A method for modeling a geometric random channel for ground wave ocean over-the-horizon communication

Abstract

This invention discloses a geometric random channel modeling method for over-the-horizon (OTH) ground-wave ocean communication, relating to the technical field of channel modeling. The method includes: S1) establishing a high-frequency ground-wave ocean OTH simulation scenario and setting scenario layout parameters; S2) initializing the position parameters of the land-based transmitter and the sea-based receiver, as well as the parameters of the propagation medium, seawater; S3) calculating the large-scale parameters of the channel based on the set parameters; S4) calculating the path loss based on the set transmitter and receiver position information and the seawater medium parameter information; S5) calculating the small-scale parameters based on the angular expansion in the generated large-scale parameters, generating cluster delay and power, and generating corresponding channel coefficients; S6) updating the large-scale and small-scale parameters based on the transmitter and receiver motion and the cluster birth and death process, generating new channel coefficients; and S7) deriving and simulating the channel statistical characteristics based on the obtained channel coefficients. This invention can be used to simulate and analyze the channel characteristics of high-frequency ground-wave ocean communication scenarios.

Description

Technical Field

[0001] This invention relates to the technical field of channel modeling, and in particular to a geometric random channel modeling method for ground wave ocean over-the-horizon communication. Background Technology

[0002] The sixth generation (6G) mobile communication technology will expand from terrestrial communication to air-space-land-sea communication, achieving global communication coverage. With the rapid development of the blue ocean economy, satellite and commercially available marine communication systems operating in high-frequency bands are gradually emerging. Satellite marine communication systems offer high transmission rates, but the cost of equipment and services is high. Satellite communication is also affected by weather conditions, such as rainfall, which can cause severe attenuation and unstable signal reception. Shortwave communication offers advantages such as long coverage distances and low cost. It has good applications in maritime emergencies, maritime rescue, and long-range naval operations. Ground waves, as a shortwave communication mode, are not affected by ionospheric disturbances or weather conditions, resulting in a more stable communication link. Furthermore, due to the excellent conductivity of the sea surface, ground wave transmission attenuation is much less than that on land, allowing for a communication coverage range of approximately 1000 km over the sea, almost covering the entire South China Sea.

[0003] Research on high-frequency ground wave over-the-horizon (OTH) communication in marine environments is a crucial component in achieving the integrated air-space-ground-sea communication goal of 6G. Its achievements will directly promote the development of the marine economy and enhance maritime safety. By addressing communication challenges in the marine environment and constructing an efficient and reliable high-frequency ground wave OTH communication system, strong technical support will be provided for global maritime activities. Channel modeling, as the foundation of communication system design and optimization, allows for a better understanding of signal propagation characteristics, optimization of system performance, reduction of development costs, and promotion of new technology applications through accurate channel modeling. For ground wave communication in the marine environment, accurate and effective channel modeling is fundamental. Therefore, proposing an accurate shore-to-ship marine ground wave wireless channel model is an urgent problem to be solved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a geometric random channel modeling method for ground wave ocean over-line-of-sight communication, which can characterize the channel characteristics in this communication scenario.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A geometric random channel modeling method for ground-wave ocean over-the-horizon communication proposed according to the present invention includes:

[0007] Step S1: Establish a high-frequency ground wave ocean communication simulation scenario and set the scenario layout parameters;

[0008] Step S2: Initialize the positions of the land-based transmitter and the sea-based receiver, as well as the seawater medium parameters;

[0009] Step S3: Calculate the large-scale parameters of the channel based on the scene layout parameters and seawater medium parameters set in steps S1 and S2.

[0010] Step S4: Calculate the propagation path loss based on the set locations of the land-based transmitter and the sea-based receiver, and calculate the path loss caused by the diffraction of ground waves through seawater based on the set seawater medium parameters.

[0011] Step S5: Calculate the small-scale parameters based on the angle spread in the generated large-scale parameters, initialize the position of the scattering cluster at the land transmitter and the sea receiver respectively, generate the cluster's delay and power, and generate the channel coefficients by combining the path loss calculated in step S4.

[0012] Step S6: Based on the motion of the transceiver and the birth and death process of the cluster, update the large-scale parameters and small-scale parameters to generate new channel coefficients;

[0013] Step S7: Derive and simulate the channel statistical characteristics based on the obtained new channel coefficients.

[0014] As a further optimization of the geometric random channel modeling method for ground-wave ocean over-the-horizon communication described in this invention, step S1 includes:

[0015] Step S101: The land-based transmitter is a land-based base station, and the sea-based receiver is a ship at sea;

[0016] Step S102: Both the transceiver and receiver are configured as multi-antenna average linear arrays, and the land-based transmitter has a total of Root antenna, The land-based launch terminal is represented by the first The azimuth angle of the antenna array at the land-based transmitting end is [missing information]. The pitch angle is The first land-based launch terminal The th cluster The azimuth angle of each diameter is The pitch angle is The maritime receiving end has a total of Root antenna, The first term of the receiving end at sea The azimuth angle of the antenna array at the marine receiving end is [missing information]. The pitch angle is The first at the sea receiving end The th cluster The azimuth angle of each diameter is The pitch angle is ;

[0017] Step S103: In establishing a high-frequency ground wave ocean communication simulation scenario, the carrier frequency is... The initial number of clusters is , No. The number of sub-diameters of each cluster is .

[0018] As a further optimization of the geometric random channel modeling method for ground-wave ocean over-the-horizon communication described in this invention, step S2 includes:

[0019] Step S201: Initialize the initial position coordinates of the land-based transmitter and the sea-based receiver, and calculate the communication distance;

[0020] The distance at which the Loss of Sight (LoS) path disappears is calculated based on the heights of the land-based transmitter and the sea-based receiver antennas, thus determining the location of channel scattering clusters generated when high-frequency ground waves achieve beyond-line-of-sight communication via diffraction; the distance at which the LoS path disappears. for:

[0021]

[0022] in, Indicates the height of the antenna at the land-based transmitter. Indicates the height of the receiving antenna at sea. Represents the radius of the Earth;

[0023] Initialize the seawater medium parameters and define the dielectric constant as follows: conductivity .

[0024] As a further optimization of the geometric random channel modeling method for ground-wave ocean over-the-horizon communication described in this invention, step S3 includes:

[0025] Based on the transmitter elevation angle in the scene layout parameters, different means and variances are selected to generate large-scale parameters with spatial consistency: delay spread (DS), azimuth angle of arrival spread (ASA), elevation angle of arrival spread (ESA), Rice factor (KF), and cross-polarization ratio (XPR). Azimuth departure spread (ASD) and elevation departure spread (ESD) are considered to be 0. Among the large-scale parameters, KF and XPR follow a normal distribution, while the rest follow a log-normal distribution.

[0026] As a further optimization of the geometric random channel modeling method for over-the-horizon ocean communication described in this invention, step 4, calculating the propagation path loss based on the established location information of the land-based transmitter and the sea-based receiver, includes:

[0027] Step S401: Calculate the path loss model for diffraction on the Earth's surface due to the Earth's curvature at the set initial communication distance, as follows:

[0028]

[0029] in, For diffraction path loss, The normalized communication distance is calculated as follows:

[0030]

[0031] in, Indicates communication distance. These are parameters related to the ground and polarization type;

[0032]

[0033] in, The normalization factor representing the impedance of the Earth's surface, for different types of polarized antennas. The calculation is as follows:

[0034]

[0035]

[0036] in, and These represent the horizontal and vertical polarization of the antenna, respectively.

[0037] Step S402: Since the height of the transmitting and receiving antennas is also related to the diffraction propagation loss, the corresponding diffraction loss is expressed as:

[0038]

[0039]

[0040] in, and These represent the diffraction losses caused by altitude during propagation at the land-based transmitting antenna and the sea-based receiving antenna, respectively. and , , It is a parameter related to antenna height. and These represent the normalized altitudes of the land-based transmitter and the sea-based receiver antennas, respectively; finally, by combining the above derivation processes, the total path loss is... The calculation is as follows:

[0041] .

[0042] As a further optimization of the geometric random channel modeling method for ground-wave ocean over-the-horizon communication described in this invention, step S5 includes:

[0043] Step S501: Using the scene layout parameters set in steps S1 and S2 and the initialized position parameters of the land transmitter and sea receiver, then... Time delay for generating intra-cluster sub-paths :

[0044]

[0045] in, Represents the speed of light. Indicates the time delay between clusters, Indicates in The sum of the distances between the clusters near the land-based transmitter and the land-based transmitter at any given time, and the distances between the clusters near the sea-based receiver and the sea-based receiver, is expressed as:

[0046]

[0047] in, Indicates in The first maritime receiving terminal root antenna and the first The distance of each path scattering cluster, Indicates in The first maritime receiving terminal root antenna and the first The time delay of each path scattering cluster and They are represented as follows:

[0048]

[0049]

[0050] in, This represents the distance where the line-of-sight path disappears. and Let represent the adjustable distances of clusters near the land-based transmitter and the adjustable distances of clusters near the sea-based receiver, respectively; then, the time delay between clusters... The calculation is as follows:

[0051]

[0052] in, This indicates adjustable random delay. Indicates in The distance between clusters near the land-based transmitter and clusters near the sea-based receiver at any given time;

[0053] Step S502: Generate the power of the cluster. The power of the cluster follows a single-slope exponential distribution as follows:

[0054]

[0055] in, Indicates in The power of the cluster median diameter at time t, , The shadow decay of the cluster is represented by the cluster's shadow decay. Indicates delay extension, Indicates the delay factor. It follows a normal distribution with an expected value of 0 and a variance of . where e is the natural base;

[0056] Step S503: Generate the cross-polarization ratio XPR of the sub-path, which follows a log-normal distribution as follows:

[0057]

[0058] in, , For the first The first cluster The logarithmic form of the cross-polarization ratio of individual diameters and These are the mean and variance of the cross-polarization ratio, respectively. Follows a normal distribution. The cross-polarization ratio for generating sub-paths;

[0059] Step S504: Based on the cluster parameters generated in steps S501-S503, obtain the position vector of each cluster according to the arrival pitch angle and arrival azimuth angle, and obtain the specific location of the cluster according to the time delay spread;

[0060] Step S505: Calculate the small-scale parameters based on the angular spread in the generated large-scale parameters to generate channel coefficients. as follows:

[0061] ;

[0062] in, , and These represent the number of antennas at the land-based transmitter and the sea-based receiver, respectively. root antenna and the first Channel impulse response between root antennas Represented as:

[0063] The channel impulse response under the dual-cluster architecture is as follows: ;

[0064] in, Represents small-scale channel elements. Represents small-scale channel coefficients. It is a common polarity imbalance factor. This indicates an indicator function, where j is the imaginary unit. and They represent The number of time clusters and the number of sub-paths in each cluster, Indicates the cross-polarization ratio; , , and These represent the land-based transmitter and the sea-based receiver, respectively. The first cluster The arrival pitch angle, arrival azimuth angle, departure pitch angle, and departure azimuth angle of the individual diameter; , , and They represent the first The first cluster Random phases of the sub-diameter in the vertical-vertical, vertical-horizontal, horizontal-vertical, and horizontal-horizontal directions; This refers to the vertical polarization mode of the receiving antenna at sea. This refers to the horizontal polarization mode of the marine receiver antenna; the superscript T indicates transpose operation. This refers to the vertical polarization mode of the land-based transmitting antenna. The horizontal polarization mode for the land-based transmitting antenna;

[0065] Indicates the first root transmitting antenna and the first Between the root receiving antennas The first cluster Power of the individual diameter.

[0066] As a further optimization of the geometric random channel modeling method for ground-wave ocean over-the-horizon communication described in this invention, step S6 includes:

[0067] Step S601: Introduce the cluster birth and death process to characterize the evolution of clusters in the time domain, frequency domain, and spatial domain. The number of newly formed clusters is calculated as follows:

[0068]

[0069] in, The number of new clusters, Indicates the expectation. For spatial sampling interval, The time-domain sampling interval, The frequency domain sampling interval; and These represent the cluster generation rate and the cluster destruction rate, respectively. The probability of being a newly formed cluster;

[0070] Step S602: Based on the change in the number of clusters at different times, calculate the channel coefficients at different times through step S5.

[0071] As a further optimization scheme for the geometric random channel modeling method for over-the-horizon ocean communication based on ground wave waves described in this invention, the channel statistical characteristics in step S7 include the time autocorrelation function, Doppler power spectral density, and root mean square delay spread, and include the following steps:

[0072] Step S701: Perform a Fourier transform on the channel coefficients generated in step S5 to obtain the channel transformation function. The calculation is as follows:

[0073]

[0074] in, Represents frequency variables. Represents a time variable;

[0075] Will exist Sampling conjugate channel conversion function To calculate the time cross-correlation function:

[0076]

[0077] in, This is the time autocorrelation function;

[0078] Step S702: Calculate the root mean square delay spread of the channel. , is represented as:

[0079]

[0080] in, Indicates the average delay. The delayed power spectral density is expressed as:

[0081]

[0082] in, Represents normalized power;

[0083] Step S703: Calculate the channel Doppler power spectral density It is obtained by taking the Fourier transform of the time autocorrelation function:

[0084]

[0085] in, Indicates Doppler frequency shift, This is the time autocorrelation function.

[0086] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0087] This invention is applicable to communication channel modeling in 3-20MHz frequency band ground wave over-the-horizon marine scenarios. Based on establishing a high-frequency ground wave over-the-horizon marine communication scenario, this invention sets scenario layout parameters, initializes the position information of the transmitter and receiver, and antenna height information; supports the movement characteristics of the transmitter, receiver, and cluster; considers the spatial consistency of large-scale parameters; considers the sparsity of clusters in marine communication scenarios; for large-scale fading, it considers the path loss caused by diffraction of ground waves propagating over the sea surface and the path loss caused by the seawater medium; calculates the cluster's time delay, angle, and power by calculating the geometric position information of the cluster and scatterers, generating channel coefficients; introduces the cluster's birth and death process to characterize its evolution in the time and frequency domains, and derives channel statistical characteristics for simulation analysis; this model simultaneously considers the channel characteristics of high-frequency ground wave over-the-horizon marine communication scenarios and is applicable to channel characteristic simulation of high-frequency ground wave over-the-horizon marine communication scenarios. Attached Figure Description

[0088] Figure 1 This is a flowchart illustrating a geometric random channel modeling method for high-frequency ground wave ocean over-the-horizon communication provided in this embodiment.

[0089] Figure 2 This is a schematic diagram of the geometric random channel model for high-frequency ground wave maritime communication provided in this embodiment;

[0090] Figure 3 The figure shows the results of comparing the proposed path loss models with measurement data at different frequencies.

[0091] Figure 4 Doppler power spectral density results for proposed channel models at different speeds and frequencies;

[0092] Figure 5 The time autocorrelation function results of the proposed channel model under different frequencies and antenna configurations are shown in the figure.

[0093] Figure 6 The cumulative distribution function results of the root mean square time delay spread under different frequencies and different numbers of scattering clusters are shown in the figure. Detailed Implementation

[0094] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0095] See Figure 1 and Figure 2 This embodiment provides a geometric random channel modeling method for high-frequency ground wave ocean over-the-horizon communication proposed by the present invention. The channel modeling method includes the following steps:

[0096] Step S1: Establish a high-frequency ground wave ocean communication simulation scenario and set the scenario layout parameters;

[0097] Step S2: Initialize the positions of the land-based transmitter and the sea-based receiver, as well as the seawater medium parameters;

[0098] Step S3: Calculate the large-scale parameters of the channel based on the scene layout parameters and seawater medium parameters set in steps S1 and S2.

[0099] Step S4: Calculate the propagation path loss based on the set locations of the land-based transmitter and the sea-based receiver, and calculate the path loss caused by the diffraction of ground waves through seawater based on the set seawater medium parameters.

[0100] Step S5: Calculate the small-scale parameters based on the angle spread in the generated large-scale parameters, initialize the position of the scattering cluster at the land transmitter and the sea receiver respectively, generate the cluster's delay and power, and generate the channel coefficients by combining the path loss calculated in step S4.

[0101] Step S6: Based on the motion of the transceiver and the birth and death process of the cluster, update the large-scale parameters and small-scale parameters to generate new channel coefficients;

[0102] Step S7: Based on the obtained new channel coefficients, derive and simulate the channel statistical characteristics.

[0103] Furthermore, step S1 specifically includes the following steps:

[0104] Step S101: The land-based transmitter is a land-based base station, and the sea-based receiver is a ship at sea;

[0105] Step S102: Both the transceiver and receiver are configured as multi-antenna average linear arrays, and the land-based transmitter has a total of Root antenna, The land-based launch terminal is represented by the first The azimuth angle of the antenna array at the land-based transmitting end is [missing information]. The pitch angle is The first land-based launch terminal The th cluster The azimuth angle of each diameter is The pitch angle is The maritime receiving end has a total of Root antenna, The first term of the receiving end at sea The azimuth angle of the antenna array at the marine receiving end is [missing information]. The pitch angle is The first at the sea receiving end The th cluster The azimuth angle of each diameter is The pitch angle is ;

[0106] Step S103: In establishing a high-frequency ground wave ocean communication simulation scenario, the carrier frequency is... The initial number of clusters is , No. The number of sub-diameters of each cluster is .

[0107] Furthermore, step S2 specifically includes:

[0108] Step S201: Initialize the initial position coordinates of the land-based transmitter and the sea-based receiver, and calculate the communication distance;

[0109] The distance at which the Loss of Sight (LoS) path disappears is calculated based on the heights of the land-based transmitter and the sea-based receiver antennas, thus determining the location of channel scattering clusters generated when high-frequency ground waves achieve beyond-line-of-sight communication via diffraction; the distance at which the LoS path disappears. for:

[0110]

[0111] in, Indicates the height of the antenna at the land-based transmitter. Indicates the height of the receiving antenna at sea. This represents the radius of the Earth.

[0112] Initialize the seawater medium parameters and define the dielectric constant as follows: conductivity .

[0113] Furthermore, step S3 specifically includes the following steps:

[0114] Step S301: Based on the transmitter elevation angle in the scene layout parameters, select different means and variances to generate large-scale parameters with spatial consistency: delay spread DS, azimuth angle of arrival spread ASA, elevation angle of arrival spread ESA, Rice factor KF, and cross-polarization ratio XPR; departure azimuth angle spread ASD and departure elevation angle spread ESD are considered to be 0. Among the large-scale parameters, KF and XPR follow a normal distribution, and the rest follow a log-normal distribution.

[0115] Furthermore, step S4 specifically includes the following steps:

[0116] Step S401: Calculate the path loss model for diffraction on the Earth's surface due to the Earth's curvature at the set initial communication distance, as follows:

[0117]

[0118] in, For diffraction path loss, The normalized communication distance is calculated as follows:

[0119]

[0120] in, Indicates communication distance. These are parameters related to the ground and polarization type:

[0121]

[0122] in, The normalization factor representing the impedance of the Earth's surface, for different types of polarized antennas. The calculation is as follows:

[0123]

[0124]

[0125] in, and These represent the horizontal and vertical polarization of the antenna, respectively.

[0126] Step S402: Since the height of the transmitting and receiving antennas is also related to the diffraction propagation loss, the corresponding diffraction loss can be expressed as:

[0127]

[0128]

[0129] in, and These represent the diffraction losses caused by altitude during propagation at the land-based transmitting antenna and the sea-based receiving antenna, respectively. and , , It is a parameter related to antenna height. and These represent the normalized altitudes of the land-based transmitter and the sea-based receiver antennas, respectively; finally, by combining the above derivation processes, the total path loss is... The calculation is as follows:

[0130]

[0131] Furthermore, step S5 specifically includes:

[0132] Step S501: Using the scene layout parameters set in steps S1 and S2 and the initialized position parameters of the land transmitter and sea receiver, then... Time delay for generating intra-cluster sub-paths :

[0133]

[0134] in, Represents the speed of light. Indicates the time delay between clusters, Indicates in The sum of the distances between the clusters near the land-based transmitter and the land-based transmitter at any given time, and the distances between the clusters near the sea-based receiver and the sea-based receiver, is expressed as:

[0135]

[0136] in, Indicates in The first maritime receiving terminal root antenna and the first The distance of each path scattering cluster, Indicates in The first maritime receiving terminal root antenna and the first The time delay of each path scattering cluster and They are represented as follows:

[0137]

[0138]

[0139] in, This represents the distance where the line-of-sight path disappears. and Let represent the adjustable distances of clusters near the land-based transmitter and the adjustable distances of clusters near the sea-based receiver, respectively; then, the time delay between clusters... The calculation is as follows:

[0140]

[0141] in, This indicates adjustable random delay. Indicates in The distance between clusters near the land-based transmitter and clusters near the sea-based receiver at any given time;

[0142] Step S502: Generate the power of the cluster. The power of the cluster follows a single-slope exponential distribution as follows:

[0143]

[0144] in, Indicates in The power of the cluster median diameter at time t, The shadow decay of the cluster is represented by the cluster's shadow decay. Indicates delay extension, Indicates the delay factor. It follows a normal distribution with an expected value of 0 and a variance of . where e is the natural base;

[0145] Step S503: Generate the cross-polarization ratio XPR of the sub-path, which follows a log-normal distribution as follows:

[0146]

[0147] in, , For the first The first cluster The logarithmic form of the cross-polarization ratio of individual diameters and These are the mean and variance of the cross-polarization ratio, respectively. Follows a normal distribution. The cross-polarization ratio for generating sub-paths;

[0148] Step S504: Based on the cluster parameters generated in steps S501-S503, obtain the position vector of each cluster according to the arrival pitch angle and arrival azimuth angle, and obtain the specific location of the cluster according to the time delay spread;

[0149] Step S505: Calculate the small-scale parameters based on the angular spread in the generated large-scale parameters to generate channel coefficients. as follows:

[0150] ;

[0151] in, , and These represent the number of antennas at the land-based transmitter and the sea-based receiver, respectively. root antenna and the first Channel impulse response between root antennas Represented as:

[0152] The channel impulse response under the dual-cluster architecture is as follows:

[0153] ;

[0154] in, Represents small-scale channel elements. Represents small-scale channel coefficients. Common polarity imbalance factor This indicates an indicator function, where j is the imaginary unit. and They represent The number of time clusters and the number of sub-paths in each cluster, Indicates the cross-polarization ratio; , , and These represent the land-based transmitter and the sea-based receiver, respectively. The first cluster The arrival pitch angle, arrival azimuth angle, departure pitch angle, and departure azimuth angle of the individual diameter; , , and They represent the first The first cluster Random phases of the sub-diameter in the vertical-vertical, vertical-horizontal, horizontal-vertical, and horizontal-horizontal directions; This refers to the vertical polarization mode of the receiving antenna at sea. This refers to the horizontal polarization mode of the marine receiver antenna; the superscript T indicates transpose operation. This refers to the vertical polarization mode of the land-based transmitting antenna. The horizontal polarization mode for the land-based transmitting antenna;

[0155] Indicates the first root transmitting antenna and the first Between the root receiving antennas The first cluster Power per unit diameter

[0156] Furthermore, step S6 specifically includes the following steps:

[0157] Step S601: Introduce the cluster birth and death process to characterize the evolution of clusters in the time domain, frequency domain, and spatial domain. The number of newly formed clusters is calculated as follows:

[0158]

[0159] in, The number of new clusters, Indicates the expectation. For spatial sampling interval, The time-domain sampling interval, The frequency domain sampling interval; and These represent the cluster generation rate and the cluster destruction rate, respectively. The probability of being a newly formed cluster;

[0160] Step S602: Based on the change in the number of clusters at different times, calculate the channel coefficients at different times through step S5.

[0161] Furthermore, step S7 specifically includes:

[0162] Step S701: Perform a Fourier transform on the channel coefficients generated in step S5 to obtain the channel transformation function. The calculation is as follows:

[0163]

[0164] in, Represents frequency variables. Represents a time variable;

[0165] Will exist Sampling conjugate channel conversion function To calculate the time cross-correlation function:

[0166]

[0167] in, This is the time autocorrelation function;

[0168] Step S702: Calculate the root mean square delay spread of the channel. , is represented as:

[0169]

[0170] in, Indicates the average delay. The delayed power spectral density is expressed as:

[0171]

[0172] in, Represents normalized power;

[0173] Step S703: Calculate the channel Doppler power spectral density It is obtained by taking the Fourier transform of the time autocorrelation function:

[0174]

[0175] in, Indicates Doppler frequency shift, This is the time autocorrelation function.

[0176] Figure 3 The comparison between the proposed path loss model and the measurement data under different communication frequencies shows that the proposed channel model has a high fitting effect with the corresponding measurement data, verifying the accuracy of the proposed path loss model. Figure 4 The comparison of the normalized Doppler power spectral density of the proposed channel model at different speeds and frequencies shows that at the same speed, the main lobe narrows as the frequency decreases; while at the same frequency configuration, the main lobe widens and the high-frequency tail strengthens as the speed increases. Figure 5 The comparison of the time autocorrelation function of the proposed channel model under different frequencies and antenna configurations shows that at the same frequency, increasing the number of antennas leads to a slower change in the autocorrelation function, which is attributed to spatial nonstationarity. Figure 6 By comparing the cumulative distribution functions representing the root mean square delay spread under different frequencies and numbers of scattering clusters, it can be found that the time delay spread of ground wave maritime over-the-horizon communication is on the order of microseconds.

[0177] In summary, this invention proposes a three-dimensional geometrically random ground-wave ocean over-the-horizon communication channel modeling method, applicable to channel modeling in ground-wave over-the-horizon ocean scenarios. The model considers the birth and death variations of scattering clusters over the LoS path vanishing distance and derives channel parameters such as delay and power. Furthermore, it considers the mobility of the transmitter and receiver and the clusters, as well as the cluster birth and death processes in the time and frequency domains. This invention can be used to simulate the statistical characteristics of high-frequency ground-wave ocean over-the-horizon communication, including path loss, time autocorrelation function, root mean square delay spread, and normalized Doppler power spectral density, providing a foundation for channel analysis and system design research in high-frequency ground-wave ocean over-the-horizon communication scenarios.

[0178] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A geometric random channel modeling method for ground-wave ocean over-the-horizon communication, characterized in that, include: Step S1: Establish a high-frequency ground wave ocean communication simulation scenario and set the scenario layout parameters; Step S2: Initialize the positions of the land-based transmitter and the sea-based receiver, as well as the seawater medium parameters; Step S3: Calculate the large-scale parameters of the channel based on the scene layout parameters and seawater medium parameters set in steps S1 and S2. Step S4: Calculate the propagation path loss based on the set locations of the land-based transmitter and the sea-based receiver, and calculate the path loss caused by the diffraction of ground waves through seawater based on the set seawater medium parameters. Step S5: Calculate the small-scale parameters based on the angle spread in the generated large-scale parameters, initialize the position of the scattering cluster at the land transmitter and the sea receiver respectively, generate the cluster's delay and power, and generate the channel coefficients by combining the path loss calculated in step S4. Step S6: Based on the motion of the transceiver and the birth and death process of the cluster, update the large-scale parameters and small-scale parameters to generate new channel coefficients; Step S7: Derive and simulate the channel statistical characteristics based on the obtained new channel coefficients.

2. The geometric random channel modeling method for ground-wave ocean over-the-horizon communication according to claim 1, characterized in that, Step S1 includes: Step S101: The land-based transmitter is a land-based base station, and the sea-based receiver is a ship at sea; Step S102: Both the transceiver and receiver are configured as multi-antenna average linear arrays, and the land-based transmitter has a total of Root antenna, The land-based launch terminal is represented by the first The azimuth angle of the antenna array at the land-based transmitting end is [missing information]. The pitch angle is The first land-based launch terminal The th cluster The azimuth angle of each diameter is The pitch angle is The maritime receiving end has a total of Root antenna, The first term of the receiving end at sea The azimuth angle of the antenna array at the marine receiving end is [missing information]. The pitch angle is The first at the sea receiving end The th cluster The azimuth angle of each diameter is The pitch angle is ; Step S103: In establishing a high-frequency ground wave ocean communication simulation scenario, the carrier frequency is... The initial number of clusters is , No. The number of sub-diameters of each cluster is .

3. The geometric random channel modeling method for ground-wave ocean over-the-horizon communication according to claim 1, characterized in that, Step S2 includes: Step S201: Initialize the initial position coordinates of the land-based transmitter and the sea-based receiver, and calculate the communication distance; The distance at which the Loss of Sight (LoS) path disappears is calculated based on the heights of the land-based transmitter and the sea-based receiver antennas, thus determining the location of channel scattering clusters generated when high-frequency ground waves achieve beyond-line-of-sight communication via diffraction; the distance at which the LoS path disappears. for: ； in, Indicates the height of the antenna at the land-based transmitter. Indicates the height of the receiving antenna at sea. Represents the radius of the Earth; Initialize the seawater medium parameters and define the dielectric constant as follows: conductivity .

4. The geometric random channel modeling method for ground-wave ocean over-the-horizon communication according to claim 1, characterized in that, Step S3 includes: Based on the transmitter elevation angle in the scene layout parameters, different means and variances are selected to generate large-scale parameters with spatial consistency: delay spread (DS), azimuth angle of arrival spread (ASA), elevation angle of arrival spread (ESA), Rice factor (KF), and cross-polarization ratio (XPR). Azimuth departure spread (ASD) and elevation departure spread (ESD) are considered to be 0. Among the large-scale parameters, KF and XPR follow a normal distribution, while the rest follow a log-normal distribution.

5. A geometric random channel modeling method for ground-wave ocean over-the-horizon communication according to claim 3, characterized in that, In step 4, the propagation path loss is calculated based on the location information of the land-based transmitter and the sea-based receiver, including: Step S401: Calculate the path loss model for diffraction on the Earth's surface due to the Earth's curvature at the set initial communication distance, as follows: ； in, For diffraction path loss, The normalized communication distance is calculated as follows: ； in, Indicates communication distance. These are parameters related to the ground and polarization type; ； in, The normalization factor representing the impedance of the Earth's surface, for different types of polarized antennas. The calculation is as follows: ； ； in, and These represent the horizontal and vertical polarization of the antenna, respectively. Step S402: Since the height of the transmitting and receiving antennas is also related to the diffraction propagation loss, the corresponding diffraction loss is expressed as: ； ； in, and These represent the diffraction losses caused by altitude during propagation at the land-based transmitting antenna and the sea-based receiving antenna, respectively. and , , It is a parameter related to antenna height. and These represent the normalized altitudes of the land-based transmitter and the sea-based receiver antennas, respectively; finally, by combining the above derivation processes, the total path loss is... The calculation is as follows: 。 6. A geometric random channel modeling method for ground-wave ocean over-the-horizon communication according to claim 5, characterized in that, Step S5 includes: Step S501: Using the scene layout parameters set in steps S1 and S2 and the initialized position parameters of the land transmitter and sea receiver, then... Time delay for generating intra-cluster sub-paths : ； in, Represents the speed of light. Indicates the time delay between clusters, Indicates in The sum of the distances between the clusters near the land-based transmitter and the land-based transmitter at any given time, and the distances between the clusters near the sea-based receiver and the sea-based receiver, is expressed as: ； in, Indicates in The first maritime receiving terminal root antenna and the first The distance of each path scattering cluster, Indicates in The first maritime receiving terminal root antenna and the first The time delay of each path scattering cluster and They are represented as follows: ； ； in, This represents the distance where the line-of-sight path disappears. and Let represent the adjustable distances of clusters near the land-based transmitter and the adjustable distances of clusters near the sea-based receiver, respectively; then, the time delay between clusters... The calculation is as follows: ； in, This indicates adjustable random delay. Indicates in The distance between clusters near the land-based transmitter and clusters near the sea-based receiver at any given time; Step S502: Generate the power of the cluster. The power of the cluster follows a single-slope exponential distribution as follows: ； in, Indicates in The power of the cluster median diameter at time t, , The shadow decay of the cluster is represented by the cluster's shadow decay. Indicates delay extension, Indicates the delay factor. It follows a normal distribution with an expected value of 0 and a variance of . where e is the natural base; Step S503: Generate the cross-polarization ratio XPR of the sub-path, which follows a log-normal distribution as follows: ； in, , For the first The first cluster The logarithmic form of the cross-polarization ratio of individual diameters and These are the mean and variance of the cross-polarization ratio, respectively. Follows a normal distribution. The cross-polarization ratio for generating sub-paths; Step S504: Based on the cluster parameters generated in steps S501-S503, obtain the position vector of each cluster according to the arrival pitch angle and arrival azimuth angle, and obtain the specific location of the cluster according to the time delay spread; Step S505: Calculate the small-scale parameters based on the angular spread in the generated large-scale parameters to generate channel coefficients. as follows: ； in, , and These represent the number of antennas at the land-based transmitter and the sea-based receiver, respectively. root antenna and the first Channel impulse response between root antennas Represented as: The channel impulse response under the dual-cluster architecture is as follows: ； in, Represents small-scale channel elements. Represents small-scale channel coefficients. It is a common polarity imbalance factor. This indicates an indicator function, where j is the imaginary unit. and They represent The number of time clusters and the number of sub-paths in each cluster, Indicates the cross-polarization ratio; , , and These represent the land-based transmitter and the sea-based receiver, respectively. The first cluster The arrival pitch angle, arrival azimuth angle, departure pitch angle, and departure azimuth angle of the individual diameter; , , and They represent the first The first cluster Random phases of the sub-diameter in the vertical-vertical, vertical-horizontal, horizontal-vertical, and horizontal-horizontal directions; This refers to the vertical polarization mode of the receiving antenna at sea. This refers to the horizontal polarization mode of the marine receiver antenna; the superscript T indicates transpose operation. This refers to the vertical polarization mode of the land-based transmitting antenna. The horizontal polarization mode for the land-based transmitting antenna; Indicates the first root transmitting antenna and the first Between the root receiving antennas The first cluster Power of the individual diameter.

7. A geometric random channel modeling method for ground-wave ocean over-the-horizon communication according to claim 6, characterized in that, Step S6 includes: Step S601: Introduce the cluster birth and death process to characterize the evolution of clusters in the time domain, frequency domain, and spatial domain. The number of newly formed clusters is calculated as follows: ； in, The number of new clusters, Indicates the expectation. For spatial sampling interval, The time-domain sampling interval, The frequency domain sampling interval; and These represent the cluster generation rate and the cluster destruction rate, respectively. The probability of being a newly formed cluster; Step S602: Based on the change in the number of clusters at different times, calculate the channel coefficients at different times through step S5.

8. A geometric random channel modeling method for ground-wave ocean over-the-horizon communication according to claim 6, characterized in that, The channel statistical characteristics in step S7 include the time autocorrelation function, Doppler power spectral density, and root mean square delay spread, and include the following steps: Step S701: Perform a Fourier transform on the channel coefficients generated in step S5 to obtain the channel transformation function. The calculation is as follows: ； in, Represents frequency variables. Represents a time variable; Will exist Sampling conjugate channel conversion function To calculate the time cross-correlation function: ； in, This is the time autocorrelation function; Step S702: Calculate the root mean square delay spread of the channel. , represented as: ； in, Indicates the average delay. The delayed power spectral density is expressed as: ； in, Represents normalized power; Step S703: Calculate the channel Doppler power spectral density It is obtained by taking the Fourier transform of the time autocorrelation function: ； in, Indicates Doppler frequency shift, This is the time autocorrelation function.

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