A method for evaluating performance of evaporation duct over-the-horizon communication based on RIS assistance

Abstract

The application relates to the field of waveguide propagation technology and discloses an evaporation waveguide over-the-horizon communication performance evaluation method based on RIS assistance, which comprises the following steps: constructing an atmospheric refractive index profile according to meteorological parameters of an evaporation waveguide environment containing an intelligent metasurface; modeling the intelligent metasurface as a generalized impedance boundary according to the spatial position, reflection characteristics and controllable phase response of the intelligent metasurface in the evaporation waveguide environment; stripping the fast-varying phase of electromagnetic waves in the evaporation waveguide environment on the generalized impedance boundary to obtain an auxiliary function and performing backward difference processing; based on a discrete mixed Fourier transform iteration method, performing backward difference solving on the slow-varying envelope field of electromagnetic waves in the vertical direction of the evaporation waveguide environment through the processed auxiliary function, and correcting the slow-varying envelope field through atmospheric refraction phase of the atmospheric refractive index profile to obtain a target slow-varying envelope field; and establishing a parabolic equation model of the evaporation waveguide environment to evaluate the over-the-horizon communication performance of the evaporation waveguide environment.

Description

Technical Field

[0001] This invention relates to the field of waveguide propagation technology, and in particular to a method, system, device and medium for evaluating the performance of evaporative waveguide beyond-line-of-sight communication based on RIS assistance. Background Technology

[0002] With the rapid growth in demand for marine information technology and long-range communication, evaporative waveguides, as a typical tropospheric waveguide structure at sea, can achieve beyond-line-of-sight propagation of electromagnetic waves, providing a natural channel advantage for long-distance communication and radar detection. Meanwhile, reconfigurable intelligent surfaces (RIS), as a novel passive control technology, can dynamically control the phase and propagation direction of electromagnetic waves by deploying a large number of low-cost programmable meta-atoms on a plane. This allows for intelligent signal enhancement and coverage optimization without complex radio frequency links, demonstrating significant advantages in improving communication capacity, expanding coverage, and reducing energy consumption.

[0003] Specifically, in evaporating waveguide environments, the reflection of electromagnetic waves at the upper boundary of the waveguide layer is a non-ideal total internal reflection at the interface of the gradient medium. Each reflection is accompanied by significant leakage mode loss and atmospheric scattering loss, and the cumulative loss from multiple reflections during long-distance propagation severely degrades communication performance. RIS, as an artificial passive metasurface, exhibits near-ideal controllable specular reflection, with extremely low single-reflection loss and no leakage mode loss. Introducing RIS into evaporating waveguide beyond-line-of-sight communication scenarios, replacing the high-loss multiple reflections of the waveguide layer with low-loss RIS reflection, and combining this with phase modulation to reconstruct the propagation path, can significantly reduce path loss in beyond-line-of-sight propagation, improve the coverage and reliability of the communication system, and further overcome the performance bottlenecks of traditional beyond-line-of-sight communication.

[0004] Currently, the parabolic equation method has become the mainstream numerical method for modeling radio wave propagation in evaporating waveguide environments due to its ability to accurately handle atmospheric refraction, terrain diffraction, and multipath effects. It can efficiently perform high-precision simulations of core parameters such as path loss and field strength distribution, providing reliable theoretical support for the design of beyond-line-of-sight communication systems. However, existing parabolic equation modeling methods are mainly aimed at natural evaporating waveguide environments and have not fully considered the active modulation effect of RIS on radio wave propagation. Therefore, it is difficult to accurately evaluate the performance of beyond-line-of-sight communication under RIS assistance. Summary of the Invention

[0005] The purpose of this invention is to provide a method, system, device and medium for evaluating the performance of evaporating waveguide beyond-line-of-sight communication based on RIS assistance, which can solve the problem of difficulty in accurately evaluating the performance of evaporating waveguide beyond-line-of-sight communication under RIS assistance.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a RIS-assisted method for evaluating the performance of evaporative waveguide beyond-line-of-sight communication, comprising the following steps: Meteorological parameters of the evaporation waveguide environment containing smart metasurfaces are obtained, and atmospheric refractive index profile of the evaporation waveguide environment is constructed based on the meteorological parameters. Based on the spatial location of the smart metasurface in the evaporation waveguide environment, as well as the reflection characteristics and controllable phase response of the smart metasurface, the smart metasurface is modeled as a generalized impedance boundary. The fast phase change of electromagnetic waves in the evaporation waveguide environment on the generalized impedance boundary is stripped to construct the generalized impedance boundary as an auxiliary function, and the auxiliary function is subjected to backward difference processing to obtain the discrete auxiliary function. Based on the discrete hybrid Fourier transform iterative method, the slowly varying envelope field of electromagnetic waves is solved by backward difference in the vertical direction of the evaporation waveguide environment through discrete auxiliary functions, and the atmospheric refractive index profile is used to correct the atmospheric refraction phase of the slowly varying envelope field to obtain the target slowly varying envelope field. A parabolic equation model of the evaporating waveguide environment is established based on the target slowly varying envelope field, so as to evaluate the beyond-line-of-sight communication performance of the evaporating waveguide environment through the parabolic equation model.

[0007] Furthermore, the discrete hybrid Fourier transform iterative method, by performing a backward differential solution on the slowly varying envelope field of the electromagnetic wave in the vertical direction of the evaporating waveguide environment using a discrete auxiliary function, and by correcting the atmospheric refraction phase of the slowly varying envelope field using the atmospheric refractive index profile, obtains the target slowly varying envelope field, including: The value of the discrete auxiliary function is calculated based on the slowly varying envelope field of the electromagnetic wave at its current propagation position in the evaporating waveguide environment; wherein, the slowly varying envelope field of the electromagnetic wave at its initial propagation position in the evaporating waveguide environment is determined based on the meteorological parameters of the evaporating waveguide environment. The calculated discrete auxiliary function value is subjected to a one-dimensional discrete sine transform operation to transform it to the wavenumber domain to obtain the slowly varying envelope field corresponding to the wavenumber domain. The slowly varying envelope field corresponding to the wavenumber domain is then stepped along the propagation direction of the electromagnetic wave to obtain the value of the discrete auxiliary function after one step. Based on the value of the discrete auxiliary function after one step, the slowly varying envelope field after one step is determined, and the corresponding atmospheric refraction phase correction is performed through the atmospheric refractive index profile to obtain the corrected slowly varying envelope field after one step. By iteratively applying the above steps, the modified slowly varying envelope field at all propagation positions of the electromagnetic wave in the evaporating waveguide environment is obtained, which serves as the target slowly varying envelope field.

[0008] Furthermore, the step of calculating the value of the discrete auxiliary function based on the slowly varying envelope field of the electromagnetic wave at its current propagation position in the evaporating waveguide environment includes: Depending on whether the boundary field at the current propagation position of the electromagnetic wave in the evaporating waveguide environment has a generalized impedance boundary, the slowly varying envelope field at the corresponding propagation position is substituted into the discrete auxiliary function based on the combined effect of the sea surface and the smart metasurface on the electromagnetic wave, or based on the effect of the sea surface on the electromagnetic wave, to calculate the value of the discrete auxiliary function.

[0009] Further, determining the slowly varying envelope field after one step based on the value of the discrete auxiliary function after one step includes: Based on the theory of ordinary differential equations, the particular solution and general solution of the slowly varying envelope field after one step are obtained by taking the value of the discrete auxiliary function after one step. The coefficients of the general solution are determined based on the form of the solution of the slowly varying envelope field after one step and the boundary conditions of the electromagnetic wave in the vertical direction. By combining the coefficients of the general solution with the particular solution and the general solution, the slowly varying envelope field after one step is obtained.

[0010] Furthermore, the generalized impedance boundary is: ; In the formula, Represents the slowly varying envelope field of electromagnetic waves. Indicates vertical height. Indicates the distance from the Earth's center to the field point. Represents the Earth's radius. Indicates the height of the intelligent metasurface. Impedance boundary coefficient of smart metasurfaces.

[0011] Furthermore, the construction of the atmospheric refractive index profile of the evaporation waveguide environment based on meteorological parameters includes: Based on the NAVSLaM model, an atmospheric refractive index profile of the evaporation waveguide environment is constructed according to meteorological parameters; among which, meteorological parameters include at least air temperature, wind speed, atmospheric pressure, relative humidity and sea surface temperature.

[0012] Furthermore, the beyond-line-of-sight communication performance of the evaporating waveguide environment is evaluated in the following manner: Based on the parabolic equation model of the evaporating waveguide environment, the propagation path loss of electromagnetic waves is determined to evaluate the beyond-line-of-sight communication performance of the evaporating waveguide environment.

[0013] Embodiments of the present invention also provide a RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation system, comprising: The parameter acquisition module is used to acquire meteorological parameters of the evaporation waveguide environment containing the smart metasurface, and to construct the atmospheric refractive index profile of the evaporation waveguide environment based on the meteorological parameters. The RIS modeling module is used to model the smart metasurface as a generalized impedance boundary based on the spatial location of the smart metasurface in the evaporation waveguide environment, as well as the reflection characteristics and controllable phase response of the smart metasurface. The function construction module is used to strip the fast phase of electromagnetic waves in the evaporating waveguide environment on the generalized impedance boundary, so as to construct the generalized impedance boundary as an auxiliary function, and perform backward difference processing on the auxiliary function to obtain the discrete auxiliary function. The envelope field solution module is used to solve the slowly varying envelope field of electromagnetic waves in the vertical direction of the evaporation waveguide environment by using the discrete hybrid Fourier transform iterative method and the discrete auxiliary function. It also corrects the atmospheric refraction phase of the slowly varying envelope field by using the atmospheric refractive index profile to obtain the target slowly varying envelope field. The performance evaluation module is used to establish a parabolic equation model of the evaporating waveguide environment based on the target slowly varying envelope field, so as to evaluate the beyond-line-of-sight communication performance of the evaporating waveguide environment through the parabolic equation model.

[0014] Embodiments of the present invention also provide a computer device, including: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the above-described RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method.

[0015] Embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method.

[0016] The RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method provided by this invention has at least the following beneficial effects: First, based on the spatial location of the smart metasurface in the evaporating waveguide environment and its electromagnetic properties, namely reflection characteristics and controllable phase response, the smart metasurface is modeled as a generalized impedance boundary. This accurately reproduces the physical characteristics of the smart metasurface actively performing phase modulation. This is used as the boundary condition requirement of the parabolic equation and integrated with the parabolic equation. Considering that the original solution method of the parabolic equation cannot directly handle this generalized impedance boundary with complex phase, it is constructed as an auxiliary function. Combined with the backward differential discrete hybrid Fourier transform (DMFT) iterative solution method adapted to the RIS boundary, the fast phase change of the electromagnetic wave at the generalized impedance boundary in the evaporating waveguide environment is removed, realizing the solution of the slowly changing envelope field of the electromagnetic wave in the evaporating waveguide environment. This enables the evaluation of the beyond-line-of-sight communication performance in the evaporating waveguide environment (including the smart metasurface). Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A flowchart illustrating a RIS-assisted method for evaluating the performance of evaporative waveguide beyond-line-of-sight communication provided by this invention; Figure 2 A schematic diagram of a RIS-assisted over-the-horizon radio wave propagation model structure in an evaporating waveguide provided by the present invention; Figure 3 A schematic diagram of the computational domain and mesh generation for a parabolic equation with RIS generalized impedance boundary conditions provided by the present invention. Figure 4 This invention provides a schematic diagram of the loss distribution of beyond-line-of-sight radio wave propagation path in a scenario without RIS assistance. Figure 5 This invention provides a schematic diagram of the loss distribution of beyond-line-of-sight radio wave propagation path in a scenario assisted by RIS. Figure 6 A comparative schematic diagram showing the change of radio wave propagation path loss at a fixed height of 5 meters before and after RIS assistance as a function of distance; Figure 7 This is a magnified comparative diagram showing the change in radio wave propagation path loss at a fixed height of 5 meters before and after RIS assistance, as provided by the present invention. Detailed Implementation

[0019] 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 in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. 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.

[0020] This invention establishes a parabolic equation radio wave propagation model that integrates the RIS phase modulation mechanism, thereby enabling quantitative performance evaluation of RIS-assisted over-the-horizon communication in an evaporating waveguide environment, and providing core technical support for the optimized design and deployment of marine over-the-horizon communication systems.

[0021] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] One embodiment of the present invention relates to a RIS-assisted method for evaluating the performance of evaporating waveguide beyond-line-of-sight communication. The implementation details of the RIS-assisted method for evaluating the performance of evaporating waveguide beyond-line-of-sight communication in this embodiment are described below. The following implementation details are provided for ease of understanding and are not necessary for implementing this solution.

[0023] The specific process of the RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method in this embodiment can be described as follows: Figure 1 As shown, it includes: Step 101: Obtain meteorological parameters of the evaporation waveguide environment containing the smart metasurface, and construct an atmospheric refractive index profile of the evaporation waveguide environment based on the meteorological parameters.

[0024] Specifically, based on the NAVSLaM model, an atmospheric refractive index profile of the evaporation waveguide environment is constructed according to meteorological parameters at a certain altitude above the sea surface, providing atmospheric refraction correction for subsequent solutions to the parabolic equations. The meteorological parameters include at least air temperature, wind speed, atmospheric pressure, relative humidity, and sea surface temperature.

[0025] Step 102: Based on the spatial location of the smart metasurface in the evaporation waveguide environment and the reflection characteristics and controllable phase response of the smart metasurface, the smart metasurface is modeled as a generalized impedance boundary.

[0026] Specifically, RIS is a non-good conductor surface. Introducing RIS into the parabolic equation model requires establishing impedance boundary conditions based on RIS. The RIS interface is remodeled as a generalized impedance boundary, with the following impedance boundary conditions:

[0027] ; ; In the formula, Represents the slowly varying envelope field of electromagnetic waves. Indicates vertical height. Indicates the distance from the Earth's center to the field point. Represents the Earth's radius. Indicates the height of the intelligent metasurface; For the RIS impedance boundary coefficient, The incident angle is i, where i represents the imaginary unit, and k represents the free space wavenumber of the electromagnetic wave. For RIS reflection coefficient: ; ; In the formula, Based on the basic reflectance, Here, j represents the amplitude reflection coefficient of RIS, and j denotes the imaginary unit. For intelligent metasurfaces to incident angle Controllable phase response; The complex permittivity of RIS is 1. .

[0028] Step 103: Remove the fast-changing phase of the electromagnetic wave in the evaporating waveguide environment on the generalized impedance boundary to construct an auxiliary function for the generalized impedance boundary, and perform backward differential processing on the auxiliary function to obtain a discrete auxiliary function.

[0029] Specifically, based on the RIS impedance boundary condition defined above, we intend to construct an auxiliary function. Facilitates slow-changing envelope fields Solve the backward difference in the vertical direction at RIS.

[0030] Auxiliary functions for: ; In the formula, Indicates horizontal distance; Perform backward difference discretization on the auxiliary function in the vertical direction: ; In the formula, The vertical index ranges from 1 to N, and the values ​​are integers; dz is the vertical grid step size; the boundary conditions are... .

[0031] Define RIS discrete coefficients , thus obtaining the auxiliary function Backward differential discretization scheme at RIS: .

[0032] Step 104: Based on the discrete hybrid Fourier transform iterative method, the slowly varying envelope field of the electromagnetic wave is solved by backward difference in the vertical direction of the evaporation waveguide environment through a discrete auxiliary function, and the atmospheric refractive index profile is used to correct the atmospheric refraction phase of the slowly varying envelope field to obtain the target slowly varying envelope field.

[0033] Specifically, the value of a discrete auxiliary function is calculated based on the slowly varying envelope field of the electromagnetic wave at its current propagation position in the evaporating waveguide environment. The slowly varying envelope field at the initial propagation position of the electromagnetic wave in the evaporating waveguide environment is determined based on meteorological parameters of the evaporating waveguide environment. A one-dimensional discrete sine transform is performed on the calculated value of the discrete auxiliary function to transform it to the wavenumber domain, obtaining the corresponding slowly varying envelope field in the wavenumber domain. The slowly varying envelope field in the wavenumber domain is then stepped along the propagation direction of the electromagnetic wave to obtain the value of the discrete auxiliary function after one step. Based on the value of the discrete auxiliary function after one step, the slowly varying envelope field after one step is determined, and atmospheric refraction phase correction is performed using an atmospheric refractive index profile to obtain the corrected slowly varying envelope field after one step. Through these iterative steps, the corrected slowly varying envelope fields at all propagation positions of the electromagnetic wave in the evaporating waveguide environment are obtained, serving as the target slowly varying envelope field.

[0034] In the specific implementation, the backward differential discrete mixed Fourier transform (DMFT) iterative method is used to solve for the complete slowly varying envelope field. The backward difference method constructs relationships between data points within the boundary field, and then reconstructs these relationships in the next boundary field, ultimately solving for the entire slowly varying envelope field. First, based on the environmental parameters of the evaporation waveguide, the initial propagation position is constructed. The initial field at the location This serves as the starting point for the entire backward differential DMFT iteration process. The specific iterative calculation flow within one propagation step is as follows:

[0035] (1) Calculate the discrete auxiliary function at the current position. Based on the auxiliary function The backward difference relation shown in the backward difference discretization formula at RIS, combined with the current propagation position... Slowly varying envelope field value at the location Calculate discrete auxiliary function .

[0036] Specifically, depending on whether the boundary field at the current propagation position of the electromagnetic wave in the evaporating waveguide environment possesses a generalized impedance boundary, the slowly varying envelope field at the corresponding propagation position is substituted into the discrete auxiliary function based on either the combined effect of the sea surface and the smart metasurface on the electromagnetic wave, or the effect of the sea surface on the electromagnetic wave, to calculate the value of the discrete auxiliary function. In other words, calculating the discrete auxiliary function requires determining whether the boundary field at the current position possesses a RIS impedance boundary.

[0037] If there is a RIS impedance boundary, the auxiliary function In the backward difference discretization formula at RIS, the variables Become , The expression is: ; in: ; in: ; In the formula, For composite discrete coefficients, For the RIS impedance boundary coefficient, For sea surface boundary coefficients, The sea surface reflectance is... The complex permittivity of seawater is . , where i is the incident angle, i is the imaginary unit, and k is the free space wave number of the electromagnetic wave; However, if there is no RIS impedance boundary, the variables in the formula... Become , The expression is: .

[0038] In the formula, The coefficient of variation is the sea surface dispersion factor.

[0039] (2) Calculate the discrete auxiliary function after one step. For the discrete auxiliary function... Perform a one-dimensional discrete sine transform operation to transform to the wavenumber domain. Obtain the field distribution in the wavenumber domain. For wavenumber domain field quantities Along the direction of propagation Step:

[0040] ; In the formula, This represents the current transmission distance. For free space propagation factors, Let i be the free-space wavenumber, i be the imaginary unit, and p be the wavenumber domain variable. Step size in the direction of propagation; To propagate along the direction The wavenumber domain field after stepping. An inverse discrete sine transform is performed on the stepped wavenumber domain field to return to the spatial domain. Obtain the spatial domain auxiliary function after one step. .

[0041] (3) Calculate the slowly varying envelope field value after one step.

[0042] Based on the theory of ordinary differential equations, the particular solution and general solution of the slowly varying envelope field after one step are solved according to the value of the discrete auxiliary function after one step. The coefficients of the general solution are determined according to the form of the solution of the slowly varying envelope field after one step and the boundary conditions of the electromagnetic wave in the vertical direction. The particular solution and the general solution are combined according to the coefficients of the general solution to obtain the slowly varying envelope field after one step.

[0043] 1. Calculation of particular solution. Let the particular solution be... , by auxiliary function The backward differential discretization formula at RIS is:

[0044] ; In the formula The choice depends on whether there is a RIS at the current propagation location. or ;use Auxiliary functions on the step And the formula, calculate Special solution on step .

[0045] 2. Solving for the general solution and its coefficients. Let the general solution take the form:

[0046] ; in: ; ; ; In the formula, These are the undetermined coefficients in the general solution, because they are related to the propagation distance. It is related, so it can also be written as the propagation distance. function ; The choice depends on whether there is a RIS at the current propagation location. or ; field value according to Weighted sum; These are constant coefficients derived from the boundary conditions in the vertical direction. Their function is to ensure that the combined overall field value satisfies the upper boundary constraint conditions during the superposition of general and particular solutions. The formula is ; Combining special solutions Obtain the slowly varying envelope field value after one step. This requires calculating coefficients. .

[0047] (4) Atmospheric refraction phase correction. Considering the atmospheric refraction effect in the evaporation waveguide environment, we get:

[0048] ; In the formula, This refers to the phase screen factor (i.e., the environmental propagation factor). The atmospheric corrected refractive index describes the propagation distance in an evaporating waveguide environment. ,high Atmospheric refraction effect at that location; The slowly varying envelope field value is calculated using process (3). This completes the calculation of one propagation step, thus yielding... Slowly varying envelope field on step .

[0049] Step 105: Establish a parabolic equation model of the evaporating waveguide environment based on the target slowly varying envelope field, so as to evaluate the beyond-line-of-sight communication performance of the evaporating waveguide environment through the parabolic equation model.

[0050] Specifically, through the above iterative process, the full propagation distance is calculated, and a scalar parabolic equation model based on passive RIS assistance is obtained. Finally, based on the parabolic equation model of the evaporating waveguide environment, the propagation path loss of electromagnetic waves is determined, so as to realize the performance evaluation of beyond-line-of-sight communication under RIS assistance.

[0051] The RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method of the present invention has the following beneficial effects: 1. Achieving integrated modeling of RIS and parabolic equations: By constructing generalized impedance boundary conditions for RIS, the active phase modulation effect of RIS is accurately integrated into the parabolic equation, solving the technical problem that existing methods cannot quantify the influence of RIS on the propagation of radio waves in evaporating waveguides, and providing a complete theoretical modeling scheme for RIS-assisted beyond-line-of-sight communication. 2. Significantly improves beyond-line-of-sight communication performance: By utilizing RIS to actively control the propagation path of electromagnetic waves, electromagnetic waves that would otherwise diverge or attenuate are refocused, reflected, or refracted to a specified direction, reducing communication blind spots. Combined with high-precision simulation of the propagation characteristics of evaporating waveguides using parabolic equations, the signal binding and transmission within the waveguide layer are effectively enhanced, reducing energy divergence, lowering path loss, and improving communication reliability, thus breaking through the performance bottleneck of traditional beyond-line-of-sight communication. 3. Balancing simulation accuracy and computational efficiency: An innovative backward differential DMFT iterative solution method adapted to RIS boundaries is proposed. While ensuring the simulation accuracy of radio wave propagation in the evaporating waveguide environment, it achieves efficient solution of the slowly varying envelope field and can quickly output core performance parameters such as path loss, meeting the needs of engineering simulation. 4. Wide adaptability to various scenarios: The method can be flexibly adapted to different RIS parameters and different evaporation waveguide environments, and is suitable for multiple scenarios such as marine communication, radar detection, and emergency communication, with extremely high practical value and prospects for promotion.

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and specific examples. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0053] This embodiment implements a RIS-assisted performance evaluation calculation for beyond-line-of-sight communication within an evaporating waveguide based on the MATLAB platform, and the process strictly follows... Figure 1 The method shown simulates a typical marine evaporative waveguide environment. The communication frequency is set to 10 GHz, the transmitting antenna height is 5 m, horizontal polarization is used, the propagation distance is 0–120 km, and the height is 0–30 m. Atmospheric scattering and sea surface wind field effects are not considered in the computational domain, and the complex permittivity ε of seawater is 81 - j25. The effectiveness and accuracy of the proposed method are verified by comparing scenarios with and without a RIS (Radiated Reflector System). The RIS parameters are: length 5 m, width 5 m, installation height 10 m, and deployment distance at 90 km. It can perform phase modulation and low-loss reflection of incident electromagnetic waves, such as... Figure 2 As shown.

[0054] Step 1: Using meteorological parameters such as air temperature, wind speed, atmospheric pressure, relative humidity, and sea surface temperature at a certain altitude above the sea surface, calculate the atmospheric corrected refractive index profile based on the NAVSLaM model to obtain the evaporation waveguide height, providing an atmospheric refraction correction basis for subsequent parabolic equation solving. This embodiment sets typical marine meteorological parameters: sea surface temperature 27 ℃; air temperature 25 ℃; relative humidity 85%; wind speed 5 m / s; atmospheric pressure 1013 hPa. The NAVSLaM model calculates the evaporation waveguide height to be 15 m. The atmospheric corrected refractive index profile decreases exponentially with altitude, forming a strong electromagnetic wave trapping layer within the 0-15 m altitude range. This allows electromagnetic waves to propagate beyond the line-of-sight within the waveguide layer, providing a standard propagation environment for subsequent RIS-assisted control.

[0055] Step 2: To introduce the RIS modulation effect, establish the RIS generalized impedance boundary condition: ; in: ; ; ; In the formula, The slowly varying envelope field of the electromagnetic wave is the variable to be solved. The radius of the Earth is taken as 6371 km; The height of the RIS is set to 10 m. Let be the angle of incidence of the electromagnetic wave, taken as 3°; Let be the complex permittivity of RIS, taken as 3.0 - j0.02; The RIS amplitude reflection coefficient is set to 0.95. For the RIS controllable phase response, take 3.136 rad; The free-space wavenumber is 209.44 rad / m; i and j are imaginary units.

[0056] The basic reflection coefficient was calculated. =0.85 - j0.12; RIS reflection coefficient =-0.81 +j0.11; RIS impedance boundary factor It is 12.56 + j152.3.

[0057] Step 3: Construct an auxiliary function based on the RIS impedance boundary condition: ; Perform vertical backward difference discretization on the auxiliary function: ; In the formula, the vertical grid step size dz is taken as 0.05 m. Substitute dz into the equation and define the RIS discrete coefficients. Calculations yielded Given 0.992 - j0.0076, the simplified discrete scheme is obtained:

[0058] ; Step 4: Discretize the entire boundary field, and select different simplified discretization schemes depending on whether the boundary field at the current position has a RIS impedance boundary.

[0059] If the current location has a RIS impedance boundary, then considering the combined effect of the sea surface and RIS, the composite simplified discretization scheme is as follows: ; In the formula, For composite discrete coefficients, Let be the sea surface boundary coefficient, taken as 80.5 + j120.3, and substitute it into... The composite discrete coefficients can be obtained from dz. If the sum is 0.985 - j0.0091, then the composite simplified discrete scheme becomes: ; If there is no RIS impedance boundary at the current location, then only the effect of the sea surface is considered, and the simplified discretization scheme of the sea surface is as follows: ; In the formula, Let be the sea surface dispersion coefficient, and substitute it into... and The sea surface dispersion coefficient can be obtained If the value is 0.988 - j0.0085, then the simplified discrete scheme of the sea surface becomes: ; Combining steps 2, 3, and 4, the boundary coupling between the RIS and the parabolic equation model is completed, resulting in the discretized boundary field, corresponding to... Figure 3 The computational region and grid division are shown.

[0060] Step 5: Solve for the slowly varying envelope field of the radio wave for the entire discretized boundary field. : (1) Determine the initial propagation position based on the meteorological parameters of the evaporation waveguide environment. Slowly changing envelope field ; (2) Determine whether the current propagation position has a RIS impedance boundary. If it has a RIS impedance boundary, the discrete auxiliary function is obtained as follows:

[0061] ; Without the RIS impedance boundary, the discrete auxiliary function is obtained as follows: ; (3) Perform a one-dimensional discrete sine transform operation on the discrete auxiliary function obtained in (2) to transform it to the wavenumber domain p, and obtain the field distribution corresponding to the wavenumber domain. ; (4) Regarding (3) Multiplied by free space propagation factor Obtain the wavenumber field after one step .in, The free-space wavenumber is taken as 209.44 rad / m; The propagation direction step size is set to 10 m; p is a wavenumber domain variable, ranging from 0 to 628 rad / m.

[0062] (5) Perform an inverse discrete sine transform on U(10,jdp) in (4) and return to the spatial domain z to obtain the spatial domain auxiliary function w(10,0.05n) after one step. (6) Determine whether the position after one step has a RIS impedance boundary. If it has a RIS impedance boundary, the relationship between the particular solution of the slowly varying envelope field after one step and the discrete auxiliary function after one step is:

[0063] ; Without the RIS impedance boundary, the relationship between the particular solution of the slowly varying envelope field after one step and the discrete auxiliary function after one step is as follows: ; Substitute w(10,0.05n) obtained in (5) and determine whether there is a RIS impedance boundary at this position after one step, and obtain the particular solution after one step. .

[0064] (7) The vertical grid number N is 600. If the position after one step has a RIS impedance boundary, r is taken as 0.985 - j0.0091, and D is taken as... If there is no RIS impedance boundary at the position after one step, then r is taken as... D According to the particular solution obtained in (6) Calculate separately , , Thus, the general solution after one step is obtained. .

[0065] (8) Regarding (7) Multiply by the phase screen factor ,in, For the distance of transmission ,high Atmospheric corrected refractive index at this location, where the value is taken as... The corrected slowly varying envelope field after one step is obtained. .

[0066] (9) Repeat steps (1) to (8) for iterative calculation to obtain the slow-varying envelope field of the entire propagation area.

[0067] Step 6: Calculate the radio wave propagation path loss based on the slowly varying envelope field distribution of the entire propagation area. ; In the formula, f is the carrier frequency, with a value of 10 GHz; d is the propagation slant range, ranging from 0 m to 120000 m; and u is the amplitude of the slowly varying envelope field obtained by solving.

[0068] Step 7: Calculate the radio wave propagation path loss for the two scenarios with and without RIS assistance based on Step 6. The results are as follows: Figure 4 and Figure 5 As shown. Figure 5The RIS (Radio Router Array) is placed at a propagation distance of 90,000 meters and a height of 10 meters. The receiver is fixed at a propagation distance of 90,170 meters and a height of 5 meters. Plot the path loss at the receiver's height as a function of distance, with and without the RIS, for example. Figure 6 As shown, it can be seen that the path loss of radio waves after the RIS position is improved with RIS assistance. A local magnification of the path loss versus distance graph for the receiver's location yields... Figure 7 It can be seen that at the receiver's location of 90170 meters and a height of 5 meters: the path loss for beyond-line-of-sight radio wave propagation without RIS assistance is 135.5 dB; while the path loss for beyond-line-of-sight radio wave propagation with RIS assistance is 128.4 dB, a reduction of 7.1 dB, showing significant improvement. The results indicate that the method proposed in this invention effectively reduces the path loss for beyond-line-of-sight propagation in the evaporating waveguide environment after the RIS location by controlling the electromagnetic wave propagation path through RIS, thereby improving far-field communication performance and coverage.

[0069] The steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split into multiple steps. As long as they include the same logical relationship, they are all within the protection scope of this invention. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, without changing the core design of the algorithm and process, are also within the protection scope of this invention.

[0070] Another embodiment of the present invention relates to a RIS-assisted evaporating waveguide beyond-line-of-sight communication performance evaluation system. The implementation details of this RIS-assisted evaporating waveguide beyond-line-of-sight communication performance evaluation system are described below. The following implementation details are provided for ease of understanding and are not essential for implementing this solution. This RIS-assisted evaporating waveguide beyond-line-of-sight communication performance evaluation system includes: The parameter acquisition module is used to acquire meteorological parameters of the evaporation waveguide environment containing the smart metasurface, and to construct the atmospheric refractive index profile of the evaporation waveguide environment based on the meteorological parameters. The RIS modeling module is used to model the smart metasurface as a generalized impedance boundary based on the spatial location of the smart metasurface in the evaporation waveguide environment, as well as the reflection characteristics and controllable phase response of the smart metasurface. The function construction module is used to strip the fast phase of electromagnetic waves in the evaporating waveguide environment on the generalized impedance boundary, so as to construct the generalized impedance boundary as an auxiliary function, and perform backward difference processing on the auxiliary function to obtain the discrete auxiliary function. The envelope field solution module is used to solve the slowly varying envelope field of electromagnetic waves in the vertical direction of the evaporation waveguide environment by using the discrete hybrid Fourier transform iterative method and the discrete auxiliary function. It also corrects the atmospheric refraction phase of the slowly varying envelope field by using the atmospheric refractive index profile to obtain the target slowly varying envelope field. The performance evaluation module is used to establish a parabolic equation model of the evaporating waveguide environment based on the target slowly varying envelope field, so as to evaluate the beyond-line-of-sight communication performance of the evaporating waveguide environment through the parabolic equation model.

[0071] It is not difficult to see that this embodiment is a system embodiment corresponding to the above method embodiments, and this embodiment can be implemented in conjunction with the above method embodiments. The relevant technical details and technical effects mentioned in the above embodiments are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the above embodiments.

[0072] It is worth mentioning that all modules involved in this embodiment are logical modules. In practical applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. Furthermore, to highlight the innovative aspects of this invention, this embodiment does not introduce units that are not closely related to solving the technical problem proposed by this invention; however, this does not mean that other units are absent from this embodiment.

[0073] Another embodiment of the present invention relates to a computer device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method in the above embodiments.

[0074] The memory and processor are connected via a bus, which can include any number of interconnecting buses and bridges, connecting various circuits of one or more processors and memories. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0075] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0076] Another embodiment of the present invention relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the method embodiments described above.

[0077] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor 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.

[0078] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A RIS-assisted method for evaluating the performance of evaporative waveguide beyond-line-of-sight communication, characterized in that, The method includes: Meteorological parameters of the evaporation waveguide environment containing smart metasurfaces are obtained, and atmospheric refractive index profile of the evaporation waveguide environment is constructed based on the meteorological parameters. Based on the spatial location of the smart metasurface in the evaporation waveguide environment, as well as the reflection characteristics and controllable phase response of the smart metasurface, the smart metasurface is modeled as a generalized impedance boundary. The fast phase change of electromagnetic waves in the evaporation waveguide environment on the generalized impedance boundary is stripped to construct the generalized impedance boundary as an auxiliary function, and the auxiliary function is subjected to backward difference processing to obtain the discrete auxiliary function. Based on the discrete hybrid Fourier transform iterative method, the slowly varying envelope field of electromagnetic waves is solved by backward difference in the vertical direction of the evaporation waveguide environment through discrete auxiliary functions, and the atmospheric refractive index profile is used to correct the atmospheric refraction phase of the slowly varying envelope field to obtain the target slowly varying envelope field. A parabolic equation model of the evaporating waveguide environment is established based on the target slowly varying envelope field, so as to evaluate the beyond-line-of-sight communication performance of the evaporating waveguide environment through the parabolic equation model.

2. The RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method according to claim 1, characterized in that, The discrete hybrid Fourier transform iterative method, through a discrete auxiliary function, performs a backward differential solution for the slowly varying envelope field of the electromagnetic wave in the vertical direction of the evaporating waveguide environment, and corrects the atmospheric refraction phase of the slowly varying envelope field using the atmospheric refractive index profile, to obtain the target slowly varying envelope field, including: The value of the discrete auxiliary function is calculated based on the slowly varying envelope field of the electromagnetic wave at its current propagation position in the evaporating waveguide environment; wherein, the slowly varying envelope field of the electromagnetic wave at its initial propagation position in the evaporating waveguide environment is determined based on the meteorological parameters of the evaporating waveguide environment. The calculated discrete auxiliary function value is subjected to a one-dimensional discrete sine transform operation to transform it to the wavenumber domain to obtain the slowly varying envelope field corresponding to the wavenumber domain. The slowly varying envelope field corresponding to the wavenumber domain is then stepped along the propagation direction of the electromagnetic wave to obtain the value of the discrete auxiliary function after one step. Based on the value of the discrete auxiliary function after one step, the slowly varying envelope field after one step is determined, and the corresponding atmospheric refraction phase correction is performed through the atmospheric refractive index profile to obtain the corrected slowly varying envelope field after one step. By iteratively applying the above steps, the modified slowly varying envelope field at all propagation positions of the electromagnetic wave in the evaporating waveguide environment is obtained, which serves as the target slowly varying envelope field.

3. The RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method according to claim 2, characterized in that, The calculation of the discrete auxiliary function based on the slowly varying envelope field of the electromagnetic wave at its current propagation position in the evaporating waveguide environment includes: Depending on whether the boundary field at the current propagation position of the electromagnetic wave in the evaporating waveguide environment has a generalized impedance boundary, the slowly varying envelope field at the corresponding propagation position is substituted into the discrete auxiliary function based on the combined effect of the sea surface and the smart metasurface on the electromagnetic wave, or based on the effect of the sea surface on the electromagnetic wave, to calculate the value of the discrete auxiliary function.

4. The RIS-assisted performance evaluation method for evaporative waveguide beyond-line-of-sight communication according to claim 3, characterized in that, Determining the slowly varying envelope field after one step based on the value of the discrete auxiliary function after one step includes: Based on the theory of ordinary differential equations, the particular solution and general solution of the slowly varying envelope field after one step are obtained by taking the value of the discrete auxiliary function after one step. The coefficients of the general solution are determined based on the form of the solution of the slowly varying envelope field after one step and the boundary conditions of the electromagnetic wave in the vertical direction. By combining the coefficients of the general solution with the particular solution and the general solution, the slowly varying envelope field after one step is obtained.

5. The RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation method according to claim 1, characterized in that, The generalized impedance boundary is: ； In the formula, Represents the slowly varying envelope field of electromagnetic waves. Indicates vertical height. Indicates the distance from the Earth's center to the field point. Represents the Earth's radius. Indicates the height of the intelligent metasurface. is the impedance boundary coefficient of the smart metasurface.

6. The RIS-assisted performance evaluation method for evaporative waveguide beyond-line-of-sight communication according to claim 1, characterized in that, The atmospheric refractive index profile of the evaporation waveguide environment constructed based on meteorological parameters includes: Based on the NAVSLaM model, an atmospheric refractive index profile of the evaporation waveguide environment is constructed according to meteorological parameters; among which, meteorological parameters include at least air temperature, wind speed, atmospheric pressure, relative humidity and sea surface temperature.

7. The RIS-assisted performance evaluation method for evaporative waveguide beyond-line-of-sight communication according to claim 1, characterized in that, The beyond-line-of-sight communication performance of the evaporating waveguide environment was evaluated in the following ways: Based on the parabolic equation model of the evaporating waveguide environment, the propagation path loss of electromagnetic waves is determined to evaluate the beyond-line-of-sight communication performance of the evaporating waveguide environment.

8. A RIS-assisted evaporation waveguide beyond-line-of-sight communication performance evaluation system, characterized in that, The system includes: The parameter acquisition module is used to acquire meteorological parameters of the evaporation waveguide environment containing the smart metasurface, and to construct the atmospheric refractive index profile of the evaporation waveguide environment based on the meteorological parameters. The RIS modeling module is used to model the smart metasurface as a generalized impedance boundary based on the spatial location of the smart metasurface in the evaporation waveguide environment, as well as the reflection characteristics and controllable phase response of the smart metasurface. The function construction module is used to strip the fast phase of electromagnetic waves in the evaporating waveguide environment on the generalized impedance boundary, so as to construct the generalized impedance boundary as an auxiliary function, and perform backward difference processing on the auxiliary function to obtain the discrete auxiliary function. The envelope field solution module is used to solve the slowly varying envelope field of electromagnetic waves in the vertical direction of the evaporation waveguide environment by using the discrete hybrid Fourier transform iterative method and the discrete auxiliary function. It also corrects the atmospheric refraction phase of the slowly varying envelope field by using the atmospheric refractive index profile to obtain the target slowly varying envelope field. The performance evaluation module is used to establish a parabolic equation model of the evaporating waveguide environment based on the target slowly varying envelope field, so as to evaluate the beyond-line-of-sight communication performance of the evaporating waveguide environment through the parabolic equation model.

9. A computer device, characterized in that, include: At least one processor; And a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the RIS-assisted evaporative waveguide beyond-line-of-sight communication performance evaluation method as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the RIS-assisted performance evaluation method for evaporative waveguide beyond-line-of-sight communication as described in any one of claims 1 to 7.

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