microstrips.

[0016] In addition, various effects other than those described above may be disclosed directly or implicitly in the detailed description according to the embodiments of the present invention to be described below. Brief explanation of the drawing

[0017] FIG. 1 is a block diagram illustrating a transmitting device according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating an optimization method according to an embodiment of the present invention. FIGS. 3 to 5 are illustrative diagrams for explaining a DMA space modulation control method according to an embodiment of the present invention. FIGS. 6 and FIGS. 7 are pseudocodes for explaining an algorithm according to an embodiment of the present invention. FIGS. 8 to 11 are graphs illustrating the effects according to an embodiment of the present invention. Specific details for implementing the invention

[0018] Preferred embodiments that can be easily practiced by those skilled in the art to which the present invention pertains are described in detail below with reference to the attached drawings. However, in describing the operating principles of the preferred embodiments of the present invention in detail, if it is determined that a specific description of related known functions or configurations may unnecessarily obscure the essence of the present invention, such detailed description is omitted. This is intended to convey the core of the present invention more clearly without obscuring it by omitting unnecessary descriptions. Furthermore, since the present invention is susceptible to various modifications and may have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description; however, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the present invention.

[0019] Furthermore, the terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. Additionally, terms such as “comprising” or “having” described in this specification are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0020] In addition, the present invention uses the following notation. First, lowercase italic x, bold lowercase x , And bold uppercase letters represent a scalar vector, a column vector, and a matrix, respectively, and in complex numbers is the argument of that complex number, and Each represents the real part and the imaginary part. class represent the real and complex number domains, respectively, and , and represents the transpose, conjugate transpose, and inverse operations, respectively. silver It refers to an identity matrix of size, is a matrix It refers to the element of the m-th row and n-th column. And is a vector It refers to the nth element, and the floor function and the Kronecker multiplication operation are, respectively and It is displayed as. Finally and represents the Frobenius norm and the determinant, respectively.

[0021] Hereinafter, a transmitting device including a dynamic metasurface antenna (DMA) according to an embodiment of the present invention and a method for optimizing DMA elements therein will be described.

[0022] FIG. 1 is a block diagram illustrating a transmitting device according to an embodiment of the present invention.

[0023] Referring to FIG. 1, a transmitting device (100) according to one embodiment of the present invention may be configured to include a memory (10) and a processor (20).

[0024] In one embodiment, the memory (10) may store information of any form generated or determined by the processor (20). The memory (10) of the present invention may include at least one type of storage medium among a flash memory type, a hard disk type, a multimedia card micro type, a card type memory (e.g., SD or XD memory, etc.), RAM (Random Access Memory), SRAM (Static Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), PROM (Programmable Read-Only Memory), magnetic memory, a magnetic disk, and an optical disk. Additionally, the memory (10) of the present invention may be implemented in the form of web storage. The description of the memory described above is merely an example and is not limited thereto.

[0025] The processor (20) performs overall processing according to an embodiment of the present invention and may be composed of one or more cores and may include a processor for data analysis and deep learning, such as a central processing unit (CPU), a general purpose graphics processing unit (GPGPU), and a tensor processing unit (TPU).

[0026] The processor (20) of the present invention can read a computer program stored in memory (10) and perform data processing according to one embodiment of the present invention. That is, the processor (20) of the present invention can define a DMA weight matrix according to the activated state of a DMA element constituting a dynamic metasurface antenna, define an optimization objective function according to a DMA spatial modulation control method corresponding to the defined DMA weight matrix, and perform processing for the entire process of calculating the optimization coefficient of the DMA element using the defined optimization objective function.

[0027] A transmitting device (100) including the processor (20) of the present invention may be, for example, a base station (BS) using a DMA-based antenna architecture. The base station is a terminal node of a network that communicates directly with a user's terminal and may be replaced by terms such as fixed station, Node B, eNode B (eNB), and Access Point (AP). However, depending on the implementation method, the operation of the present invention may be performed by an upper node of the base station.

[0028] Additionally, the transmitting device (100) of the present invention may be a user terminal (UE, User Equipment) to which a DMA-based antenna architecture is applied. That is, the transmitting device (100) of the present invention includes a DMA antenna, and any device that is a network node transmitting a signal can operate as the transmitting device (100) of the present invention.

[0029] Hereinafter, an optimization method in a transmitting device (100) according to an embodiment of the present invention will be described with reference to FIGS. 2 to 11. Here, FIG. 2 is a flowchart for explaining an optimization method according to an embodiment of the present invention, FIGS. 3 to 5 are illustrative diagrams for explaining a DMA spatial modulation control method according to an embodiment of the present invention, and FIGS. 6 and 7 are pseudocodes for explaining an algorithm according to an embodiment of the present invention. FIGS. 8 to 11 are graphs illustrating effects according to an embodiment of the present invention.

[0030] In addition, for the convenience of explanation, the transmitting device (100) is described as a base station (BS), but as previously mentioned, it is not limited thereto, and drawing symbols may be omitted, but any configuration that performs the same name or the same operation may be the same configuration.

[0031] A network system including a base station (BS) of the present invention considers a single-user downlink system using a DMA-based antenna architecture. DMA is one of the promising approaches for implementing a practical large-scale multiple-input multiple-output (mMIMO) system, which is a metamaterial radiator in which metamaterial elements are placed in a waveguide, commonly called a microstrip, and can provide various beam patterns and signal processing functions while maintaining low power consumption and production costs. Each microstrip is connected to a single RF chain, and an input signal from the RF chain can be radiated by each element connected to a specific microstrip.

[0032] In the present invention, the transmitting device There are microstrips, and each microstrip is It can be assumed that it has DMA elements. Therefore, the total number of DMA elements in the transmitting device is and the receiving device Let's assume that it has DMA elements.

[0033] In addition, the DMA of the present invention includes a device composed of metamaterials, and since such a device can manipulate the characteristics of electromagnetic waves, each DMA element can control the phase and amplitude of a radio wave signal. That is, the DMA element of the present invention may refer to a device capable of performing phase shifting and amplitude modulation through electronic control. Hereinafter, 'DMA element' may be referred to as 'element'.

[0034] In addition, as an input signal from the RF chain propagates through the microstrip, it undergoes attenuation due to material properties and phase change due to the position of the metamaterial element, and this propagation effect at the n-th element of the m-th microstrip can be expressed as follows:

[0035] <Mathematical Formula 1>

[0036]

[0037] Here, is the position of the n-th element of the m-th microstrip, and and represents the waveguide attenuation coefficient and the wavenumber of the m-th microstrip, respectively. Additionally, each DMA element is considered a frequency-dependent resonant circuit and has reconfigurable weights. Furthermore, if the system is considered frequency-flat, the frequency response can be represented using Lorentzian-constrained phase weights. For the n-th element of the m-th microstrip, the frequency response can be expressed as shown in the following equation.

[0038] <Mathematical Formula 2>

[0039]

[0040] Here, It represents a reconfigurable phase shift.

[0042] In such a transmitting device (100), the transmitting device (100) of the present invention defines a DMA weight matrix as shown in FIG. 2 (S100). Here, the DMA weight matrix is ​​defined in correspondence with at least one DMA spatial modulation control method, wherein the DMA spatial modulation control method may include an element-wise DMA spatial modulation control method for activating one DMA element, a microstrip-wise DMA spatial modulation control method for activating all DMA elements within one microstrip, and a generalized spatial modulation control method for activating all DMA elements within at least two microstrips.

[0043] And the transmitting device (100) of the present invention defines an optimization objective function for activating DMA elements corresponding to a defined DMA weight matrix (S110), and can calculate optimization coefficients using the optimization objective function (S130).

[0044] Each of these steps of the present invention can be clearly supported through the process described below.

[0046] A. DMA-based Spatial Modulation (SM)

[0047] In the case of spatial modulation (hereinafter referred to as 'SM'), the base station (BS) uses a single RF chain, which, as illustrated in FIGS. 3 and 4, through a switching mechanism It can be connected to one of the microstrips.

[0048] The DMA-based architecture of the present invention can apply two types of SMs.

[0049] First, as illustrated in FIG. 2, an element-wise DMA-SM control method can be implemented by activating one DMA element (510) of the microstrip based on the reconfigurability and switching mechanism of the DMA. Since only one DMA element (510) is activated, the DMA weight design is simplified, which can reduce computational complexity. Therefore, it may be suitable for applications requiring low complexity and / or time sensitivity.

[0050] In addition, as illustrated in FIG. 3, the microstrip-wise DMA-SM control method is implemented by activating all DMA elements within one microstrip at a time as indicated by 520, and By utilizing multiple elements for transmission, higher array gain can be provided, and this method can be advantageous in long-distance communication scenarios where signal strength is critical.

[0051] Below, the element-unit DMA-SM will be explained in more detail.

[0053] A.1 Element-unit DMA-SM

[0054] As shown in FIG. 3, in the case of an element-unit DMA-SM, only one DMA element (510) is activated at a time, and the rest The elements may remain in a disabled state. Specifically, of the unselected microstrip The element can be deactivated by connecting a single RF chain to a selected microstrip through a switching mechanism.

[0055] Meanwhile, of the selected microstrip The elements can be disabled by setting their weights to 0, which is in Equation 2 It can be implemented by setting it to. Consequently, the total number of bits that can be transmitted simultaneously It can be derived by the following mathematical formula.

[0056] <Mathematical Formula 3>

[0057]

[0058] Here, M is the APM modulation order, in <Equation 3> Bits are used to form APM symbols, and The bit can be used to select the activated element z. Here, z represents the l-th element of the k-th microstrip as shown in the following mathematical formula.

[0059] <Mathematical Formula 4>

[0060]

[0061] When transmission occurs, the receiving device receives a reception signal It can be expressed by the following mathematical formula.

[0062] <Mathematical Formula 5>

[0063]

[0064] Here, means transmitted power, and is a channel matrix, and is a diagonal matrix representing the propagation effect inside the waveguide, which can be expressed by the following mathematical formula.

[0065] <Mathematical Formula 6>

[0066]

[0067] Here, It is. And is a transmitted signal, with a single non-zero element at the k-th position having, here, is a modulated symbol with unit average power, and is additive white Gaussian noise (AWGN) at the receiving device, and can be defined by the following mathematical formula as the DMA reconstruction weight matrix.

[0068] <Mathematical Formula 7>

[0069]

[0070] By applying a Maximum Likelihood (ML) detector at the receiving device, the transmitted symbols and activated elements can be jointly reconstructed as shown in the following mathematical formula.

[0071] <Mathematical Formula 8>

[0072]

[0073] Here, M refers to a set containing M possible APM modulation symbols, and represents the column vector of the channel matrix G corresponding to the activated transmitting element.

[0074] In this method, the goal is to find the DMA reconstruction weight matrix Q to maximize the received SNR. The optimization objective function P0 to achieve this can be defined as shown in the following mathematical equation.

[0075] <Mathematical Formula 9>

[0076]

[0078] A.2 Microstrip Unit DMA-based SM

[0079] A significant disadvantage of element-unit DMA-SM is that it experiences low array gain because there is only one active element. As a result, this method is mainly suitable for wireless environments with short communication distances or small path loss, or high SNR regions. To solve this problem, the present invention proposes a microstrip-unit DMA-SM that can increase array gain while maintaining the advantages of SM.

[0080] As illustrated in FIG. 3, the base station (BS) uses a single RF chain and is connected to a single microstrip according to the information bit. This means that only all DMA elements within one microstrip are activated at a time, and the rest This means that the microstrips are disabled. Consequently, the number of bits that can be transmitted simultaneously It can be defined as shown in the following mathematical formula.

[0081] <Mathematical Formula 10>

[0082]

[0083] Here, The bit is used to determine the index k of the activated microstrip, and Bits can be used to form APM symbols.

[0084] Comparing the aforementioned <Equation 3> and <Equation 10>, the element-unit DMA-SM is compared to the microstrip-unit DMA-SM More bits can be transmitted. However, thanks to array gain, microstrip-unit SMs achieve higher spectral efficiency than element-unit SMs.

[0085] In a microstrip unit DAM-SM, the received signal can be expressed by the above-described <Equation 6>, and the difference lies in the DMA weight matrix Q. Specifically, the DMA weight matrix Q can be defined as shown in the following equation.

[0086] <Mathematical Formula 11>

[0087]

[0088] In addition, the transmitted APM symbol and the activated microstrip can be jointly restored using an ML detector at the receiver as shown in the following mathematical formula.

[0089] <Mathematical Formula 12>

[0090]

[0091] Here, represents a submatrix of the channel matrix G corresponding to the k-th microstrip, and represents a submatrix of H representing the waveguide propagation effect corresponding to the k-th microstrip, and represents a vector composed of non-zero elements of the k-th column of the DMA weight matrix Q.

[0092] Likewise, this technique aims to design the DMA reconstruction weight Q by optimizing it to maximize the received SNR, and thus the optimization objective function problem P1 can be defined as the following mathematical equation.

[0093] <Mathematical Formula 13>

[0094]

[0095] The constraint (st) at this time is <Equation 11>.

[0097] B. DMA-based GSM

[0098] One of the known limitations of SM is that spectral efficiency increases slowly logarithmically with the number of transmitting antennas. To address this, GSM was proposed, and instead of a single element A subset of antenna elements can be activated simultaneously. The activated antennas can transmit the same or different APM symbols, which can significantly improve spectral efficiency compared to SM. However, this results in higher detection complexity, and the simultaneous activation of multiple antennas requires more sophisticated signal processing to accurately detect and demodulate data.

[0099] If this is extended to a DMA-based architecture, the base station (BS) It is equipped with 2 microstrips, and each microstrip is It has elements, and therefore the total number of transmitted elements is is. Also, The microstrips are activated simultaneously Transmits two different APM symbols, and the rest The microstrips can be kept in a deactivated state.

[0100] Therefore, the base station (BS) Using multiple RF chains Precode the data stream. If you set it to, Compared to the case, system performance can be significantly improved while maintaining reasonable CAPEX and OPEX.

[0101] Consequently, the total number of bits that can be transmitted simultaneously It can be defined as shown in the following mathematical formula.

[0102] <Mathematical Formula 14>

[0103]

[0104] Here, is a binomial coefficient, and in <Equation 14> silver It is a bit used to generate APM symbols, and Is In the microstrips It refers to the bits used to select n microstrip combinations (MC). When the n-th microstrip combination is selected, represents the index of the microstrip, and and am.

[0105] The transmitting device has unit power When transmitting, the receiving device sends a reception signal It can be defined according to the following mathematical formula.

[0106] <Mathematical Formula 15>

[0107]

[0108] Here, represents the baseband digital precorder matrix applied to the n-th microstrip combination (MC), and is a matrix representing the switching operation corresponding to the n-th MC, and the column vector can be expressed by the following mathematical formula.

[0109] <Mathematical Formula 16>

[0110]

[0111] Here, is the identity matrix It means the j-th column of.

[0112] In addition, Q is a block diagonal matrix representing the DMA reconstruction weights, which can be defined as shown in the following mathematical formula.

[0113] <Mathematical Formula 17>

[0114]

[0115] The goal of the present invention in this technique is a digital precorder spectral efficiency by designing DMA weighting Q By maximizing [this], the spectrum efficiency of a GSM-based system in the case of an existing hybrid sub-connected MIMO architecture can be expressed as shown in the following mathematical formula.

[0116] <Mathematical Formula 18>

[0117]

[0118] Here,

[0119] And, A represents the phase converter-based analog precoding matrix.

[0120] One of the advantages of DMA is that analog signal processing can be naturally implemented using DMA elements without additional phase converters. Therefore, if A is replaced with HQ, the spectral efficiency of DMA-GSM can be expressed as shown in the following mathematical formula.

[0121] <Mathematical Formula 19>

[0122]

[0123] Based on <Equation 18> and <Equation 19>, for maximizing spectral efficiency The optimization objective function problem P2 of Q can be defined as shown in the following mathematical formula.

[0124] <Mathematical Formula 20>

[0125]

[0126] Here, is a set of N baseband digital precorders and represents the value calculated by substituting <Equation 19> into <Equation 18>.

[0128] The proposed method for DMA-SM of the present invention refers to a proposed solution for element-unit SM and a proposed solution for microstrip-unit SM.

[0129] A. Element-unit SM

[0130] To solve the optimization problem P0, the SNR expression can be simplified as shown in the following mathematical formula by assuming that only a single element is activated at a time.

[0131] <Mathematical Formula 21>

[0132]

[0133] Here, is a constant term and As the SNR expression after omitting, after obtaining the simplified SNR expression, the complex term to solve the Lorentzian constraint of <Equation 7> and exponent term It can be divided into. Using this, SNR can be additionally expressed as shown in the following mathematical formula.

[0134] <Mathematical Formula 22>

[0135]

[0136] In <Equation 22>, the first term is independent of the DMA weights and is therefore considered a constant; thus, problem P0 can be reconstructed as follows by considering only the second term.

[0137] <Mathematical Formula 23>

[0138]

[0139] To maximize the aforementioned problem function P0-A, so that the imaginary part of the objective function becomes 0 must be selected. Specifically, the optimal phase angle can be set by the following mathematical formula.

[0140] <Mathematical Formula 24>

[0141]

[0142] This may be the optimal phase angle to maximize the SNR of the DMA-based SM when activating a single element.

[0144] B. Microstrip Unit DMA-SM

[0145] To solve the microstrip unit SM problem function P1 according to an embodiment of the present invention, one can start by simplifying the SNR expression by assuming that only one microstrip is activated at a time, similar to problem function P0. In addition, the constant in the above-described <Equation 13> and Except for , an objective function as shown in the following mathematical formula can be derived.

[0146] <Mathematical Formula 25>

[0147]

[0148] Here, And, and is the element corresponding to the activated microstrip in the k-th column of Q It is a vector composed of. Also, similar to element-unit SM, to handle the Lorentzian constraint, It is divided into complex terms and exponential terms, and through this It can be expressed as shown in the following mathematical formula.

[0149] <Mathematical Formula 26>

[0150]

[0151] Here, (a) is It can be derived by using the fact that it is a Hermite matrix.

[0152] To maximize the SNR, the present invention focuses on the real term, and the problem function P1 can be reconstructed as shown in the following mathematical formula.

[0153] <Mathematical Formula 27>

[0154]

[0155] Here, the constraint is am.

[0156] Likewise, in order to maximize the real term of the objective function, in the present invention For , so that the imaginary part becomes 0 You must acquire it. Through this, It can be set as shown in the following mathematical formula.

[0157] <Mathematical Formula 28>

[0158]

[0159] Algorithm 1 illustrated in Fig. 6 is all of the activated microstrip as described above. It illustrates the algorithm for the elements.

[0161] Regarding the computational complexity of the DMA-SM technique according to an embodiment of the present invention, first, the weight of the activated DMA element of the element-unit DMA-SM of the present invention is a constant for the DMA phase. By setting it to this, it is obtained simply, so there is no computational load. In addition, in this method In the middle of the beat Active DMA elements can be selected via an SM mapping lookup table using bits. The lookup table is created only once, and the creation complexity may vary depending on the number of possible combinations. However, retrieving an element from the table is a constant-time operation unaffected by the total number of possible combinations, so the complexity is is. Therefore, the total computational complexity of the element unit DMA-SM of the present invention is am.

[0162] Meanwhile, in the case of the microstrip unit DMA-SM, similar to the element unit DMA-SM, the activated microstrip is It is selected via the SM mapping table using bits, and the table access complexity is The computational complexity of the microstrip unit DMA-SM of the present invention is mainly matrix It is governed by computation, and complexity is Therefore, the total computational complexity of the microstrip unit DMA-SM algorithm of the present invention is am.

[0164] The DMA-GSM optimization method of the present invention will be described.

[0165] The present invention is a proposed solution to the DMA-based GSM optimization problem. When observing the spectral efficiency in the above-described <Equation 20>, it may be difficult to optimize Q and D due to the structure. To solve this problem, the present invention intends to use a high-SNR approximation.

[0166] Using the high SNR approximation, the spectral efficiency can be expressed as shown in the following mathematical formula.

[0167] <Mathematical Formula 29>

[0168]

[0169] The high SNR approximation has asymptotic optimality, and the optimization of Q and D based on the above-described <Equation 29> can be derived as equivalent to the actual spectral efficiency optimization of <Equation 20> at high SNR.

[0170] Using <Mathematical Formula 29>, Problem P2 can be restructured into Problem P2-A as shown in the following mathematical formula.

[0171] <Mathematical Formula 30>

[0172]

[0173] Here, am.

[0174] This is an equation obtained by removing the constant term of the aforementioned <Equation 29> and considering the natural logarithm instead of the binary logarithm.

[0175] Even with the use of high SNR approximation, the optimization problem P2-A remains difficult to solve because Q and D are interrelated. To address this, the present invention proposes an alternating optimization strategy in which Q is optimized when D is fixed, and D is optimized when Q is fixed.

[0177] A. Optimization of DMA weights

[0178] With the transmitting precoder D fixed, to optimize the DMA weight Q, Q can be represented as a diagonal matrix by modifying the structures of H and Q. A diagonal matrix consisting of the non-zero elements of Q. It can be defined as shown in the following mathematical formula.

[0179] <Mathematical Formula 31>

[0180]

[0181] And the block diagonal matrix generated in H It can be defined as shown in the following mathematical formula.

[0182] <Mathematical Formula 32>

[0183]

[0184] According to the above-described <Mathematical Formula 31> and <Mathematical Formula 32> It can be expressed as shown in the following mathematical formula.

[0185] <Mathematical Formula 33>

[0186]

[0187] Here, (a) is the determinant property of a diagonal matrix Apply, that is And, and am.

[0188] Also, (b) is Applying Singular Value Decomposition (SVD) to, i.e., Following, at this time, and is the identity matrix constituting the left and right singular vectors, respectively, and is a diagonal matrix, and the non-zero diagonal elements are It is a singular value of. Also, (c) is the determinant property It is the application of

[0189] Based on the above-described <Equation 33>, the optimization problem for the DMA reconstruction weight Q can be defined as the problem function P3 as shown in the following equation.

[0190] <Mathematical Formula 34>

[0191]

[0192] The constraint (st) at this time is defined in <Equation 31>, and am.

[0193] The solution to the unconstrained optimization problem P3 is It can be obtained by setting it to. Here, Is The first of It is a matrix composed of columns. Using this, in a constrained problem, the present invention aims to minimize the distance between the unconstrained optimal solution and the constrained solution for a fixed digital precoder D by designing DMA weights Q.

[0194] <Mathematical Formula 35>

[0195]

[0196] The constraint (st) at this time is defined in <Equation 31>.

[0197] If the projection operation of the aforementioned <Equation 35> is extended, <Equation 35> is It can be divided into several independent subproblems, and each term is associated with a single DMA element.

[0198] <Mathematical Formula 36>

[0199]

[0200] Here, (a) is a property of diagonal matrices According to, considering a single DMA element k, the following mathematical formula can be obtained.

[0201] <Mathematical Formula 37>

[0202]

[0203] Constraints And, and am.

[0204] As explained earlier, we propose separating the Lorenz constraint into a constant complex term and an exponential term, and the constraint If we substitute this into <Equation 37>, it can be defined as the following equation.

[0205] <Mathematical Formula 38>

[0206]

[0207] Here, am.

[0208] If the constant term is omitted in the aforementioned <Mathematical Equation 38>, the optimal It can be obtained through the following optimization problem.

[0209] <Mathematical Formula 39>

[0210]

[0211] The optimal phase change that minimizes the above-described <Equation 39> can be expressed as the following equation.

[0212] <Mathematical Formula 40>

[0213]

[0215] B. Optimization of digital precoders

[0216] Using the acquired DMA weight matrix Q, the digital precorder D is optimized. From the problem function P2-A, the objective function for optimizing the digital precorder can be defined as follows:

[0217] <Mathematical Formula 41>

[0218]

[0219] Here, am.

[0220] This can be expressed step-by-step as follows. First, (a) is Apply the SVD of, and here, and are left and right singular vector matrices each composed of an identity matrix, and is a singular value diagonal matrix. And (b) is the determinant property It is the application of

[0221] Based on the aforementioned <Mathematical Formula 41>, the digital precorder The optimization problem P4 for can be defined by the following mathematical formula.

[0222] <Mathematical Formula 42>

[0223]

[0224] Constraints, am.

[0225] In optimization problem P4, the optimal baseband digital precorder It can be defined by the following mathematical formula.

[0226] <Mathematical Formula 43>

[0227]

[0228] Algorithm 2 for the optimized DMA weight matrix and digital precorder design for DMA-based GSM is illustrated in Fig. 7.

[0230] The method according to the embodiment of the present invention has been described above.

[0231] As shown in FIG. 8, it can be seen that the received SNR is maximized at all transmission power levels, and as shown in FIG. 9, the lowest bit error rate (BER) can be achieved for element-unit SMs. As shown in FIG. 10, it can be confirmed that the technique of the present invention shows superior performance compared to other techniques and achieves the highest received SNR when considering microstrip-unit SMs, and as shown in FIG. 11, it can be confirmed that the spectral efficiency is also the highest.

[0232] The optimization method according to the embodiment of the present invention has been described above.

[0233] The optimization method of the present invention as described above may be provided in the form of a computer-readable medium suitable for storing computer program instructions and data.

[0234] Such computer-readable recording media may include program instructions, data files, data structures, etc., either individually or in combination, and include all types of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs (Compact Disk Read Only Memory) and DVDs (Digital Video Disks); magneto-optical media such as floptical disks; and hardware devices specifically configured to store and execute program instructions, such as ROM (Read Only Memory), RAM (Random Access Memory), and flash memory.

[0235] In addition, computer-readable recording media are distributed across networked computer systems, allowing computer-readable code to be stored and executed in a distributed manner. Furthermore, functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers skilled in the art to which the present invention pertains.

[0236] Although preferred embodiments illustrating the technical concept of the present invention have been described and illustrated above, the present invention is not limited to the configuration and operation as illustrated and described, and those skilled in the art will understand that numerous changes and modifications can be made to the present invention without departing from the scope of the technical concept. Accordingly, all such appropriate changes and modifications and equivalents should be considered to be within the scope of the present invention. Explanation of the symbols

[0237] 10: Memory 20: Processor 100: Transmitter

Claims

Claim 1 A method for optimizing DMA elements in a transmitting device including Dynamic Metasurface Antennas (DMA), wherein the transmitting device comprises: a step of defining a DMA weight matrix for activating DMA elements corresponding to at least one DMA spatial modulation control method; a step of defining an optimization objective function for the defined DMA weight matrix according to the DMA spatial modulation control method; and a step of calculating optimization coefficients for activating DMA elements using the defined optimization objective function; wherein the DMA spatial modulation control method is at least one of an element-wise DMA spatial modulation control method for activating one DMA element, a microstrip-wise DMA spatial modulation control method for activating all DMA elements within one microstrip, and at least two generalized spatial modulation control methods for activating all DMA elements within two or more microstrips; and in the step of defining the optimization objective function, if the DMA spatial modulation control method is an element-wise or microstrip-wise DMA spatial modulation control method, the received signal-to-noise ratio of the DMA element An optimization method characterized by defining an objective function to maximize the Ratio (SNR), and if the DMA spatial modulation control method is a generalized spatial modulation control method, defining an objective function to maximize the total spectral efficiency of the DMA element. Claim 2 delete Claim 3 delete Claim 4 An optimization method according to claim 1, wherein in the step of calculating optimization coefficients for activating the DMA elements, if the DMA spatial modulation control method is an element-unit or microstrip-unit DMA spatial modulation control method, the DMA weights are calculated according to a formula satisfying a closed-form solution, and the optimal DMA weight matrix reconstructed by reflecting the calculated DMA weights in the defined DMA weight matrix is ​​calculated as the optimization coefficients; and if the DMA spatial modulation control method is a generalized spatial modulation control method, the optimization coefficients are calculated by alternately repeating the process until the convergence condition of the optimization objective function defined by correspondingly reflecting the DMA weights set as initial values ​​in the defined DMA weight matrix and the digital precoder coefficients calculated based on singular value decomposition is satisfied. Claim 5 A transmitting device comprising Dynamic Metasurface Antennas (DMA), wherein a DMA weight matrix for activating DMA elements is defined corresponding to at least one DMA spatial modulation control method, an optimization objective function for the defined DMA weight matrix is ​​defined according to the DMA spatial modulation control method, and optimization coefficients for activating DMA elements are calculated using the defined optimization objective function, wherein the DMA spatial modulation control method is at least one of an element-wise DMA spatial modulation control method for activating any one DMA element, a microstrip-wise DMA spatial modulation control method for activating all DMA elements within any one microstrip, and a generalized spatial modulation control method for activating all DMA elements within at least two microstrips, and wherein defining the optimization objective function is, if the DMA spatial modulation control method is an element-wise or microstrip-wise DMA spatial modulation control method, an objective function for maximizing the received Signal-to-Noise Ratio (SNR) of the DMA elements is defined, and A transmitting device characterized by defining an objective function to maximize the total spectral efficiency of a DMA element, wherein the DMA spatial modulation control method is a generalized spatial modulation control method.

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