Evaporative waveguide over-the-horizon emergency communication modeling method and system based on ray tracing

Abstract

The present invention belongs to the field of wireless communication network technology and provides a ray tracing-based modeling and system for over-the-horizon emergency communication in an evaporation duct. The method includes calculating the vertical distribution of atmospheric thermodynamic temperature, atmospheric pressure, and water vapor pressure, thereby inverting the evaporation duct parameters and obtaining the vertical distribution of the refractive index; tracing ray trajectories based on the vertical distribution of the refractive index; comparing the height of each ray at a horizontal distance from the receiving antenna with the height of the receiving antenna to obtain possible eigenrays that meet preset conditions; determining whether the possible eigenrays are eigenrays, and screening all eigenrays to find several eigenrays with significantly different paths as the central rays of a ray tube with an opening angle of #imgabs0#; calculating the maximum height difference of all rays in the ray tube at a horizontal distance from the receiving antenna to obtain the vertical cross-sectional width of the ray tube, and using this to calculate the propagation factor and path loss of each eigenray.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication networks, and in particular relates to an evaporation waveguide over-the-horizon emergency communication modeling and system based on ray tracing. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] To capitalize on more stable wind energy resources, wind farms have been relocated offshore, first to shallower waters near shore and now extending to deeper waters and further from shore. Deepwater, offshore solutions will enable access to large areas with strong winds and reduced sensitivity to noise, visual impact, and size. However, the deep water depths and harsh offshore environment, with rapid fluctuations in ambient temperature, air pressure, and humidity, increase the operational risks of offshore wind turbines and lead to higher failure rates. Furthermore, offshore wind farms are extremely difficult to access, making the cost of developing and operating offshore wind farms several times that of onshore wind farms. Once an offshore wind turbine is damaged or experiences a performance malfunction, resulting in equipment downtime or grid connection failure, repairs must be performed by yachts, crane vessels, or even helicopters. This is difficult, time-consuming, and costly, posing significant threats to the socioeconomic situation, facility safety, vessel safety, and the personal safety of personnel.

[0004] In the face of such incidents, secure and reliable wireless communication technology is particularly important. The rapid development of new power generation technologies based on renewable energy has led to significant development and changes in modern power systems. Communication technology plays an increasingly important role in ensuring the stability, reliability, and security of power systems. Emergency communications are the cornerstone of smooth power grid emergency response and relief efforts. In the event of sudden disasters and accidents, a communication link must be quickly established between the emergency command center and the emergency site to ensure emergency command and rapid repairs. Offshore wind farms are located far from land, making the establishment of communication infrastructure extremely difficult. Furthermore, due to the long communication distances, communication quality cannot be guaranteed.

[0005] As a key component of the radio wave environment, atmospheric ducts are specialized super-refractive atmospheric layered structures formed within the troposphere, particularly within the atmospheric boundary layer, that enable long-distance, beyond-line-of-sight (bLoS) propagation of electromagnetic waves. These structures can be utilized to enable applications such as beyond-line-of-sight detection and communication in the ultrashortwave and microwave bands. They represent a high-quality channel resource that can significantly enhance the communication assurance capabilities of bLoS links. Atmospheric ducts primarily include evaporation ducts, surface ducts, and suspended ducts. Evaporation ducts are formed by large water vapor gradients near the surface layer caused by evaporation from large bodies of water. Due to high evaporation rates, evaporation ducts are virtually permanent in coastal and marine environments. For example, evaporation ducts dominate 90% of the time in equatorial and tropical regions. Experimental studies have also shown that in the lower troposphere, particularly between 2 and 20 GHz, duct-layer communication becomes the primary propagation mechanism.

[0006] Ray tracing (RT) technology in tropospheric propagation is based on the principles of geometric optics (GO). It simulates the propagation paths of rays (light) to determine reflections, refractions, and shadows. In the atmosphere, it can track not only the propagation trajectories of radio waves under normal atmospheric conditions, but also the anomalous propagation trajectories of radio waves in atmospheric waveguides. For radio wave propagation, high frequencies allow the use of geometric optics approximations, where the wave field energy appears to be transmitted along certain curved paths called rays. These rays contain a wealth of important information, recreating the physical scenario of radio wave propagation and intuitively illustrating the propagation trajectories required in applications such as radar, as well as spatial position and angle of arrival in positioning problems. RT utilizes solutions to the Eikonel equation under nonstandard refractive index conditions to approximate the delay spread and direction of arrival behavior of multipath components.

[0007] In offshore wind farm emergency communications scenarios, existing emergency response methods have certain shortcomings. Satellite communications have high operation and maintenance costs, high signal transmission latency, and poor video backhaul quality, posing security risks. High-data-rate cellular communications infrastructure is difficult to build, communication quality cannot be guaranteed, and is easily affected by meteorological factors. Without relay equipment, microwave frequency band communications can only achieve line-of-sight communication. Wired communications or the use of relay nodes are unstable, pose significant security risks, and have high maintenance costs. Summary of the Invention

[0008] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides an evaporation waveguide over-the-horizon emergency communication modeling and system based on ray tracing, which can simultaneously estimate the large-scale parameters and small-scale parameters of the channel when using the ray tracing method to track the abnormal propagation trajectory of radio waves in the atmospheric waveguide, providing a good reference for the implementation of channel modeling.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A first aspect of the present invention provides a ray tracing-based modeling of over-the-horizon emergency communications in an evaporative waveguide.

[0011] Ray tracing-based modeling of over-the-horizon emergency communications using evaporative waveguides, including:

[0012] Based on the set environmental parameters, the evaporation duct diagnostic model is used, combined with basic meteorological elements at a certain height, to calculate the vertical distribution of atmospheric thermodynamic temperature, atmospheric pressure, and water vapor pressure. This is used to invert the evaporation duct parameters and obtain the vertical distribution of refractive index.

[0013] The ray trajectory is traced based on the vertical distribution of the refractive index. After the ray departs from the transmitting antenna at a certain departure angle, Snell's law is used to calculate the changing angles of incidence and refraction or reflection. The propagation of light in the layered atmosphere is simulated by combining wavelength, altitude, distance, and delay data until the light reaches the preset propagation distance or maximum limit altitude, resulting in a complete ray trajectory.

[0014] Compare the height of each ray at the horizontal distance of the receiving antenna with the height of the receiving antenna to obtain possible eigenrays that meet the preset conditions;

[0015] For a departure angle of The possible eigenrays of If the heights of the two rays at the horizontal distance from the receiving antenna include the height of the receiving antenna, then the possible eigenray is an eigenray; wherein the eigenray is a ray that reaches the receiver from the transmitter through a certain path;

[0016] Screen all eigenrays and find several eigenrays with significantly different paths;

[0017] Each eigenray after screening is taken as the departure angle. The central ray of the ray tube is used to calculate the maximum height difference of all rays in the ray tube at the horizontal distance of the receiving antenna, and the vertical cross-sectional width of the ray tube is obtained. Based on this, the propagation factor, path loss, delay spread and arrival angle of each intrinsic ray are calculated, and the solid line communication model is constructed.

[0018] A second aspect of the present invention provides a modeling system for evaporation waveguide beyond-the-horizon communication based on ray tracing.

[0019] The modeling system of evaporation waveguide beyond-horizon communication based on ray tracing includes:

[0020] The refractive index calculation module is configured to: calculate the vertical distribution of atmospheric thermodynamic temperature, atmospheric pressure, and water vapor pressure based on the set environmental parameters using the evaporation duct diagnostic model and combining basic meteorological elements at a certain altitude, thereby inverting the evaporation duct parameters to obtain the vertical distribution of the refractive index;

[0021] A ray trajectory construction module is configured to: trace ray trajectories based on the vertical distribution of refractive index. After the ray departs from the transmitting antenna at a certain departure angle, Snell's law is used to calculate the changing angles of incidence and refraction or reflection. The propagation of light in a stratified atmosphere is simulated by combining wavelength, altitude, distance, and delay data until the ray reaches a preset propagation distance or a maximum altitude, resulting in a complete ray trajectory.

[0022] a possible eigenray determination module, configured to: compare the height of each ray at a horizontal distance from the receiving antenna with the height of the receiving antenna to obtain possible eigenrays that meet preset conditions;

[0023] The eigenray determination module is configured to: for a ray with a departure angle of The possible eigenrays of If the heights of the two rays at the horizontal distance from the receiving antenna include the height of the receiving antenna, then the possible eigenray is an eigenray; wherein the eigenray is a ray that reaches the receiver from the transmitter through a certain path;

[0024] A screening module is configured to: screen all eigenrays to find a number of eigenrays with significantly different paths;

[0025] The modeling module is configured as follows: each eigenray after screening is used as a departure angle with an angle of The central ray of the ray tube is used to calculate the maximum height difference of all rays in the ray tube at the horizontal distance of the receiving antenna, and the vertical cross-sectional width of the ray tube is obtained. Based on this, the propagation factor, path loss, delay spread and arrival angle of each intrinsic ray are calculated, and the solid line communication model is constructed.

[0026] A third aspect of the present invention provides a computer-readable storage medium.

[0027] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps in the ray tracing-based over-the-horizon emergency communication modeling of an evaporation waveguide as described in the first aspect above.

[0028] A fourth aspect of the present invention provides a computer device.

[0029] A computer device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the ray tracing-based over-the-horizon emergency communication modeling for evaporation waveguides as described in the first aspect above are implemented.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] In this invention, we have developed an evaporation waveguide refractive index distribution prediction and ray tracing program for bLoS communication based on MATLAB to solve the propagation problem of bLoS in the marine evaporation waveguide environment. The vertical distribution of the refractive index is predicted and corrected according to the environmental parameters, the propagation process of light is simulated, and channel parameters such as path loss, delay spread and wave arrival direction are estimated. Applying the RT-based algorithm to the marine evaporation waveguide environment can well achieve the estimation of large-scale parameters and small-scale parameters at the same time, making up for the shortcomings of other modeling methods such as the parabolic equation (PE). It provides an optional modeling scheme for realizing bLoS communication using the waveguide layer in emergency scenarios of offshore wind farms. This beyond-line-of-sight communication directly utilizes the environmental characteristics of the sea, and the infrastructure construction is relatively simple, which has great reference significance for subsequent practical use. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1 This is a schematic diagram of the application of the over-the-horizon communication modeling in the evaporation waveguide environment of the present invention to the emergency communication scenario of an offshore wind farm;

[0034] Figure 2 A vertical profile of the corrected refractive index in the evaporation waveguide environment of the present invention;

[0035] Figure 3 This is a diagram showing the ray trajectory tracing results in the evaporation waveguide environment of the present invention;

[0036] Figure 4 A graph showing the relationship between path loss estimated by the ray tracing method of the present invention and distance;

[0037] Figure 5 A graph showing the relationship between time delay estimated by the ray tracing method of the present invention and distance;

[0038] Figure 6 A distribution diagram of arrival angles estimated by the ray tracing method of the present invention;

[0039] Figure 7Flowchart of the ray trajectory tracing algorithm in the present invention;

[0040] Figure 8 Flowchart for modeling the evaporation waveguide over-the-horizon emergency communication based on ray tracing in the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the methods and systems according to the various embodiments of the present disclosure. It should be noted that each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the module, program segment, or a part of code can include one or more executable instructions for implementing the logical functions specified in the various embodiments. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the flowchart and / or block diagram, and the combination of the boxes in the flowchart and / or block diagram, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or can be implemented using a combination of dedicated hardware and computer instructions.

[0045] Explanation of terms:

[0046] bLoS means beyond line of sight;

[0047] UAV refers to unmanned aerial vehicles;

[0048] RT refers to ray tracing;

[0049] GO refers to geometrical optics.

[0050] Example 1

[0051] like Figure 8 As shown, this embodiment provides an evaporation waveguide over-the-horizon emergency communication modeling based on ray tracing. This embodiment uses the method applied to the server as an example for illustration. It can be understood that the method can also be applied to terminals, and can also be applied to a system including terminals, servers, and servers, and implemented through the interaction between terminals and servers. The server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network servers, cloud communications, middleware services, domain name services, security services CDN, and big data and artificial intelligence platforms. The terminal can be a smart phone, tablet computer, laptop computer, desktop computer, etc., but is not limited to this. The terminal and the server can be directly or indirectly connected by wired or wireless communication, which is not limited in this application. In this embodiment, the method includes the following steps:

[0052] Based on the set environmental parameters, the evaporation duct diagnostic model is used, combined with basic meteorological elements at a certain height, to calculate the vertical distribution of atmospheric thermodynamic temperature, atmospheric pressure, and water vapor pressure. This is used to invert the evaporation duct parameters and obtain the vertical distribution of refractive index.

[0053] The ray trajectory is traced based on the vertical distribution of the refractive index. After the ray departs from the transmitting antenna at a certain departure angle, Snell's law is used to calculate the changing angles of incidence and refraction or reflection. The propagation of light in the layered atmosphere is simulated by combining wavelength, altitude, distance, and delay data until the light reaches the preset propagation distance or maximum limit altitude, resulting in a complete ray trajectory.

[0054] Compare the height of each ray at the horizontal distance of the receiving antenna with the height of the receiving antenna to obtain possible eigenrays that meet the preset conditions;

[0055] For a departure angle of The possible eigenrays of If the heights of the two rays at the horizontal distance from the receiving antenna include the height of the receiving antenna, then the possible eigenray is an eigenray; wherein the eigenray is a ray that reaches the receiver from the transmitter through a certain path;

[0056] Screen all eigenrays and find several eigenrays with significantly different paths;

[0057] Each eigenray after screening is taken as the departure angle. The central ray of the ray tube is used to calculate the maximum height difference of all rays in the ray tube at the horizontal distance of the receiving antenna, and the vertical cross-sectional width of the ray tube is obtained. Based on this, the propagation factor, path loss, delay spread and arrival angle of each intrinsic ray are calculated, and the solid line communication model is constructed.

[0058] This embodiment considers Figure 1 The offshore beyond-line-of-sight communication scenario shown in the figure. When an offshore wind turbine is damaged or experiences a performance malfunction, requiring rescue or repair operations, a bLoS communication link with both the transmitter and receiver located within the duct layer is constructed using an evaporative duct layer to provide emergency communication services. This meets the communication needs of the operation and maintenance center with maintenance personnel, ships, helicopters, and other equipment, ensuring the safety of life and property. The system initially sets environmental parameters, then inverts the evaporative duct parameters to obtain a modified vertical refractive index profile, thereby tracing ray trajectories: a ray starts at a certain departure angle at the transmitter (Tx), calculates the changing angles of incidence and refraction or reflection, and uses the calculated step size, altitude, distance, and delay to simulate the propagation of light in a stratified atmosphere until the ray reaches the preset propagation distance or maximum altitude, recording delay and angle information along the way. Several eigenrays are then searched between the transmitter and receiver to determine whether they can be received within the specified parameter range. The propagation factor for each path is calculated, and finally, the path loss is estimated. The recorded data is used to estimate channel parameters such as delay spread and angle of arrival.

[0059] The specific solution of this embodiment can be implemented by using the following contents:

[0060] Step 1: Initialize the environmental parameters including the initial departure angle range AoDrange, maximum propagation height MPH, maximum propagation distance MPD, transmitting antenna height Ht, carrier frequency F, optional parameters of the evaporation waveguide diagnostic model: atmospheric temperature AT, sea surface temperature SST, wind speed WS, water vapor pressure VP, and the initial departure angle of the narrow ray tube. Tracking step length Δs;

[0061] Step 2: Based on the set environmental parameters, the evaporation duct diagnostic model is used to calculate the vertical distribution of atmospheric thermodynamic temperature T, atmospheric pressure P, and water vapor pressure e using basic meteorological elements at a certain height (such as air temperature, air pressure, wind speed, relative humidity, etc.);

[0062] Commonly used evaporation duct diagnostic models include the BYC (Babin-Young-Carton) model, the NPS (Naval Postgraduate School) model, the PJ (Paulus-Jeske) model, the MGB (Musson-Gauthier-Bruth) model, and the pseudo-refractive index model. In the NPS model, the atmospheric thermodynamic temperature T and atmospheric pressure P are obtained by integrating the MOS (Monin-Obukhov Similarity) theory of the near-surface layer step by step according to altitude. The water vapor pressure e is calculated as follows:

[0063]

[0064]

[0065] Among them, R h is the relative humidity of the atmosphere, and exp(α) is the saturated water vapor pressure.

[0066] Step 3: Further invert the evaporation waveguide parameters based on the cross-sectional calculation results of T, P, and e to obtain the distribution of the refractive index in the vertical direction and draw the corrected refractive index cross-sectional diagram, as shown in the figure. Figure 2 As shown;

[0067] The refractive index N is defined as follows:

[0068]

[0069] Where n is the atmospheric refractive index, usually between 1.00025-1.0004.

[0070] The definitions of the atmospheric corrected refractive index m and the corrected atmospheric refractive index M are as follows:

[0071]

[0072]

[0073] Where h is the height from the Earth, r e is the average radius of the Earth.

[0074] Then the refractive index gradient and the corrected refractive index gradient can be obtained as follows:

[0075]

[0076]

[0077] Step 4: Tracing the ray trajectory from the refractive index distribution: After the ray starts at a certain departure angle at the transmitting antenna (Tx), Snell's law is used to calculate the changing angles of incidence and refraction or reflection. The calculated step size, height, distance, delay and other data are used to simulate the propagation of light in the layered atmosphere until the light reaches the preset propagation distance or maximum limit height, and a complete ray trajectory is obtained, such as Figure 3 As shown;

[0078] Certain parameter conditions are required to form atmospheric duct propagation.

[0079] The existence of atmospheric ducts in the atmospheric environment does not guarantee that electromagnetic waves can be trapped by the duct layer and form atmospheric duct propagation. Specific meteorological conditions only guarantee the occurrence of atmospheric ducts, and there are other limiting conditions for the occurrence of atmospheric duct propagation: (1) The wavelength of the electromagnetic wave must be less than the maximum trapped wavelength (the corresponding frequency must be greater than the trapped frequency), also known as the cutoff wavelength; (2) The emission elevation angle of the transmitting source must be less than the trapping angle; (3) The relative position of the atmospheric duct and the transmitting source meets certain conditions. The cutoff wavelength is the maximum wavelength of the radio wave trapped by the atmospheric duct layer under specific parameter conditions. According to the modal theory of tropospheric refraction, when electromagnetic waves form atmospheric duct propagation, the relationship between the electromagnetic wave wavelength, the atmospheric refractive index gradient and the duct thickness must meet a certain relationship. The following is an expression for the maximum wavelength that can be captured (trapped wavelength):

[0080]

[0081] and satisfy λ V =3λ H Among them, H and V represent horizontal polarization and vertical polarization respectively, n t is the atmospheric refractive index at the antenna location, h t is the antenna height, d is the atmospheric duct thickness, and ΔN is the refractive index gradient of the atmospheric duct layer.

[0082] In the atmospheric duct layer:

[0083] M d is the absolute value of the waveguide intensity, which can be simplified in the evaporation waveguide to:

[0084] The trapping angle refers to the maximum emission elevation angle at which electromagnetic waves can be trapped by the atmospheric waveguide layer under specific atmospheric parameter conditions. Only electromagnetic waves with an emission elevation angle less than the trapping angle can achieve atmospheric waveguide propagation.

[0085]

[0086] If the electromagnetic wave source is located on the ground and total reflection occurs at the top of the waveguide, it can be simplified to

[0087]

[0088] The physics behind ray tracing in atmospheric waveguides is as follows:

[0089] In the two-dimensional case, the tropospheric atmospheric environment is regarded as an isotropic non-conductive layered medium, and a general time-harmonic field is considered:

[0090] E(r,t)=E0(r)e -iωt

[0091] Where r represents the position vector and E0 is the complex vector representing the position. Combined with Maxwell's equations in the region without current and charge:

[0092] curl H0+ik0εE0=0

[0093] curl E0-ik0μH0=0

[0094] divεE0=0

[0095] divμH0=0

[0096] Where ε is the dielectric constant, μ is the magnetic permeability, k0 = 2π / λ0, and λ0 is the vacuum wavelength.

[0097] In regions many wavelengths away from the source, the more general type of field can be expressed as follows:

[0098]

[0099] Where E represents the field strength, r represents the position vector, ζ(r) is the real scalar function of the position, and e(r) is the vector function of the position. When k0 is large (λ0 is small), Will satisfy the formula:

[0100] (gradζ) 2 =n 2

[0101] in Represents the refractive index. Function Often referred to as the eidetic function, the geometric wavefront is defined by ζ(r) = constant.

[0102] The geometric ray can now be defined as a trajectory perpendicular to the geometric wavefront. If r(s) represents the position vector of a point on the ray, considered as a function of the arc length s of the ray, then dr / ds=s, where is a unit vector.

[0103] Then the equation of the ray can be written as

[0104]

[0105] Then along the ray we have

[0106]

[0107] Then we can get the calculation formula of optical path

[0108]

[0109] That is, the optical length is equal to the product of the vacuum speed of light and the time required for light to propagate to s.

[0110] The principle of tracking the trajectory is as follows:

[0111] According to Snell's law of refraction, the atmospheric environment is uniformly layered in altitude, with the refractive index of each layer being n1, n2, n3, etc. In a two-dimensional rectangular coordinate system (x, z), the height of each layer is Δz, the distance segment is Δx, and the path segment is Δs. Both the distance segment and the path segment are variable. Rays propagating through different media obey Snell's law. Assuming Δz is a constant, when a source emits rays at a certain angle, the following relationship holds:

[0112]

[0113] The short horizontal distance of each layer and the path segment of the ray can be calculated using the trigonometric sine relationship:

[0114]

[0115]

[0116]

[0117] in, and represent the initial elevation angle and refraction angle of any layer, respectively.

[0118] The coordinates of each layer of the ray can be expressed as:

[0119] x(i+1)=x(i)+Δx i+1

[0120] z(i+1)=z(i)±Δz

[0121] The idea behind ray trajectory calculation is to cycle through each emission elevation angle at a fixed angle interval, then trace the propagation trajectory of the ray emitted at each elevation angle, and calculate all ray trajectories within the elevation angle range. Figure 7 Flowchart of ray tracing.

[0122] The energy calculation principle is the intensity law of geometric optics:

[0123] I1dS1=I2dS2

[0124] In general, consider any beam of light (curved or straight), the ratio of the intensity of any two points on a ray is as follows:

[0125]

[0126] Step 5: Compare the height of each ray at the horizontal distance of the receiving antenna (Rx) with the height of Rx. If the ray meets the conditions (the difference is within a certain range), it is considered as a possible eigenray.

[0127] An eigenray is defined as a ray that travels from a transmitter to a receiver via a certain path;

[0128] Step 6: For a line with a departure angle of The possible eigenrays of ( is the angle of the narrow ray tube), observe whether their heights at the horizontal distance Rx include Rx. If so, it is considered that an eigenray has been found;

[0129] Step 7: Screen all found eigenrays to find 2-4 eigenrays with obviously different paths;

[0130] Step 8: Each eigenray after screening is taken as the departure angle. For the central ray of the ray tube, calculate the maximum height (h) difference of all rays in the ray tube at the horizontal distance Rx to obtain the vertical cross-sectional width w of the ray tube;

[0131] The vertical cross-sectional width w of the X-ray tube is calculated as follows:

[0132] w=max{|h j1 -h j2 |}, j1, j2 = 1, 2, 3... The maximum value is the total number of rays in the ray tube

[0133] Step 9: Calculate the propagation factor of the path;

[0134] The formula for calculating the spread factor is as follows:

[0135]

[0136] Where L is the path length of the ray, w is the vertical cross-sectional width of the ray tube, is the flare angle of the narrow tube;

[0137] Step 10: Calculate the path loss, such as Figure 4 As shown in , parameters such as delay spread and arrival angle are Figure 5 、 Figure 6 As shown;

[0138] Delay spread is defined as the difference between the maximum transmission delay and the minimum transmission delay;

[0139] The angle of arrival is defined as: the angle between the wave ray and the horizontal direction;

[0140] The path loss is calculated as follows:

[0141] PL=(32.44+20log 10 r+20log 10 f)-20log 10 PF

[0142] Where PF is the propagation factor, r is the horizontal distance the ray travels, and f is the frequency.

[0143] In this embodiment, the number of rays is set to 10,000, and the initial departure angle is set to -89° to 89°. The method provided by the present invention is compared with the PE algorithm. The obtained ray trajectory tracing results, estimated path loss, relationship between time delay and distance, and distribution of estimated arrival angle in the evaporation waveguide environment are shown as follows: Figure 3 、 Figure 4 、 Figure 5 and Figure 6 As shown in Figure 2, within the line-of-sight range, the path loss estimated by RT matches well with that by PE; within the beyond-line-of-sight range, PE underestimates the path loss compared to RT.

[0144] Example 2

[0145] This embodiment provides a modeling system for evaporation waveguide beyond-horizon communication based on ray tracing.

[0146] The modeling system of evaporation waveguide beyond-horizon communication based on ray tracing includes:

[0147] The refractive index calculation module is configured to: calculate the vertical distribution of atmospheric thermodynamic temperature, atmospheric pressure, and water vapor pressure based on the set environmental parameters using the evaporation duct diagnostic model and combining basic meteorological elements at a certain altitude, thereby inverting the evaporation duct parameters to obtain the vertical distribution of the refractive index;

[0148] A ray trajectory construction module is configured to: trace ray trajectories based on the vertical distribution of refractive index. After the ray departs from the transmitting antenna at a certain departure angle, Snell's law is used to calculate the changing angles of incidence and refraction or reflection. The propagation of light in a stratified atmosphere is simulated by combining wavelength, altitude, distance, and delay data until the ray reaches a preset propagation distance or a maximum altitude, resulting in a complete ray trajectory.

[0149] a possible eigenray determination module, configured to: compare the height of each ray at a horizontal distance from the receiving antenna with the height of the receiving antenna to obtain possible eigenrays that meet preset conditions;

[0150] The eigenray determination module is configured to: for a ray with a departure angle of The possible eigenrays of If the heights of the two rays at the horizontal distance from the receiving antenna include the height of the receiving antenna, then the possible eigenray is an eigenray; wherein the eigenray is a ray that reaches the receiver from the transmitter through a certain path;

[0151] A screening module is configured to: screen all eigenrays to find a number of eigenrays with significantly different paths;

[0152] The modeling module is configured as follows: each eigenray after screening is used as a departure angle with an angle of The central ray of the ray tube is used to calculate the maximum height difference of all rays in the ray tube at the horizontal distance of the receiving antenna, and the vertical cross-sectional width of the ray tube is obtained. Based on this, the propagation factor, path loss, delay spread and arrival angle of each intrinsic ray are calculated, and the solid line communication model is constructed.

[0153] It should be noted that the examples and application scenarios implemented by the above-mentioned refractive index calculation module, ray trajectory construction module, possible eigenray determination module, eigenray determination module, screening module, and modeling module are the same as those in the steps of Example 1, but are not limited to the contents disclosed in the above-mentioned Example 1. It should be noted that the above-mentioned modules, as part of the system, can be executed in a computer system, such as a set of computer-executable instructions.

[0154] Example 3

[0155] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the steps in the ray tracing-based over-the-horizon emergency communication modeling of an evaporation waveguide are implemented as described in the first embodiment above.

[0156] Example 4

[0157] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps in the ray tracing-based over-the-horizon emergency communication modeling of an evaporation waveguide are implemented as described in the first embodiment above.

[0158] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage and optical storage, etc.) containing computer-usable program code.

[0159] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0160] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0161] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0162] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware through a computer program. The program can be stored in a computer-readable storage medium, and when executed, the program can include the processes in the above-described method embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0163] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A ray tracing-based modeling method for over-the-horizon emergency communication in an evaporation waveguide, characterized in that: include: Based on the set environmental parameters, the evaporation duct diagnostic model is used, combined with basic meteorological elements at a certain height, to calculate the vertical distribution of atmospheric thermodynamic temperature, atmospheric pressure, and water vapor pressure. This is used to invert the evaporation duct parameters and obtain the vertical distribution of refractive index. The ray trajectory is traced based on the vertical distribution of the refractive index. After the ray departs from the transmitting antenna at a certain departure angle, Snell's law is used to calculate the changing angles of incidence and refraction or reflection. The propagation of light in the layered atmosphere is simulated by combining wavelength, altitude, distance, and delay data until the light reaches the preset propagation distance or maximum limit altitude, resulting in a complete ray trajectory. Compare the height of each ray at the horizontal distance of the receiving antenna with the height of the receiving antenna to obtain possible eigenrays that meet the preset conditions; For a departure angle of The possible eigenrays of If the heights of the two rays at the horizontal distance from the receiving antenna include the height of the receiving antenna, then the possible eigenray is an eigenray; wherein the eigenray is a ray that reaches the receiver from the transmitter through a certain path; Screen all eigenrays and find several eigenrays with significantly different paths; Each eigenray after screening is taken as the departure angle. The central ray of the ray tube, calculates the maximum height difference of all rays in the ray tube at the horizontal distance of the receiving antenna, obtains the vertical cross-sectional width of the ray tube, and uses this to calculate the propagation factor, path loss, delay spread and arrival angle of each intrinsic ray, and constructs the solid line communication model; The process of obtaining a complete ray trajectory includes: According to Snell's law of refraction, the atmospheric environment height space is uniformly distributed in layers, and the atmospheric refractive index of each layer is set as ; In the two-dimensional rectangular coordinate system (x, z), the height of each layer is , the distance segment is , the path segment is , the distance segment and the path segment are variable; the ray satisfies Snell's law when propagating in different media, assuming is a constant, and the emitting source emits rays at a certain angle, the following relationship holds true: The short horizontal distance of each layer and the path segment of the ray are calculated using the trigonometric sine relationship: in, and represent the initial elevation angle and refraction angle of any layer respectively; The coordinates of each layer of the ray are expressed as: The idea behind ray trajectory calculation is to loop through each emission elevation angle at a fixed angle interval, then trace the propagation trajectory of the ray emitted at each elevation angle, and calculate all ray trajectories within the elevation range. The vertical cross-sectional width of the ray tube is: ； The propagation factor is Where L is the path length of the ray, is the vertical cross-sectional width of the tube, is the flare angle of the narrow tube; The path loss is: in, is the propagation factor, is the horizontal distance the ray travels, It's the frequency.

2. The ray tracing-based evaporation waveguide over-the-horizon emergency communication modeling method according to claim 1 is characterized in that: Before setting the environmental parameters, it also includes: initializing the environmental parameters including: initializing the initial departure angle range, maximum propagation height, maximum propagation distance, transmitting antenna height, carrier frequency, evaporation waveguide diagnostic model optional parameters, atmospheric temperature, sea surface temperature, wind speed, water vapor pressure, narrow ray tube initial departure angle and tracking step size.

3. The ray tracing-based evaporation waveguide over-the-horizon emergency communication modeling method according to claim 1 is characterized in that: The evaporation waveguide diagnostic model includes a BYC model, an NPS model, a PJ model, an MGB model or a pseudo-refractive index model.

4. The ray tracing-based evaporation waveguide over-the-horizon emergency communication modeling method according to claim 1 is characterized in that: Based on the vertical distribution of atmospheric thermodynamic temperature, atmospheric pressure and water vapor pressure, the evaporation duct parameters are inverted to obtain the distribution of the refractive index in the vertical direction, which specifically includes: The refractive index N is defined as: The atmospheric refractive index m and the atmospheric refractive index M are defined as: According to the refractive index index, atmospheric correction refractive index m and corrected atmospheric refractive index M, the refractive index gradient is obtained. and corrected refractive index gradient : in, is the atmospheric refractive index, T is the atmospheric thermodynamic temperature, P is the atmospheric pressure, e is the water vapor pressure, is the altitude from the Earth, is the average radius of the Earth.

5. A modeling system for evaporation waveguide over-the-horizon communication based on ray tracing, characterized in that: include: The refractive index calculation module is configured to: calculate the vertical distribution of atmospheric thermodynamic temperature, atmospheric pressure, and water vapor pressure based on the set environmental parameters using the evaporation duct diagnostic model and combining basic meteorological elements at a certain altitude, thereby inverting the evaporation duct parameters to obtain the vertical distribution of the refractive index; A ray trajectory construction module is configured to: trace ray trajectories based on the vertical distribution of refractive index. After the ray departs from the transmitting antenna at a certain departure angle, Snell's law is used to calculate the changing angles of incidence and refraction or reflection. The propagation of light in a stratified atmosphere is simulated by combining wavelength, altitude, distance, and delay data until the ray reaches a preset propagation distance or a maximum altitude, resulting in a complete ray trajectory. a possible eigenray determination module, configured to: compare the height of each ray at a horizontal distance from the receiving antenna with the height of the receiving antenna to obtain possible eigenrays that meet preset conditions; The eigenray determination module is configured to: for a ray with a departure angle of The possible eigenrays of If the heights of the two rays at the horizontal distance from the receiving antenna include the height of the receiving antenna, then the possible eigenray is an eigenray; wherein the eigenray is a ray that reaches the receiver from the transmitter through a certain path; A screening module is configured to: screen all eigenrays to find a number of eigenrays with significantly different paths; The modeling module is configured as follows: each eigenray after screening is used as a departure angle with an angle of The central ray of the ray tube, calculates the maximum height difference of all rays in the ray tube at the horizontal distance of the receiving antenna, obtains the vertical cross-sectional width of the ray tube, and uses this to calculate the propagation factor, path loss, delay spread and arrival angle of each intrinsic ray, and constructs the solid line communication model; The process of obtaining a complete ray trajectory includes: According to Snell's law of refraction, the atmospheric environment height space is uniformly distributed in layers, and the atmospheric refractive index of each layer is set as ; In the two-dimensional rectangular coordinate system (x, z), the height of each layer is , the distance segment is , the path segment is , the distance segment and the path segment are variable; the ray satisfies Snell's law when propagating in different media, assuming is a constant, and the emitting source emits rays at a certain angle, the following relationship holds true: The short horizontal distance of each layer and the path segment of the ray are calculated using the trigonometric sine relationship: in, and represent the initial elevation angle and refraction angle of any layer respectively; The coordinates of each layer of the ray are expressed as: The idea behind ray trajectory calculation is to loop through each emission elevation angle at a fixed angle interval, then trace the propagation trajectory of the ray emitted at each elevation angle, and calculate all ray trajectories within the elevation range. The vertical cross-sectional width of the ray tube is: ； The propagation factor is Where L is the path length of the ray, is the vertical cross-sectional width of the tube, is the flare angle of the narrow tube; The path loss is: in, is the propagation factor, is the horizontal distance the ray travels, It's the frequency.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the ray tracing-based evaporation waveguide over-the-horizon emergency communication modeling method according to any one of claims 1 to 4 are implemented.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the ray tracing-based evaporation waveguide beyond-horizon emergency communication modeling method according to any one of claims 1 to 4 are implemented.

Images