Positioning method based on reconfigurable intelligent surface and reconfigurable holographic metasurface

Abstract

The application provides a positioning method based on a reconfigurable intelligent surface and a reconfigurable holographic metasurface, comprising: acquiring an actual reflection signal of a positioning target in a current period received by a receiver; determining an initial estimated position of the positioning target at a current moment based on the actual reflection signal in the current period; determining optimal parameters of the current period based on the initial estimated position of the positioning target at the current moment and a first expression; the first expression is determined by maximizing the ratio of the reflection signal to a preset noise; the optimal parameters of the current period include a phase shift of the reconfigurable intelligent surface and an amplitude of the reconfigurable holographic metasurface; and determining an estimated position of the positioning target in a period with the maximum signal-to-noise ratio as a final estimated position of the positioning target based on the optimal parameters of the current period and optimal parameters of other periods. Based on this, low-power consumption and low-cost radar positioning with high precision is realized by using a non-direct path channel.

Description

Technical Field

[0001] This invention relates to the field of artificial intelligence technology, and in particular to a positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces. Background Technology

[0002] With the development of 6G, the demand for positioning and sensing capabilities is further increasing. Radar uses electromagnetic waves to locate targets, is less affected by the external environment, and has wide applications in positioning. Existing high-precision radar positioning systems are mostly based on phased arrays, which have high power consumption and hardware costs. Furthermore, existing radars largely rely on direct-path channels, which do not always meet the requirements of direct-path positioning in practical applications. Non-direct-path signal-to-noise ratios are often lower, significantly impacting positioning performance. Therefore, how to utilize non-direct-path channels to achieve low-power, low-cost, and high-precision radar positioning is an urgent problem to be solved. Summary of the Invention

[0003] This invention provides a positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces, which utilizes non-direct path channels to achieve low power consumption, low cost, and high precision radar positioning.

[0004] This invention provides a positioning method based on a reconfigurable smart surface and a reconfigurable holographic metasurface, comprising: acquiring the actual reflected signal of a positioning target received by a receiver for the current period; the current period being one of at least one periods within a first preset time period; determining the initial estimated position of the positioning target at the current moment based on the actual reflected signal of the current period; determining the optimal parameters of the current period based on the initial estimated position of the positioning target at the current moment and a pre-determined first expression for solving the optimal parameters; the first expression being determined by maximizing the ratio of the reflected signal to a preset noise; the optimal parameters of the current period including the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface; redetermining the estimated position of the positioning target based on the optimal parameters of the current period, and determining the optimal parameters of other periods within the first preset time period based on the redetermined estimated position of the positioning target; determining the period with the highest signal-to-noise ratio based on the optimal parameters of the current period and the optimal parameters of the other periods, and determining the estimated position of the positioning target corresponding to the period with the highest signal-to-noise ratio as the final estimated position of the positioning target.

[0005] Based on any of the above embodiments, before determining the optimal parameters for the current period based on the initial estimated position of the positioning target at the current moment and the predetermined first expression for solving the optimal parameters, the method further includes: determining an optimization problem for solving the optimal parameters by maximizing a second expression for the ratio of the reflected signal to a preset noise, according to the constraints of the transmitted signal; solving the optimization problem to obtain the first expression for the optimal parameters.

[0006] Based on any of the above embodiments, the second expression for the ratio of the reflected signal to the preset noise is: Among them, ∫ T |r(ω,t)| 2 Let dt be the energy of the estimated signal r(ω,t) of the actual reflected signal at each time point within a period T. Preset noise within one period T The energy is given by β, which is the reflection coefficient of the target being located, and is a constant; μ is a coefficient related to the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface, E. x The energy of the first transmitted signal x from the feed source in the first reconfigurable holographic metasurface corresponding to the transmitter; The variance of the preset Gaussian noise distribution is given; the constraint condition for the transmitted signal is ∫ T |s(t)| 2 dt=E M Where s(t) is the second transmitted signal of the metamaterial array unit in the first reconfigurable holographic metasurface corresponding to the transmitter, E M The energy of the second transmitted signal is s(t); where s(t) = Q. D ψ D x, Q D Let ψ be the phase shift vector of the first reconfigurable holographic metasurface corresponding to the transmitter. D Let be the amplitude vector of the first reconfigurable holographic metasurface corresponding to the transmitter.

[0007] Based on any of the above embodiments, solving the optimization problem to obtain a first expression for the optimal parameters includes: approximating the second expression as a concave function near the parameter points in the previous iteration cycle based on Taylor expansion; wherein, the concave function is... Where, ζ m Let m be the m-th parameter among a plurality of parameters to be optimized; the parameters to be optimized include the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface; Let ζ be the parameter in the (i-1)th iteration based on the optimization parameters. i-1 The magnitude of the determined signal-to-noise ratio; This represents the m-th parameter among the parameters in the (i-1)-th iteration of the optimization parameters, where κ is a pre-defined non-negative constant; and ζi-1 =[ψ D,i-1 ,ψ U,i-1 ,θ D,i-1 ,θ U,i-1 ];ψ D,i-1 ψ represents the amplitude vector of the first reconfigurable holographic metasurface corresponding to the transmitter in the (i-1)th iteration of the optimized parameters. U,i-1 θ represents the amplitude vector of the reconfigurable holographic metasurface corresponding to the receiver in the (i-1)th iteration period of the optimized parameters. D,i-1 To optimize the phase shift vector of the smart surface transmitting a signal to the positioning target during the (i-1)th iteration of the parameters, θ U,i-1 To optimize the amplitude vector of the reflected signal received by the smart surface from the positioning target during the (i-1)th iteration of the parameter optimization, the first expression for solving the optimal parameters is obtained based on the concave function, where the first expression is: α is the preset step size.

[0008] Based on any of the above embodiments, before determining the initial estimated position of the positioning target at the current moment based on the actual reflected signal of the current period, the method further includes: substituting the actual reflected signal of at least one period within a second preset time period into a third expression of the log-likelihood function, and determining a preset maximum log-likelihood function based on maximum likelihood estimation; wherein, the third expression is: Where y(t) represents the actual reflected signal, r(ω,t) represents the estimated signal of the actual reflected signal at time t, and ω represents the estimated position parameters of the target at time t. The variance of the preset Gaussian noise distribution.

[0009] Based on any of the above embodiments, the step of redetermining the estimated position of the positioning target based on the optimal parameters of the current period, and determining the optimal parameters of other periods in at least one period within the first preset time period based on the redetermined estimated position of the positioning target, includes: adjusting the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface based on the optimal parameters of the current period; determining the estimated position of the positioning target at the next moment based on the adjusted phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface, the actual reflected signal of the positioning target in the next period of the current period received by the receiver, and a preset maximum log-likelihood function; and determining the optimal parameters at the next moment based on the estimated position of the positioning target at the next moment and a preset first expression for solving the optimal parameters.

[0010] Based on any of the above embodiments, before determining the initial estimated position of the positioning target at the current moment based on the actual reflected signal of the current period, the method further includes: determining a seventh expression of the third transmitted signal received by the positioning target based on a fourth expression of the second transmitted signal corresponding to the first reconfigurable holographic metasurface, a fifth expression of the first channel corresponding to the reconfigurable holographic metasurface to the reconfigurable smart surface, and a sixth expression of the second channel corresponding to the reconfigurable smart surface to the positioning target; and determining a tenth expression of the estimated signal of the reflected signal received by the receiver based on the seventh expression, an eighth expression of the first reflected signal from the positioning target to the reconfigurable smart surface, and a ninth expression of the second reflected signal corresponding to the second reconfigurable holographic metasurface.

[0011] This invention also provides a positioning system based on a reconfigurable smart surface and a reconfigurable holographic metasurface. The system includes: a reconfigurable smart surface, a transmitter, a receiver, a first reconfigurable holographic metasurface connected to the transmitter, a second reconfigurable holographic metasurface connected to the receiver, and a processor. The first reconfigurable holographic metasurface generates a second transmission signal with a specific waveform based on a first transmission signal generated by the transmitter. The second reconfigurable holographic metasurface receives a first reflected signal from the reconfigurable smart surface, converts the first reflected signal into a second reflected signal, and transmits the second reflected signal to the receiver. The reconfigurable smart surface receives the second transmission signal and adjusts the amplitude and phase shift of the second transmission signal to determine a third transmission signal. It also receives a third reflected signal from a positioning target, adjusts the amplitude and phase shift of the third reflected signal to determine a first reflected signal, and transmits the first reflected signal to the second reconfigurable holographic metasurface. The processor executes the aforementioned positioning method based on the reconfigurable smart surface and reconfigurable holographic metasurface.

[0012] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described above.

[0013] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described above.

[0014] The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention estimates the position of the target in cycles. By maximizing the signal-to-noise ratio (SNR), optimal parameters for the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface with optimal positioning accuracy are obtained in each cycle within a first preset time period. Based on the optimal parameters across all cycles, the estimated position of the target in the cycle with the highest SNR is determined as the final estimated position of the target. The entire process actively adjusts the parameters of the reconfigurable smart surface and the reconfigurable holographic metasurface, thereby actively adjusting the channel quality and improving positioning accuracy. Furthermore, since the positioning process utilizes a low-cost and low-power non-direct-path channel composed of the reconfigurable smart surface and the reconfigurable holographic metasurface, high-precision target positioning using a low-cost, low-power non-direct-path channel is achieved. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is one of the schematic diagrams of the positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by the present invention;

[0017] Figure 2 This is one of the flowcharts illustrating the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention.

[0018] Figure 3 This is the second flowchart illustrating the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention.

[0019] Figure 4 This is the third flowchart illustrating the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention.

[0020] Figure 5 This is the fourth flowchart illustrating the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention.

[0021] Figure 6 This is the second schematic diagram of the positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by the present invention;

[0022] Figure 7 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this 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 this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] To facilitate understanding, the technical terms involved in this invention will first be explained.

[0025] (1) Reconfigurable intelligent surface (RIS)

[0026] The reconfigurable smart surface consists of multiple identical RIS units. Within each RIS unit, multiple metal patches are connected by multiple PIN diodes and printed on a dielectric substrate. Each diode can be adjusted to two states: ON and OFF, resulting in different reflection coefficients for the RIS unit. Assume each RIS unit has N... s There are 10 different reflection coefficients, each with the same amplitude gain η and different phase shifts. s Three different phase shifts are uniformly distributed in the interval [0, 2π), with a spacing of π / 2. The reflection coefficient of the nth RIS unit can be expressed as: θ n =kΔθ,k∈{1,2,…,N s For simplicity, we can assume η = 1. The phase shift matrix of RIS is... Where θ = (θ1,…,θ) N ).

[0027] (2) Reconfigurable holographic surface (RHS)

[0028] A reconfigurable holographic metasurface (RSS) is a leaky-wave antenna that can generate specific waveforms by adjusting the amplitude of the leaky waves radiated from the metamaterial elements. The RHS consists of three parts: a waveguide, a feed source, and metamaterial array elements. When transmitting radar signals, the signal enters the waveguide through the feed source and then propagates to the metamaterial array elements embedded in the waveguide. Each metamaterial array element radiates the signal into free space in the form of a leaky wave. The amplitude of the radiated signal from each array element can be controlled by adjusting the states of multiple PIN diodes to obtain the desired waveform. Receiving signals with the RHS is the reverse process; that is, the metamaterial array elements transmit the received signal to the feed source. The RHS model is as follows:

[0029] Assuming the feed signal is x, the signal transmitted by the nth RHS array element can be expressed as:

[0030]

[0031] in, Let be the radiation amplitude of the nth array element. The phase shift of signal x as it propagates from the feed source to the nth array element is represented by γ, where γ is the refractive index of the waveguide, and d is the phase shift of the waveguide. n λ is the distance from the feed source to the nth array element, and λ is the carrier wavelength.

[0032] Accordingly, the signal transmitted by the transmitter RHS It can be represented as:

[0033] s = Q D ψ D x

[0034] in This is the amplitude vector of the transmitter's RHS.

[0035] Similarly, the RHS signal model at the receiving end is as follows: Assume the received signal is Where z n Let represent the signal received by the nth RHS array element. Then, the signal received by the receiver can be represented as:

[0036] y = (Q U ψ U ) T z

[0037] in It is the amplitude vector of the RHS at the receiving end. This represents the radiation amplitude of the nth array element.

[0038] To facilitate understanding, the inventive concept of this invention will be further elaborated.

[0039] To address the demands for high-precision, low-power positioning and sensing, radar is considered a promising technology. Existing radars mostly use phased arrays as antennas. A phased array is an array of multiple antenna elements. Signals are distributed to each antenna element via a power divider, and phase shifters adjust the phase shift of the signal at each antenna element. The signals radiated from all antenna elements are superimposed to form the desired waveform. Radar operates by emitting electromagnetic waves through its antennas, which are reflected by the target. The reflected electromagnetic waves are then received, and the target is detected and located by analyzing information such as the time delay and angle of arrival of the received signal. Phased array radar relies on phase shifters and power dividers, resulting in high power consumption and hardware costs. Therefore, high-precision phased array radar has significant power consumption and cost. Furthermore, most existing radar positioning schemes cannot actively control the quality of the propagation channel, but rather passively receive the channel quality. This causes the radar signal to attenuate significantly when the channel quality is poor, leading to a decline in positioning and sensing performance.

[0040] Reconfigurable holographic surfaces generate desired waveforms by adjusting the radiation amplitude of each radiating element. These elements are composed of simple diode-based circuits, resulting in a simple structure and lower power consumption. Reconfigurable smart surfaces can reconfigure the wireless propagation environment by controlling reflection. Therefore, this invention utilizes reconfigurable holographic surfaces and reconfigurable smart surfaces for assisted positioning, designing a high-precision radar positioning system. Reconfigurable holographic surfaces can replace phased arrays, featuring low power consumption and low cost. Reconfigurable smart surfaces can customize channels by changing the signal phase shift, improving the signal-to-noise ratio of the reflection path, thus enabling assisted positioning using non-direct paths. Therefore, the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces of this invention can reduce the power consumption and cost of radar positioning systems while improving radar system coverage.

[0041] The positioning method and system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces of the present invention are described below with reference to the accompanying drawings. For ease of understanding, [further details are provided]. Figure 1 The positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention will be described.

[0042] like Figure 1 As shown, the positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention includes a transmitter, a receiver, a reconfigurable smart surface, two reconfigurable holographic metasurfaces, and a radar target with an unknown location. In addition, the positioning system may also include a processor, which can be located in the transmitter or receiver, or in a remote server. The two RHSs are the RHS connected to the transmitter (also called the transmitting end RHS) and the RHS connected to the receiver (receiving end RHS). The L values ​​of the transmitter RHS and the transmitting end RHS are... r Each feed source is connected via Lr Each radio frequency link is connected separately. The receiver and the receiver RHS each have a feed source connected via L. r Each of the radio frequency links is connected. The transmitter RHS has a total of N t There are N radiating elements and the receiver RHS has a total of N r N radiating units. The reconfigurable smart surface has N RIS units.

[0043] Assuming the target is located in the far field of the RHS and RIS, the propagating signal can be assumed to be a plane wave. Assuming the RHS and RIS are close to each other, the target's relative orientation to any RIS and RHS cell can be considered the same. A coordinate axis is established with the transmitter and receiver locations as the origin, the positions of the RIS and RHS are known, and the target's position is unknown.

[0044] The radar positioning scenario is as follows: only non-direct path channels are considered. The transmitter RHS emits a signal, which reaches the target via the reflection path through the RIS. The target reflects the signal and then reaches the receiver RHS via the reflection path through the RIS.

[0045] Figure 2 This is one of the flowcharts illustrating the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by the present invention. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces can be executed by a processor in the positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces. Figure 2 As shown, the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention includes the following steps:

[0046] Step 210: Obtain the actual reflected signal of the current period of the positioning target received by the receiver.

[0047] The current period is one of at least one periods within a first preset time period.

[0048] Understandably, to facilitate the subsequent active adjustment of channel quality by the reconfigurable smart surface and reconfigurable holographic metasurface, thereby improving the estimation accuracy of the positioning target, this invention employs a periodic approach to estimate the position of the positioning target. In other words, the position of the positioning target can be estimated in multiple periods over a given time period to gradually determine the optimal parameters of the reconfigurable smart surface and reconfigurable holographic metasurface, thus improving the estimation accuracy of the positioning target.

[0049] Step 220: Based on the actual reflected signal of the current period, determine the initial estimated position of the positioning target at the current moment.

[0050] The actual reflected signal for the current period is the actual reflected signal at the RHS feed of the transmitter for the current period.

[0051] Specifically, the initial estimated position of the target at the current moment can be determined based on the actual reflected signal of the current period and a preset maximum log-likelihood function. The preset maximum log-likelihood function is determined based on the actual reflected signal of at least one period within a second preset time period. The second preset time period is a preset historical time period.

[0052] It is understandable that the preset maximum log-likelihood function is used to estimate the estimated position of the target, and therefore, it can be determined based on the actual reflected signal of at least one cycle within the second preset time period. Specifically, the process for determining the preset maximum log-likelihood function can be referred to the relevant process described later.

[0053] Step 230: Based on the initial estimated position of the positioning target at the current moment and the first expression for solving the optimal parameters, determine the optimal parameters for the current period; the first expression is determined by maximizing the ratio of the reflected signal to the preset noise; the optimal parameters for the current period include the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface.

[0054] In this system, the ratio of the reflected signal to the preset noise is the signal-to-noise ratio (SNR) of the signal received by the receiver. The positioning accuracy of the target is positively correlated with the SNR of the received signal; that is, the higher the ratio of the reflected signal to the preset noise, the higher the positioning accuracy. Therefore, by maximizing the ratio of the reflected signal to the preset noise, the first expression for solving the optimal parameters is determined, ensuring that the optimal parameters are those with the best positioning accuracy. This prepares for more accurate positioning in the next cycle based on the optimal parameters of the current cycle. Simultaneously, by optimizing the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface, the positioning accuracy of the positioning system based on the reconfigurable smart surface and reconfigurable holographic metasurface is continuously improved, thereby enhancing the positioning accuracy of non-direct path channels. Furthermore, since the reconfigurable smart surface and reconfigurable holographic metasurface used in this invention have low costs, the positioning accuracy of the radar system is improved while reducing its power consumption and cost.

[0055] Step 240: Based on the optimal parameters of the current period, redetermine the estimated position of the positioning target, and based on the redetermined estimated position of the positioning target, determine the optimal parameters of other periods in at least one period within the first preset time period.

[0056] As mentioned earlier, to facilitate the subsequent active adjustment of channel quality by the reconfigurable smart surface and reconfigurable holographic metasurface, thereby improving the estimation accuracy of the positioning target, this invention employs periodic estimation of the positioning target's position. Therefore, after determining the optimal parameters for the current period, based on steps similar to steps 210 to 230 above, and based on the re-determined estimated position of the positioning target, the optimal parameters for other periods within at least one period of the first preset time period can be determined. This prepares for subsequently determining the estimated position of the positioning target corresponding to the optimal parameter with the highest positioning accuracy from the optimal parameters of all periods.

[0057] Step 250: Based on the optimal parameters of the current period and the optimal parameters of the other periods, determine the period with the highest signal-to-noise ratio, and determine the estimated position of the positioning target corresponding to the period with the highest signal-to-noise ratio as the final estimated position of the positioning target.

[0058] As mentioned earlier, the optimal parameter is determined by maximizing the ratio of the reflected signal to the preset noise. This ratio reflects the positioning accuracy; the higher the ratio, the higher the positioning accuracy. Therefore, based on at least one optimal parameter determined for each period of the first preset time period, the period with the highest signal-to-noise ratio can be determined, and the estimated position of the positioning target corresponding to the period with the highest signal-to-noise ratio can be determined as the final estimated position of the positioning target.

[0059] The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention estimates the position of the target in cycles. By maximizing the signal-to-noise ratio (SNR), optimal parameters for the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface with optimal positioning accuracy are obtained in each cycle within a first preset time period. Based on the optimal parameters across all cycles, the estimated position of the target in the cycle with the highest SNR is determined as the final estimated position of the target. The entire process actively adjusts the parameters of the reconfigurable smart surface and the reconfigurable holographic metasurface, thereby actively adjusting the channel quality and improving positioning accuracy. Furthermore, since the positioning process utilizes a low-cost and low-power non-direct-path channel composed of the reconfigurable smart surface and the reconfigurable holographic metasurface, high-precision target positioning using a low-cost, low-power non-direct-path channel is achieved.

[0060] It is understood that, in one embodiment, such as Figure 3 As shown, before determining the optimal parameters for the current period based on the initial estimated position of the positioning target at the current moment and the pre-determined first expression for solving the optimal parameters, the method further includes:

[0061] Step 310: By using the second expression that maximizes the ratio of the reflected signal to the preset noise, the optimization problem of solving the optimal parameters is determined according to the constraints of the transmitted signal.

[0062] The ratio of the reflected signal to the preset noise can be the ratio of the energy of the reflected signal to the energy of the preset noise. Therefore, in one embodiment, the second expression for the ratio of the reflected signal to the preset noise is: Among them, ∫ T |r(ω,t)| 2 Let dt be the energy of the estimated signal r(ω,t) of the actual reflected signal at each time point within a period T. Preset noise within one period T The energy is given by β, which is the reflection coefficient of the target being located, and is a constant; μ is a coefficient related to the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface, E. x The energy of the first transmitted signal x from the feed source in the first reconfigurable holographic metasurface corresponding to the transmitter; The variance of the preset Gaussian noise distribution;

[0063] The constraint condition for the transmitted signal is ∫ T |s(t)| 2 dt=E M Where s(t) is the second transmitted signal of the metamaterial array unit in the first reconfigurable holographic metasurface corresponding to the transmitter, E M The energy of the second transmitted signal is s(t); where s(t) = Q. 2 ψ D x, Q D Let ψ be the phase shift vector of the first reconfigurable holographic metasurface corresponding to the transmitter. D Let be the amplitude vector of the first reconfigurable holographic metasurface corresponding to the transmitter.

[0064] It can be understood that by maximizing the ratio Γ of the reflected signal to the preset noise, and using the constraint condition of the transmitted signal as the constraint condition, the optimization problem of the optimal parameters of the phase shift of the reconstructed smart surface and the amplitude of the reconstructable holographic metasurface can be determined.

[0065] Step 320: Solve the optimization problem to obtain the first expression for the optimal parameters.

[0066] It is understandable that, in order to better solve the above optimization problem, the second expression can be approximated as a concave function. Specifically, Γ can be approximated using a Taylor expansion.

[0067] Therefore, in one embodiment, step 320 may include steps 3201 and 3202.

[0068] Step 3201: Based on Taylor expansion, the second expression is approximated as a concave function near the parameter point in the previous iteration cycle.

[0069] Wherein, the concave function is Where, ζ m Let m be the m-th parameter among a plurality of parameters to be optimized; the parameters to be optimized include the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface; Let ζ be the parameter in the (i-1)th iteration based on the optimization parameters. i-1 The magnitude of the determined signal-to-noise ratio; This represents the m-th parameter among the parameters in the (i-1)-th iteration of the optimization parameters, where κ is a pre-defined non-negative constant; and ζ i-1 =[ψ D,i-1 ,ψ U,i-1 ,θ D,i-1 ,θ U,i-1 ];ψ D,i-1 ψ represents the amplitude vector of the first reconfigurable holographic metasurface corresponding to the transmitter in the (i-1)th iteration of the optimized parameters. U,i-1 θ represents the amplitude vector of the reconfigurable holographic metasurface corresponding to the receiver in the (i-1)th iteration period of the optimized parameters. D,i-1 To optimize the phase shift vector of the smart surface transmitting a signal to the positioning target during the (i-1)th iteration of the parameters, θ U,i-1 In order to optimize the parameters, the amplitude vector of the smart surface receiving the reflected signal of the positioning target can be reconstructed in the (i-1)th iteration period.

[0070] It is understandable that the first two terms of a concave function... This can be understood as an approximation of Γ.

[0071] It can also be understood that the optimal solution is found by iteratively searching through multiple iteration cycles. When , the iteration stops. Here, ∈ is a pre-defined threshold value.

[0072] Step 3202: Based on the concave function, obtain the first expression for solving the optimal parameters.

[0073] It is understandable that in the above optimization problem, only the coefficient μ, which is related to the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface, is an unknown parameter. Therefore, the coefficient μ can be obtained by solving the above optimization problem. Specifically, referring to step 420 below, it can be seen that μ and ζ... c =[ψ D,c ,ψ U,c ,θ D,c ,θ U,c That is, to determine ζm Thus, the first expression for the optimal parameters can be determined.

[0074] Specifically, the first expression is: α is the preset step size.

[0075] In one embodiment, before determining the initial estimated position of the target at the current moment based on the actual reflected signal of the current period, the method further includes:

[0076] Substitute the actual reflected signal of at least one cycle within the second preset time period into the third expression of the log-likelihood function, and determine the preset maximum log-likelihood function based on the maximum likelihood estimation.

[0077] The third expression is: Where y(t) represents the actual reflected signal, r(ω,t) represents the estimated signal of the actual reflected signal at time t, and ω represents the estimated position parameters of the target at time t. Let the variance of the pre-defined Gaussian noise distribution be used. Therefore, based on maximum likelihood estimation, i.e., through... Find the estimated position parameters of the target that maximize L(y|ω). This allows us to obtain an expression for r(ω,t), which further facilitates determining the estimated position of the target given the actual reflected signal y(t).

[0078] It's understandable, combined Figure 1 As can be seen, the transmitter RHS sends out a signal, which reaches the target through the reflection path of the RIS. The target reflects the signal and then reaches the receiver RHS through the reflection path of the RIS. Therefore, the expression in r(ω,t) in the third expression above can be determined based on the information corresponding to the reconfigurable smart surface and the reconfigurable holographic metasurface.

[0079] Therefore, in one embodiment, such as Figure 4 As shown, before determining the initial estimated position of the target at the current moment based on the actual reflected signal of the current period, the method further includes steps 410 and 420.

[0080] Step 410: Based on the fourth expression of the second transmitted signal corresponding to the first reconfigurable holographic metasurface, the fifth expression of the first channel corresponding to the reconfigurable holographic metasurface to the reconfigurable smart surface, and the sixth expression of the second channel corresponding to the reconfigurable smart surface to the positioning target, determine the seventh expression of the third transmitted signal received by the positioning target.

[0081] Combination Figure 1The second emission signal corresponding to the first reconfigurable holographic metasurface is the second emission signal corresponding to the metamaterial array unit in the first reconfigurable holographic metasurface. Therefore, its corresponding fourth expression is: s = Q D ψ D x; where Q D ψ represents the phase shift vector of the first reconfigurable holographic metasurface; t denoted as the amplitude vector of the first reconfigurable holographic metasurface; x represents the first emission signal of the feed source in the first reconfigurable holographic metasurface; q n This represents the phase shift that occurs during propagation from the feed source to the nth metamaterial array element. d n γ is the distance from the feed source to the nth array element, γ is the refractive index of the waveguide, and λ is the carrier wavelength; Let represent the amplitude vector of the first reconfigurable holographic metasurface, and be the parameters to be optimized;

[0082] The fifth expression is: h m, Let represent the channel from the nth array element of the reconfigurable holographic metasurface to the mth reconfigurable smart surface element of the reconfigurable smart surface, where The gain of the nth array element of the reconfigurable holographic metasurface. The relative direction from the nth array element to the mth reconfigurable smart surface element. The relative values ​​of the nth array element and the mth reconfigurable smart surface element are respectively Normalized radiation pattern in direction, S e For the area of ​​a reconfigurable smart surface cell, l m, Let λ be the distance from the nth array unit of the reconfigurable holographic metasurface to the mth reconfigurable smart surface unit of the reconfigurable smart surface, and let λ be the carrier wavelength.

[0083] The normalized radiation pattern is the result of normalizing the radiation field using the maximum radiation field value; that is, the ratio of the magnitude of the radiation field in this direction to the maximum radiation field. The radiation pattern expresses the change in power radiated or received by the antenna or reflector as a function of distance from its direction, making it easy to visually identify the location of maximum transmitted or received power. An example of a normalized radiation pattern is as follows:

[0084]

[0085] The sixth expression is: b(θ) = aR(θ)H, where a represents the guidance vector of the reconfigurable smart surface relative to the target, R(θ) represents the phase shift matrix of the reconfigurable smart surface, and H = [h m,], θ N =kΔθ,k∈{1,2,…,N s}, N s Let a = (a1, ..., a2) be the number of phase shifts in the reconfigurable smart surface. m a N ), a1 represents the guidance vector of the first RIS unit in the reconfigurable smart surface relative to the target. m This represents the guidance vector of the m-th RIS unit in the reconfigurable smart surface relative to the target. Similarly, a N Let G represent the guidance vector of the Nth RIS unit in the reconfigurable smart surface relative to the target; where G R For the gain of reconfigurable smart surface cells, express Let k be the wave vector pointing towards the target, where k represents the direction of the target. It is the relative position of the m-th reconfigurable smart surface unit relative to the 1st reconfigurable smart surface unit.

[0086] Regarding h m, The fifth expression is taken as H, and the fourth expression about s, s = Q, is taken as Q. D ψ D x, and the sixth expression for b(θ) b(θ)=aR(θ)H, substituting into the corresponding v=b(θ) D From )s+noise, we can obtain the seventh expression as: v=b(θ D )s+noise=b(θ D )Q D ψ D x + noise = aR(θ) D HQ D ψ D x+noise, where noise represents the signal strength. This means calculating the transmitted signal received by the target after it travels through the transmitter RHS, then through the RIS reflection path, and finally reaches the target.

[0087] It is understandable that, in order to distinguish between downlink (from the transmitter to the target) and uplink (from the transmitter to the target) channels, the superscript D is used to represent the parameters corresponding to the downlink channel, and the superscript U is used to represent the parameters corresponding to the uplink channel, such as θ. D θ represents the phase shift of the reconfigurable smart surface from the point where the transmitted signal travels to the target location. U This indicates the phase shift of the reconfigurable smart surface when it emits a second reflected signal to the second reconfigurable holographic metasurface.

[0088] Step 420: Based on the seventh expression, the eighth expression for the first reflection signal of the positioning target to the reconfigurable smart surface, and the ninth expression for the second reflection signal corresponding to the second reconfigurable holographic metasurface, determine the tenth expression for the estimated signal of the reflected signal received by the receiver.

[0089] It can be understood that the process of the positioning target returning the reflected signal to the receiving end RHS is the reverse process of the transmitted signal traveling from the transmitting end RHS through the RIS and finally reaching the positioning target. That is, the positioning target determines the reflected signal based on the transmitted signal received by the positioning target, and the reflected signal travels through the RIS and reaches the receiving end RHS. Therefore, based on step 420, the tenth expression of the estimated signal of the reflected signal received by the receiver can be determined.

[0090] The eighth expression is: z = b T (θ U )βv, where θ U Let b be the phase shift of the reconfigurable smart surface when it emits a second reflected signal to the second reconfigurable holographic metasurface, and let b be the parameter to be optimized. T (θ U ) is b(θ U ) is the transpose of ), where T represents the transpose and β is the reflection coefficient of the target.

[0091] The seventh expression v = b(θ) D )Q D ψ D x + noise and the eighth expression z = b T (θ U Substituting βv into the ninth expression yields: Thus obtain

[0092]

[0093] Therefore, the corresponding tenth expression is: r(ω)=βμx, It is understandable that, combining the formula for Q mentioned earlier, the refractive index γ of the waveguide, and the distance D from the feed source to the nth array element... n Given a fixed carrier wavelength λ, the corresponding Q D And Q U It can be calculated using the Q formula, therefore, where μ is related to ψ. U θ U θ D and ψ D Correlation coefficient, ψ U θ U θ D and ψ D Any one of them is the parameter ζ to be solved. mAmong them, ψ U θ U θ represents the amplitude of the reconfigurable holographic metasurface and the phase shift of the reconfigurable smart surface during the uplink transmission of the reflected signal. D and ψ D These represent the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface during downlink transmission of the transmitted signal, respectively. Let be the residual terms of noise and interference in the environment. For simplicity, assume that the residual terms of noise and interference in the environment follow a complex Gaussian distribution with a mean of 0 and a variance of .

[0094] In one embodiment, such as Figure 5 As shown, the step of redetermining the estimated position of the positioning target based on the optimal parameters of the current period, and determining the optimal parameters of other periods within at least one period of the first preset time period based on the redetermined estimated position of the positioning target, includes:

[0095] Step 510: Based on the optimal parameters of the current period, adjust the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface.

[0096] Among them, the optimal parameters for the current period include the amplitude ψ of the reconfigurable holographic metasurface during the uplink transmission of the reflected signal. U Phase shift θ of reconfigurable smart surfaces U And the phase shift θ of the reconfigurable smart surface during downlink transmission of the transmitted signal. D and the amplitude ψ of the reconfigurable holographic metasurface D Therefore, the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface can be adjusted based on the optimal parameters of the current period.

[0097] Step 520: Based on the phase shift of the adjusted reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface, the actual reflected signal of the next period of the current period of the positioning target received by the receiver, and the preset maximum log-likelihood function, determine the estimated position of the positioning target at the next moment.

[0098] It is understandable that this step is similar to the process of determining the initial estimated position of the target at the current moment based on the actual reflected signal of the current period, as mentioned above. For the sake of brevity, it will not be described in detail here.

[0099] Step 530: Based on the estimated position of the positioning target at the next moment and the predetermined first expression for solving the optimal parameters, determine the optimal parameters for the next moment.

[0100] It is understandable that this step is similar to step 230 mentioned above, and for the sake of brevity, it will not be repeated here.

[0101] It can be understood that steps 510 to 530 above are iterative processes. Based on steps 510 to 530 above, the optimal parameters of other cycles in at least one cycle within the first preset time period can be determined.

[0102] The positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by this invention will be described below. The positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces described below can be referred to in correspondence with the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces described above.

[0103] Figure 6 This is a schematic diagram of the positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by the present invention, as shown below. Figure 6 As shown, the positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided in this embodiment of the invention includes:

[0104] The radar positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by the present invention includes: a reconfigurable smart surface 610, a transmitter 620, a receiver 630, a first reconfigurable holographic metasurface 640 connected to the transmitter 620, a second reconfigurable holographic metasurface 650 connected to the receiver 630, and a processor 660.

[0105] Wherein, the first reconfigurable holographic metasurface 640 is used to generate a second transmission signal with a specific waveform based on the first transmission signal generated by the transmitter 620; the second reconfigurable holographic metasurface 650 is used to receive a first reflection signal from the reconfigurable smart surface 610, convert the first reflection signal into a second reflection signal, and send the second reflection signal to the receiver 630.

[0106] The reconfigurable smart surface 610 is used to receive the second transmitted signal and to adjust the amplitude and phase shift of the second transmitted information to determine the third transmitted signal; it is also used to receive the third reflected signal from the positioning target; and to adjust the amplitude and phase shift of the third reflected signal to determine the first reflected signal, and to send the first reflected signal to the second reconfigurable holographic metasurface 650.

[0107] The processor 660 is used to execute the above-described positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces.

[0108] It is understood that the aforementioned processor 660 can be located in the receiver 630.

[0109] The positioning system based on a reconfigurable smart surface and a reconfigurable holographic metasurface provided by this invention estimates the position of the target in cycles. By maximizing the signal-to-noise ratio (SNR), it obtains the optimal parameters for the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface with optimal positioning accuracy in each cycle within a first preset time period. Based on the optimal parameters across all cycles, the estimated position of the target in the cycle with the highest SNR is determined as the final estimated position of the target. The entire process actively adjusts the parameters of the reconfigurable smart surface and the reconfigurable holographic metasurface, thereby actively adjusting the channel quality and improving positioning accuracy. Furthermore, since the positioning process utilizes a low-cost and low-power indirect-path channel composed of the reconfigurable smart surface and the reconfigurable holographic metasurface, it achieves high-precision target positioning using a low-cost, low-power indirect-path channel.

[0110] Figure 7 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 7 As shown, the electronic device may include a processor 710, a communications interface 720, a memory 730, and a communication bus 740. The processor 710, communications interface 720, and memory 730 communicate with each other via the communication bus 740. The processor 710 can call logical instructions from the memory 730 to execute a positioning method based on a reconfigurable smart surface and a reconfigurable holographic metasurface. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces includes: acquiring the actual reflected signal of the positioning target in the current period received by the receiver; the current period is one of at least one periods within a first preset time period; determining the initial estimated position of the positioning target at the current moment based on the actual reflected signal of the current period; determining the optimal parameters of the current period based on the initial estimated position of the positioning target at the current moment and a pre-determined first expression for solving the optimal parameters; the first expression is determined by maximizing the ratio of the reflected signal to a preset noise; the optimal parameters of the current period include the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface; redetermining the estimated position of the positioning target based on the optimal parameters of the current period, and determining the optimal parameters of other periods within the first preset time period based on the redetermined estimated position of the positioning target; determining the period with the highest signal-to-noise ratio based on the optimal parameters of the current period and the optimal parameters of the other periods, and determining the estimated position of the positioning target corresponding to the period with the highest signal-to-noise ratio as the final estimated position of the positioning target.

[0111] Furthermore, the logical instructions in the aforementioned memory 730 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0112] On the other hand, the present invention also provides a computer program product, the computer program product including a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, and when the program instructions are executed by a computer, the computer is able to execute the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by the present invention. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces includes: acquiring the actual reflected signal of the positioning target in the current period received by the receiver; the current period is one of at least one periods within a first preset time period; determining the initial estimated position of the positioning target at the current moment based on the actual reflected signal of the current period; determining the optimal parameters of the current period based on the initial estimated position of the positioning target at the current moment and a pre-determined first expression for solving the optimal parameters; the first expression is determined by maximizing the ratio of the reflected signal to a preset noise; the optimal parameters of the current period include the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface; redetermining the estimated position of the positioning target based on the optimal parameters of the current period, and determining the optimal parameters of other periods within the first preset time period based on the redetermined estimated position of the positioning target; determining the period with the highest signal-to-noise ratio based on the optimal parameters of the current period and the optimal parameters of the other periods, and determining the estimated position of the positioning target corresponding to the period with the highest signal-to-noise ratio as the final estimated position of the positioning target.

[0113] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces provided by the present invention. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces includes: acquiring the actual reflected signal of the positioning target in the current period received by the receiver; the current period is one of at least one periods within a first preset time period; determining the initial estimated position of the positioning target at the current moment based on the actual reflected signal of the current period; determining the optimal parameters of the current period based on the initial estimated position of the positioning target at the current moment and a pre-determined first expression for solving the optimal parameters; the first expression is determined by maximizing the ratio of the reflected signal to a preset noise; the optimal parameters of the current period include the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface; redetermining the estimated position of the positioning target based on the optimal parameters of the current period, and determining the optimal parameters of other periods within the first preset time period based on the redetermined estimated position of the positioning target; determining the period with the highest signal-to-noise ratio based on the optimal parameters of the current period and the optimal parameters of the other periods, and determining the estimated position of the positioning target corresponding to the period with the highest signal-to-noise ratio as the final estimated position of the positioning target.

[0114] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0115] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0116] It is understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces, characterized in that, The method includes: The receiver receives the actual reflected signal of the positioning target during the current period; the current period is one of at least one period within a first preset time period. Based on the actual reflected signal of the current period, determine the initial estimated position of the target at the current moment; Based on the initial estimated position of the positioning target at the current moment and the first expression for solving the optimal parameters, the optimal parameters for the current period are determined; the first expression is determined by maximizing the ratio of the reflected signal to the preset noise; the optimal parameters for the current period include the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface. Based on the optimal parameters of the current period, the estimated position of the positioning target is re-determined, and based on the re-determined estimated position of the positioning target, the optimal parameters of other periods in at least one period within the first preset time period are determined. Based on the optimal parameters of the current period and the optimal parameters of the other periods, the period with the highest signal-to-noise ratio is determined, and the estimated position of the positioning target corresponding to the period with the highest signal-to-noise ratio is determined as the final estimated position of the positioning target.

2. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in claim 1, characterized in that, Before determining the optimal parameters for the current period based on the initial estimated position of the positioning target at the current moment and the pre-determined first expression for solving the optimal parameters, the method further includes: By using a second expression that maximizes the ratio of the reflected signal to the preset noise, and based on the constraints of the transmitted signal, the optimization problem of solving for the optimal parameters is determined. Solve the optimization problem to obtain the first expression for the optimal parameters.

3. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in claim 2, characterized in that, The second expression for the ratio of the reflected signal to the preset noise is: ,in, The estimated signal of the actual reflected signal at each time point within a period T. energy, Preset noise within one period T The energy of , where β is the reflection coefficient of the target being located, and is a constant; The coefficients are related to the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface. The energy of the first transmitted signal x from the feed source in the first reconfigurable holographic metasurface corresponding to the transmitter; The variance of the preset Gaussian noise distribution; The constraint condition for the transmitted signal is: , where s( () represents the second transmitted signal of the metamaterial array unit in the first reconfigurable holographic metasurface corresponding to the transmitter. The energy of the second transmitted signal; wherein, , Let be the phase shift vector of the first reconfigurable holographic metasurface corresponding to the transmitter. Let be the amplitude vector of the first reconfigurable holographic metasurface corresponding to the transmitter.

4. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in claim 3, characterized in that, Solving the optimization problem to obtain the first expression for the optimal parameters includes: Based on Taylor expansion, the second expression is approximated as a concave function near the parameter points in the previous iteration cycle; wherein, the concave function is... ,in, Let m be the m-th parameter among a plurality of parameters to be optimized; the parameters to be optimized include the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface; The parameters are based on the (i-1)th iteration of the optimization parameters. The magnitude of the determined signal-to-noise ratio; This represents the m-th parameter among the parameters in the (i-1)-th iteration of the optimization parameters. Let be a pre-defined nonnegative constant; where, ; Let represent the amplitude vector of the first reconfigurable holographic metasurface corresponding to the transmitter in the (i-1)th iteration of the optimized parameters. Let represent the amplitude vector of the reconstructable holographic metasurface corresponding to the receiver in the (i-1)th iteration of the optimized parameters. To optimize the parameters, the phase shift vector of the smart surface transmitting a signal to the positioning target can be reconstructed in the (i-1)th iteration cycle. In order to optimize the parameters, the amplitude vector of the smart surface receiving the reflected signal of the positioning target can be reconstructed in the (i-1)th iteration period; Based on the concave function, the first expression for solving the optimal parameters is obtained, wherein the first expression is: , , This is the preset step size.

5. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in claim 1, characterized in that, Before determining the initial estimated position of the target at the current moment based on the actual reflected signal of the current period, the method further includes: Substitute the actual reflected signal of at least one cycle within the second preset time period into the third expression of the log-likelihood function, and determine the preset maximum log-likelihood function based on the maximum likelihood estimation. The third expression is: ,in, Indicates the actual reflected signal. Indicates to The estimated signal of the actual reflected signal at time [time]. express Estimated position parameters of the target at all times. The variance of the preset Gaussian noise distribution.

6. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in claim 1, characterized in that, The step of redetermining the estimated location of the positioning target based on the optimal parameters of the current period, and determining the optimal parameters of other periods within at least one period of the first preset time period based on the redetermined estimated location of the positioning target, includes: Based on the optimal parameters of the current period, adjust the phase shift of the reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface; Based on the phase shift of the adjusted reconfigurable smart surface and the amplitude of the reconfigurable holographic metasurface, the actual reflected signal of the target in the next period of the current period received by the receiver, and the preset maximum log-likelihood function, the estimated position of the target at the next moment is determined. Based on the estimated position of the target at the next moment and the predetermined first expression for solving the optimal parameters, the optimal parameters at the next moment are determined.

7. The positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in claim 1, characterized in that, Before determining the initial estimated position of the target at the current moment based on the actual reflected signal of the current period, the method further includes: Based on the fourth expression of the second transmitted signal corresponding to the first reconfigurable holographic metasurface, the fifth expression of the first channel corresponding to the reconfigurable holographic metasurface to the reconfigurable smart surface, and the sixth expression of the second channel corresponding to the reconfigurable smart surface to the positioning target, the seventh expression of the third transmitted signal received by the positioning target is determined. Based on the seventh expression, the eighth expression for the first reflection signal of the positioning target to the reconfigurable smart surface, and the ninth expression for the second reflection signal corresponding to the second reconfigurable holographic metasurface, the tenth expression for the estimated signal of the reflected signal received by the receiver is determined.

8. A radar positioning system based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces, characterized in that, The system includes: a reconfigurable smart surface, a transmitter, a receiver, a first reconfigurable holographic metasurface connected to the transmitter, a second reconfigurable holographic metasurface connected to the receiver, and a processor; Wherein, the first reconfigurable holographic metasurface is used to generate a second transmission signal with a specific waveform based on a first transmission signal generated by the transmitter; the second reconfigurable holographic metasurface is used to receive a first reflection signal from the reconfigurable smart surface, convert the first reflection signal into a second reflection signal, and send the second reflection signal to the receiver; The reconfigurable smart surface is used to receive the second transmitted signal and to adjust the amplitude and phase shift of the second transmitted information to determine the third transmitted signal; it is also used to receive the third reflected signal from the positioning target; and to adjust the amplitude and phase shift of the third reflected signal to determine the first reflected signal, and to send the first reflected signal to the second reconfigurable holographic metasurface. The processor is used to execute the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in any one of claims 1 to 7.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the positioning method based on reconfigurable smart surfaces and reconfigurable holographic metasurfaces as described in any one of claims 1 to 7.

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