Non-line-of-sight physical layer security transmission method and device and storage medium

Abstract

The application discloses a non-line-of-sight physical layer security transmission method and device and a storage medium, relates to the technical field of wireless communication, and solves the problems of poor communication effect of a direct transmission link between a transmitter and an expected user and even non-existent security communication when the direct transmission link exists. The method comprises the following steps: establishing an intelligent metasurface assisted frequency control array system, and respectively calculating the steering vectors of the transmitter to the expected user, the intelligent metasurface to the expected user and the transmitter to the intelligent metasurface; acquiring and analyzing the signals received by the expected user and an eavesdropper, determining the analysis result, and designing a transmitting beamforming vector and an intelligent metasurface reflection coefficient matrix; calculating an artificial noise projection matrix; and transmitting symbol information according to the calculation result. The method can achieve the effects of secure communication of the transmitter and the expected user through the direct transmission link, more concentrated point-type beam energy and lower sidelobe energy without increasing the system bandwidth.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a non-line-of-sight physical layer secure transmission method, apparatus and storage medium. Background Technology

[0002] With the rapid development of information technology, wireless communication systems operate in complex environments. Besides being susceptible to interference from the natural environment and noise, they also face communication interruptions when direct transmission links are blocked. According to electromagnetics and antenna theory, microwave signals have poor scattering and diffraction capabilities, and experience significant attenuation and free path loss during propagation, resulting in insufficient reliability for long-distance communication.

[0003] Therefore, there is a high risk of poor communication between the transmitter and the intended user via a direct transmission link, or even a complete lack of direct transmission link communication due to obstruction. Summary of the Invention

[0004] This application provides a method, apparatus, and storage medium for non-line-of-sight physical layer secure transmission, which solves the problem of poor direct transmission link communication between the transmitter and the desired user in the prior art, or even the absence of a direct transmission link due to obstruction. It achieves the effects of secure direct transmission link communication between the transmitter and the desired user, more concentrated point beam energy, and lower sidelobe energy without increasing system bandwidth.

[0005] In a first aspect, embodiments of the present invention provide a non-line-of-sight physical layer secure transmission method, the method comprising:

[0006] A frequency control array system assisted by a smart metasurface is established, and the guiding vector of the transmitter to the desired user, the guiding vector of the smart metasurface to the desired user, and the guiding vector of the transmitter to the smart metasurface are calculated according to the positions of the smart metasurface and the desired user relative to the transmitter, respectively.

[0007] Acquire and analyze the signals received by the intended user and the eavesdropper, and determine the analysis results;

[0008] Based on the analysis results, the emitted beamforming vector and the intelligent metasurface reflection coefficient matrix were designed and calculated.

[0009] Calculate the projection matrix of the artificial noise;

[0010] The symbol information is transmitted based on the transmitted beamforming vector, the intelligent metasurface reflection coefficient matrix, and the artificial noise projection matrix.

[0011] In conjunction with the first aspect, in one possible implementation, the smart metasurface-assisted frequency control array system includes: a frequency control array antenna and a smart metasurface;

[0012] The frequency-controlled array antenna includes multiple uniformly arranged transmitting antennas;

[0013] The intelligent metasurface includes multiple reflective units.

[0014] In conjunction with the first aspect, in one possible implementation, the signal that the user is expected to receive is:

[0015] The signal that the user is expected to receive is:

[0016]

[0017] in, This represents the guidance vector of the transmitter towards the desired user; This represents the guidance vector of the intelligent metasurface to the desired user; Let be an M-dimensional diagonal matrix, representing the reflection coefficient matrix of the intelligent metasurface, where θ m Let α represent the phase shift of the m-th reflecting element, and α∈(0,1] represent the amplitude reflection coefficient. This represents the guiding vector of the transmitter to the smart metasurface; This represents additive white Gaussian noise in the desired channel.

[0018] The signal received by the eavesdropper is:

[0019]

[0020] in, This represents the guidance vector of the transmitter towards the eavesdropper; This represents the guidance vector of the intelligent metasurface to the eavesdropper; This represents additive white Gaussian noise in the eavesdropping channel.

[0021] In conjunction with the first aspect, in one possible implementation, the constraint for calculating the artificial noise projection matrix is ​​that the artificial noise interferes with the eavesdropper without affecting the signal received by the desired user.

[0022] In conjunction with the first aspect, in one possible implementation, the design and calculation of the emitted beamforming vector and the smart metasurface reflection coefficient matrix based on the analysis results includes the following constraints:

[0023] The emission shaping beam vector and the intelligent metasurface reflection coefficient matrix are designed using the method of maximizing artificial noise interference frequency;

[0024] The desired user power satisfies the minimum signal reception power so that the transmission power of the artificial noise is maximized.

[0025] In conjunction with the first aspect, in one possible implementation, the calculation of the artificial noise projection matrix includes: the calculation formula is: in, Represents the projection matrix of artificial noise. This represents the guidance vector of the transmitter towards the desired user. This represents the array steering vector of the smart metasurface for the desired user. This represents the guiding vector of the transmitter to the smart metasurface.

[0026] In a second aspect, embodiments of the present invention provide a non-line-of-sight physical layer secure transmission device, the device comprising:

[0027] The steering vector establishment module is used to establish a frequency control array system assisted by a smart metasurface, and calculate the steering vector of the transmitter to the desired user, the steering vector of the smart metasurface to the desired user, and the steering vector of the transmitter to the smart metasurface, respectively, based on the position of the smart metasurface and the desired user relative to the transmitter in the system.

[0028] The analysis module is used to acquire and analyze the signals received by the intended user and the eavesdropper, and determine the analysis results;

[0029] The vector calculation module is used to design and calculate the emitted beamforming vector and the intelligent metasurface reflection coefficient matrix based on the analysis results.

[0030] The projection matrix calculation module is used to calculate the projection matrix of artificial noise;

[0031] The signal transmission module is used to transmit symbol information based on the transmitted beamforming vector, the intelligent metasurface reflection coefficient matrix, and the artificial noise projection matrix.

[0032] In conjunction with the second aspect, in one possible implementation, the guide vector establishment module includes multiple frequency-controlled array antennas and a smart metasurface;

[0033] The multiple frequency-controlled array antennas include multiple uniformly arranged transmitting antennas;

[0034] The intelligent metasurface includes multiple reflective units.

[0035] In conjunction with the second aspect, in one possible implementation, the analysis module is used to calculate the signal that the user is expected to receive as:

[0036]

[0037] in, This represents the guidance vector of the transmitter towards the desired user; This represents the guidance vector of the intelligent metasurface to the desired user; Let be an M-dimensional diagonal matrix, representing the reflection coefficient matrix of the intelligent metasurface, where θ m Let α represent the phase shift of the m-th reflecting element, and α∈(0,1] represent the amplitude reflection coefficient. This represents the guiding vector of the transmitter to the smart metasurface; This represents additive white Gaussian noise in the desired channel.

[0038] The signal received by the eavesdropper is:

[0039]

[0040] in, This represents the guidance vector of the transmitter towards the eavesdropper; This represents the guidance vector of the intelligent metasurface to the eavesdropper; This represents additive white Gaussian noise in the eavesdropping channel.

[0041] In conjunction with the second aspect, in one possible implementation, the constraint condition for the projection matrix calculation module to calculate the artificial noise projection matrix is ​​that the artificial noise interferes with the eavesdropper but does not affect the signal received by the desired user.

[0042] In conjunction with the second aspect, in one possible implementation, the signal transmitting module is used to design and calculate the transmitted beamforming vector and the smart metasurface reflection coefficient matrix based on the analysis results, including the following constraints:

[0043] The emission shaping beam vector and the intelligent metasurface reflection coefficient matrix are designed using the method of maximizing artificial noise interference frequency;

[0044] The desired user power satisfies the minimum signal reception power so that the transmission power of the artificial noise is maximized.

[0045] In conjunction with the second aspect, in one possible implementation, the projection matrix calculation module is used to calculate the artificial noise projection matrix, including: the calculation formula is: in, Represents the projection matrix of artificial noise. This represents the guidance vector of the transmitter towards the desired user. This represents the array steering vector of the smart metasurface for the desired user. This represents the guiding vector of the transmitter to the smart metasurface.

[0046] Thirdly, embodiments of the present invention provide a transmitter for non-line-of-sight physical layer secure transmission, including a memory and a processor;

[0047] The memory is used to store computer-executable instructions;

[0048] The processor is configured to execute the computer-executable instructions to implement the method described in the first aspect or any one of the first aspects.

[0049] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing executable instructions, wherein a computer executing the executable instructions is capable of implementing the method described in the first aspect or any one of the first aspects.

[0050] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0051] This invention employs a non-line-of-sight physical layer secure transmission method, apparatus, and storage medium. The method includes: establishing a smart metasurface-assisted frequency control array system; calculating the transmitter's steering vector to the desired user, the smart metasurface's steering vector to the desired user, and the transmitter's steering vector to the smart metasurface, respectively, based on the positions of the smart metasurface and the desired user relative to the transmitter; acquiring and analyzing the signals received by the desired user and the eavesdropper, and determining the analysis results; designing and calculating the transmission beamforming vector and the smart metasurface reflection coefficient matrix based on the analysis results; calculating the artificial noise projection matrix; and transmitting symbol information based on the transmission beamforming vector, the smart metasurface reflection coefficient matrix, and the artificial noise projection matrix. The method provided in this application includes a smart metasurface, a desired user, and a transmitter, which improves system security. The smart metasurface can reconstruct and improve the wireless channel. By analyzing the signals received by the desired user and the eavesdropper, the frequency of the added artificial noise is calculated so that the transmission power of the artificial noise is maximized while the desired user meets the minimum received power. This effectively solves the problem of poor direct transmission link communication between the transmitter and the desired user in the prior art, or even the lack of a direct transmission link due to obstruction. It achieves secure direct transmission link communication between the transmitter and the desired user without increasing the system bandwidth. The point beam energy is more concentrated and the sidelobe energy is lower. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments of the present invention or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1This is a flowchart illustrating the steps of a non-line-of-sight physical layer secure transmission method provided in an embodiment of this application.

[0054] Figure 2 This is a schematic diagram of a smart metasurface-assisted frequency control array system provided in an embodiment of this application;

[0055] Figure 3 This is a schematic diagram of simulation parameters for the intelligent metasurface-assisted frequency control array system provided in the embodiments of this application.

[0056] Figure 4A The desired user location provided for the embodiments of this application is (20m, 50m, 0), and the desired user received modulation symbol power versus minimum SINR curve is shown.

[0057] Figure 4B The desired user location provided for this application embodiment is (480m, 50m, 0), and the desired user received modulation symbol power versus minimum SINR curve is shown.

[0058] Figure 4C The desired user location provided for this application embodiment is (300m, 50m, 0), and the desired user received modulation symbol power versus minimum SINR curve is shown.

[0059] Figure 5 The relationship between the number of transmit antennas and security capacity when providing different physical layer secure transmission methods in the embodiments of this application;

[0060] Figure 6 A schematic diagram of a non-line-of-sight physical layer secure transmission device provided in an embodiment of this application;

[0061] Figure 7 A schematic diagram of a transmitter for non-line-of-sight physical layer secure transmission provided in an embodiment of this application. Detailed Implementation

[0062] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0063] With the rapid development of information technology, wireless communication systems, when in complex environments, are not only susceptible to interference from natural environments and noise, but also face issues of communication reliability and security when direct transmission links are blocked. According to electromagnetics and antenna theory, microwave signals have poor scattering and diffraction capabilities, and experience significant attenuation and free path loss during propagation, resulting in insufficient reliability for long-distance communication. Therefore, scenarios often arise where direct transmission links between the transmitter and the intended user are poorly implemented, or even completely absent due to obstruction. Conventional physical layer secure transmission methods cannot guarantee secure information transmission. To address these problems, this invention provides a non-line-of-sight physical layer secure transmission method, such as... Figure 1 As shown, the method includes the following steps S101 to S105.

[0064] S101, establish a frequency control array system assisted by a smart metasurface, and calculate the guiding vector of the transmitter to the desired user, the guiding vector of the smart metasurface to the desired user, and the guiding vector of the transmitter to the smart metasurface, respectively, based on the positions of the smart metasurface and the desired user relative to the transmitter.

[0065] S102, acquire and analyze the signals received by the expected user and the eavesdropper, and determine the analysis results.

[0066] S103, based on the analysis results, designs and calculates the emitted beamforming vector and the intelligent metasurface reflection coefficient matrix.

[0067] S104, Calculate the artificial noise projection matrix.

[0068] S105 transmits symbol information based on the transmitted beamforming vector, the intelligent metasurface reflection coefficient matrix, and the artificial noise projection matrix.

[0069] This invention presents an information transmission method based on a frequency-controlled array transmitter structure, aiming to solve the problem of poor direct link communication between the transmitter and the intended user, or even the lack of a direct link due to obstruction, ensuring secure communication. Simultaneously, the array antenna employs random logarithmic frequency shifting, resulting in a more concentrated point beam with lower sidelobe energy without increasing system bandwidth. The beamforming matrix is ​​designed with minimum transmit information power to reduce information leakage, and the remaining transmit power is allocated to artificial noise, ensuring a reasonable distribution of transmit information power and artificial noise power for more efficient transmission.

[0070] In step S101, the smart metasurface-assisted frequency control array system includes: multiple frequency control array antennas and a smart metasurface; the multiple frequency control array antennas include multiple uniformly arranged transmitting antennas; the smart metasurface includes multiple reflecting elements.

[0071] Non-line-of-sight complex communication environments, such as Figure 2As shown, in a specific embodiment, the frequency-controlled array system consists of a uniform linear array of N antennas with an antenna spacing of d. The smart metasurface consists of M low-cost reflecting elements, with one antenna intended for a single user and multiple passive eavesdroppers in unknown locations. The smart metasurface dynamically adjusts the phase shift of the incident signal based on a controller to aid in reliable information transmission. The power of signals reflected twice or more by the smart metasurface is negligible. The first antenna of the transmitter is designated as the reference element. Considering the far-field signal transmission model of the target, both parallel wave and line-of-sight transmission are valid.

[0072] The transmitter uses a random logarithmic frequency-controlled array antenna, meaning the frequency increment is Δf. LR =P T Δf, where P = [c1, c2, ..., c i ,…,c N ], where c i Let represent the unit column vector whose i-th element is 1, where i∈{1,2,…,N}, and is randomly generated without repetition; Δf represents the frequency increment of the standard logarithmic frequency control matrix.

[0073] Artificial noise scrambling is employed to increase interference with eavesdroppers and improve system security. The transmitter performs phase modulation on the input bitstream, obtaining modulation symbols x∈Ω, where Ω is the set of modulation symbols that meets the normalization condition, i.e. The modulation symbols are weighted and artificial noise is introduced to obtain the final radiated signal vector. Among them, P AN Indicates the energy emitted by artificial noise; This represents the beamforming vector, which is further processed on the modulation symbol x to match all transmit antennas; in Represents the projection matrix of artificial noise. This represents the artificial noise vector.

[0074] In step S101, based on the position information of the smart metasurface and the desired user relative to the transmitter, the guiding vector of the transmitter to the desired user, the array guiding vector of the smart metasurface to the desired user, and the guiding matrix of the transmitter to the smart metasurface are calculated respectively.

[0075] The steering vector at the far-field position (r, θ) is:

[0076] h(f,r,θ,t)=ρ[h1(f1,r,θ,t),…,h n (f n ,r,θ,t),…,h N (f N ,r,θ,t)] T ,

[0077] in, ρ is the free-space path velocity loss coefficient of the wireless signal, c is the propagation of the electromagnetic wave in a vacuum, and f is the propagation velocity of the electromagnetic wave in a vacuum. n Let n be the transmission frequency of the nth antenna.

[0078] The use of smart metasurfaces can alter the wireless propagation environment, making it more favorable for signal transmission. Smart metasurfaces contain numerous passive reflective elements, each of which can be individually adjusted for amplitude and phase. Compared to traditional repeaters, smart metasurfaces offer lower hardware costs and lower power consumption.

[0079] In step S102, the signal that the user is expected to receive is:

[0080]

[0081] in, This represents the transmitter's steering vector toward the desired user; This represents the guidance vector of the intelligent metasurface to the desired user; Let be an M-dimensional diagonal matrix, representing the reflection coefficient matrix of the intelligent metasurface, where θ m Let α represent the phase shift of the m-th reflecting element, and α∈(0,1] represent the amplitude reflection coefficient. This represents the guiding vector of the transmitter to the smart metasurface; This represents the additive white Gaussian noise of the desired channel.

[0082] The signal that the user is expected to receive is further obtained as follows:

[0083]

[0084] The eavesdropper will intercept information on both the transmitter-smart metasurface transmission path and the smart metasurface-desired user transmission path. The signal received by the eavesdropper is:

[0085]

[0086] in, This represents the transmitter's guidance vector towards the eavesdropper; This represents the guidance vector of the intelligent metasurface to the eavesdropper; This represents additive white Gaussian noise in the eavesdropping channel. Further, we obtain:

[0087] In step S103, the emitted beamforming vector and the smart metasurface reflection coefficient matrix are designed and calculated based on the analysis results, including the following constraints:

[0088] The method of maximizing the artificial noise interference frequency is used to design the emission shaping beam vector and the intelligent metasurface reflection coefficient matrix; it is expected that the user power meets the minimum signal reception power so as to maximize the emission power of artificial noise.

[0089] Hypothesis vector The optimization problem is described as follows:

[0090]

[0091] in, γ represents the collection of intelligent metasurface reflective elements; γ represents the minimum signal-to-interference-plus-noise ratio requirement for users to reliably receive signals.

[0092] The total transmission power of the system is P. s =P AN +P L , where P L Let x represent the transmit power of the modulation symbol x, and The artificial noise transmission power is maximized by minimizing the modulation symbol transmission power. The optimization problem is equivalently transformed into...

[0093] For any given phase shift vector of a smart metasurface reflective element The optimal beamforming vector in the optimization problem is: To obtain the optimal modulation symbol transmit power:

[0094] The minimum modulation symbol transmit power is equivalent to the combined channel power gain of the maximum expected user, i.e., the optimization problem is transformed into: To make the objective function easier to handle, let

[0095] The objective function then becomes:

[0096] Further results were obtained:

[0097] The optimization problem remains non-convex, and the optimal solution cannot be obtained through traditional convex optimization. By introducing an auxiliary variable μ, the optimization problem is further transformed into: in,

[0098] Solving using the positive semidefinite relaxation method, matrix variables are introduced. Represented as:

[0099]

[0100] Matrix variable A ≥ 0, and rank(A) = 1. Also:

[0101]

[0102] Further results were obtained:

[0103]

[0104] stA m,m =1,m=1,2,…,M,M+1,

[0105] A≥0

[0106] This optimization problem is a convex optimization problem, and the optimal solution can be obtained using conventional convex optimization tools.

[0107] In step S104, the constraint condition for calculating the artificial noise projection matrix is ​​that the artificial noise interferes with the eavesdropper without affecting the signal received by the desired user.

[0108] In step S104, the artificial noise projection matrix is ​​calculated, including the following formula: based on the criterion that artificial noise interferes with the eavesdropper without affecting the signal received by the expected user, the expression for the artificial noise content in the signal received by the expected user is zero.

[0109] Therefore, the artificial noise projection matrix is ​​calculated by the following formula:

[0110]

[0111] Assumption The formula then simplifies to:

[0112]

[0113] in, Represents the projection matrix of artificial noise. This represents the transmitter's steering vector toward the desired user. This represents the array steering vector of the smart metasurface for the desired user. This represents the guiding vector of the transmitter to the smart metasurface.

[0114] Based on the transmitted beamforming vector, intelligent metasurface reflection coefficient matrix, and artificial noise projection matrix obtained from the above steps, the transmitted information is sent out through the antenna module, thus completing the work of the transmitting end.

[0115] In one specific embodiment of this application, such as Figure 3 As shown, the transmitter consists of a uniform linear array located along the x-axis, with its reference antenna positioned at (0,0,0). The smart metasurface consists of a uniform planar array located in the xy-plane, with its reference reflector positioned at (x...). R ,0,zR The user is expected to be located in the xy plane, with their position being (x...). L ,y L ,0). Transmitter - Desired transmission distance between users Smart metasurfaces - Desired transmission distance between users To verify the security of the proposed scheme, it is assumed that there are two eavesdroppers in the system. Eavesdropper 1 is located in the xz plane, at the same angle as the smart metasurface. Eavesdropper 2 is located in the xy plane.

[0116] The main parameters in the numerical simulation are shown in Table 1.

[0117] Table 1 Main parameters of numerical simulation

[0118]

[0119] Figure 4A , 4B When 4C represents different desired user locations, the total received modulation symbol power of the desired user is... and transmitter direct transmission modulation symbol power The relationship between the expected minimum received signal and the interference plus noise ratio (SINR). Figure 4A In the simulation, the desired user's location is (20m, 50m, 0), and the direct transmission distance from the transmitter to the desired user is approximately d1 ≈ 54m. At this point, the desired user is closer to the transmitter and farther from the smart metasurface. It is easy to see from the figure that the total received modulation symbol power of the desired user is almost identical to the transmitter's direct transmission modulation symbol power. This indicates that when the desired user is close to the transmitter, the received power of the smart metasurface reflected signal is very small and can be ignored. The desired user mainly relies on the transmitter's direct transmission link to receive modulation symbols. Figure 4B In the simulation, the desired user location is (480m, 50m, 0) (the desired user is close to the smart metasurface). The figure shows that the total received modulation symbol power of the desired user is much greater than the transmitter's direct-transmit signal power. This indicates that, under the combined effect of the transmitter's direct-transmit channel and the smart metasurface's reflection channel, the desired user can reliably receive the transmitted signal. Figure 4C In the simulation, the desired user location is (300m, 50m, 0), and it is assumed that there is an obstruction between the transmitter and the desired user. In this case, the transmitter cannot directly transmit the modulation symbols to the desired user. For example... Figure 4C As shown, it is expected that users can still meet the minimum received signal-to-interference-plus-noise ratio requirements by relying on the intelligent metasurface reflection link to receive modulation symbols. Figure 4A , 4B4C verifies the reliability of the provided method, ensuring that the intended user can reliably receive the transmitted signal even when there is an obstruction between the transmitter and the intended user.

[0120] Figure 5 The relationship between the number of transmitting antennas and the security capacity for different physical layer secure transmission methods is presented. The figure clearly shows that traditional frequency-controlled array secure transmission methods, lacking intelligent metasurface devices, are almost unable to reliably receive information from the intended user in scenarios where there are obstructions between the transmitter and the user. This can lead to untimely information transmission and significant losses in emergency situations such as rescue operations. Furthermore, phased array-based secure transmission methods cannot guarantee secure information transmission in the distance dimension. The figure shows that eavesdropper 1, with the same angle as the intelligent metasurface but at a different distance, can intercept confidential information transmitted on the transmitter-intelligent metasurface link, resulting in a near-zero system security capacity. The proposed method employs frequency-controlled array antenna technology, artificial noise scrambling technology, and intelligent metasurface technology. Therefore, even when there are obstructions between the transmitter and the user, and multiple passive eavesdroppers during transmission, a high security capacity can still be achieved. Additionally, the figure clearly shows that as the number of transmitting antennas increases, the system security capacity also increases. However, the increase in the number of antennas does not lead to an unlimited increase in security capacity; eventually, a certain security capacity value is reached and stabilizes.

[0121] This invention provides a non-line-of-sight physical layer secure transmission device 600, such as... Figure 6 The device shown includes: a guide vector establishment module 601, an analysis module 602, a vector calculation module 603, a projection matrix calculation module 604, and a signal transmission module 605.

[0122] The steering vector establishment module 601 is used to establish a smart metasurface-assisted frequency-controlled array system, and calculates the steering vectors of the transmitter to the desired user, the smart metasurface to the desired user, and the transmitter to the smart metasurface, based on the positions of the smart metasurface and the desired user relative to the transmitter. The steering vector establishment module 601 includes multiple frequency-controlled array antennas and a smart metasurface; the multiple frequency-controlled array antennas include multiple uniformly arranged transmitting antennas; the smart metasurface includes multiple reflecting elements.

[0123] Analysis module 602 is used to acquire and analyze the signals received by the desired user and the eavesdropper, and determine the analysis results. Analysis module 602 is used to calculate the signal received by the desired user as follows: in, This represents the transmitter's steering vector toward the desired user; This represents the guidance vector of the intelligent metasurface to the desired user; Let be an M-dimensional diagonal matrix, representing the reflection coefficient matrix of the intelligent metasurface, where θ m Let α represent the phase shift of the m-th reflecting element, and α∈(0,1] represent the amplitude reflection coefficient. This represents the guiding vector of the transmitter to the smart metasurface; The desired channel is represented by additive white Gaussian noise; the signal received by the eavesdropper is: in, This represents the transmitter's guidance vector towards the eavesdropper; This represents the guidance vector of the intelligent metasurface to the eavesdropper; This represents additive white Gaussian noise in the eavesdropping channel.

[0124] The vector calculation module 603 is used to design and calculate the emitted beamforming vector and the intelligent metasurface reflection coefficient matrix based on the analysis results.

[0125] The projection matrix calculation module 604 is used to calculate the artificial noise projection matrix. The constraint condition for the projection matrix calculation module 604 to calculate the artificial noise projection matrix is ​​that the artificial noise interferes with the eavesdropper without affecting the signal received by the desired user.

[0126] The signal transmission module 605 is used to transmit symbol information based on the transmitted beamforming vector, the smart metasurface reflection coefficient matrix, and the artificial noise projection matrix. The signal transmission module 605 designs and calculates the transmitted beamforming vector and the smart metasurface reflection coefficient matrix based on the analysis results, including the following constraints: the transmitted beamforming vector and the smart metasurface reflection coefficient matrix are designed using a method that maximizes the artificial noise interference frequency; the desired user power meets the minimum signal reception power so that the transmitted power of the artificial noise is maximized.

[0127] The apparatus or module described in the above embodiments can be implemented by a computer chip or physical entity, or by a product with a certain function. For ease of description, the above apparatus is described by dividing it into various modules according to their functions. In implementing this application, the functions of each module can be implemented in one or more software and / or hardware. Of course, a module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0128] This invention also provides a transmitter for non-line-of-sight physical layer secure transmission, such as... Figure 7 As shown, the transmitter includes a memory 701 and a processor 702; the memory 701 is used to store computer-executable instructions; the processor 702 is used to execute the computer-executable instructions to implement the non-line-of-sight physical layer secure transmission method described in the embodiments of the present invention.

[0129] This invention provides a computer-readable storage medium storing executable instructions. When a computer executes the executable instructions, it can implement the non-line-of-sight physical layer secure transmission method described above in this invention.

[0130] The aforementioned storage media include, but are not limited to, Random Access Memory (RAM), Read-Only Memory (ROM), Cache, Hard Disk Drive (HDD), or Memory Card. The memory can be used to store computer program instructions.

[0131] While this application provides the method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive labor. The order of steps listed in this embodiment is merely one possible execution order among many and does not represent the only possible execution order. In actual device or client product execution, the methods shown in this embodiment or the accompanying drawings can be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment).

[0132] The various embodiments described in this specification are presented in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. All or part of this application can be used in numerous general-purpose or special-purpose computer system environments or configurations. Examples include: personal computers, server computers, handheld or portable devices, tablet devices, mobile communication terminals, multiprocessor systems, microprocessor-based systems, programmable electronic devices, network PCs, minicomputers, mainframe computers, and distributed computing environments including any of the above systems or devices, etc.

[0133] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A non-line-of-sight physical layer secure transmission method, characterized in that, include: A frequency control array system assisted by a smart metasurface is established, and the guiding vector of the transmitter to the desired user, the guiding vector of the smart metasurface to the desired user, and the guiding vector of the transmitter to the smart metasurface are calculated according to the positions of the smart metasurface and the desired user relative to the transmitter, respectively. Acquire and analyze the signals received by the intended user and the eavesdropper, and determine the analysis results; Based on the analysis results, the emitted beamforming vector and the smart metasurface reflection coefficient matrix were designed and calculated, including the following constraints: The transmit beamforming vector and the intelligent metasurface reflection coefficient matrix are designed using a method that maximizes the artificial noise interference frequency; the desired user power satisfies the minimum signal reception power so that the transmit power of the artificial noise is maximized. Hypothesis vector The optimization problem is described as follows: ， in, Indicates the power of artificial noise emission; This represents a collection of intelligent metasurface reflective elements; This represents the minimum signal-to-interference-plus-noise ratio requirement for users to reliably receive signals. Represents the beamforming vector. for A diagonal matrix, denoted as , represents the reflection coefficient matrix of the intelligent metasurface, where Indicates the first Phase shift of each reflecting element Indicates the amplitude reflection coefficient; Calculate the artificial noise projection matrix, wherein the constraint condition for calculating the artificial noise projection matrix is ​​that the artificial noise interferes with the eavesdropper but does not affect the signal received by the desired user; This includes: The calculation formula is based on the principle of interfering with the eavesdropper with artificial noise without affecting the signal received by the intended user. The artificial noise projection matrix is ​​calculated using the following formula: ， in, Represents the projection matrix of artificial noise. This represents the transmitter's steering vector toward the desired user. This represents the guidance vector of the intelligent metasurface to the desired user. This represents the guiding vector of the transmitter to the smart metasurface; The symbol information is transmitted based on the transmitted beamforming vector, the intelligent metasurface reflection coefficient matrix, and the artificial noise projection matrix.

2. The method according to claim 1, characterized in that, The intelligent metasurface-assisted frequency control array system includes: a frequency control array antenna and an intelligent metasurface; The frequency-controlled array antenna includes multiple uniformly arranged transmitting antennas; The intelligent metasurface includes multiple reflective units.

3. The method according to claim 1, characterized in that, The signal that the user is expected to receive is: ， in, This represents the guidance vector of the transmitter towards the desired user; This represents the guidance vector of the intelligent metasurface to the desired user; for A diagonal matrix, denoted as , represents the reflection coefficient matrix of the intelligent metasurface, where Indicates the first Phase shift of each reflecting element Indicates the amplitude reflection coefficient; This represents the guiding vector of the transmitter to the smart metasurface; This represents additive white Gaussian noise in the desired channel. The signal received by the eavesdropper is: ， in, This represents the guidance vector of the transmitter towards the eavesdropper; This represents the guidance vector of the intelligent metasurface to the eavesdropper; The signal represents additive white Gaussian noise in the eavesdropping channel; s represents the transmitter's radiated signal vector. And the process of obtaining s is as follows: First, the transmitter performs phase modulation on the input bit stream to obtain modulation symbols. , It is a set of modulation symbols that meets the normalization condition, i.e. ; Subsequently, the modulation symbols are weighted and artificial noise is introduced to obtain the final radiated signal vector. ； In the formula: Indicates the power of artificial noise emission; Represents the beamforming vector, for modulation symbols Further processing was performed to match all transmitting antennas; ， in, Represents the projection matrix of artificial noise; This represents the vector of artificial noise, which follows a normal distribution.

4. A non-line-of-sight physical layer secure transmission device, characterized in that, include: The steering vector establishment module is used to establish a frequency control array system assisted by a smart metasurface, and calculate the steering vector of the transmitter to the desired user, the steering vector of the smart metasurface to the desired user, and the steering vector of the transmitter to the smart metasurface, respectively, based on the position of the smart metasurface and the desired user relative to the transmitter in the system. The analysis module is used to acquire and analyze the signals received by the intended user and the eavesdropper, and determine the analysis results; The vector calculation module is used to design and calculate the emitted beamforming vector and the intelligent metasurface reflection coefficient matrix based on the analysis results. The projection matrix calculation module is used to calculate the projection matrix of artificial noise; The signal transmission module is used to transmit symbol information according to the transmitted beamforming vector, the intelligent metasurface reflection coefficient matrix, and the artificial noise projection matrix; Based on the analysis results, the emitted beamforming vector and the smart metasurface reflection coefficient matrix were designed and calculated, including the following constraints: The transmit beamforming vector and the intelligent metasurface reflection coefficient matrix are designed using a method that maximizes the artificial noise interference frequency; the desired user power satisfies the minimum signal reception power so that the transmit power of the artificial noise is maximized. Hypothesis vector The optimization problem is described as follows: ， in, Indicates the power of artificial noise emission; This represents a collection of intelligent metasurface reflective elements; This represents the minimum signal-to-interference-plus-noise ratio requirement for users to reliably receive signals. Represents the beamforming vector. for A diagonal matrix, denoted as , represents the reflection coefficient matrix of the intelligent metasurface, where Indicates the first Phase shift of each reflecting element Indicates the amplitude reflection coefficient; The constraint condition for calculating the artificial noise projection matrix is ​​that the artificial noise interferes with the eavesdropper but does not affect the signal received by the desired user. This includes: The calculation formula is based on the principle of interfering with the eavesdropper with artificial noise without affecting the signal received by the intended user. The artificial noise projection matrix is ​​calculated using the following formula: ， in, Represents the projection matrix of artificial noise. This represents the transmitter's steering vector toward the desired user. This represents the array steering vector of the smart metasurface for the desired user. This represents the guiding vector of the transmitter to the smart metasurface.

5. A transmitter for non-line-of-sight physical layer secure transmission, characterized in that, Including memory and processor; The memory is used to store computer-executable instructions; The processor is configured to execute the computer-executable instructions to implement the method according to any one of claims 1-3.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores executable instructions, which, when executed by a computer, enable the implementation of the method as described in any one of claims 1-3.

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