Atmospheric absorption loss simplified calculation method based on ground-to-air interference coexistence scene

Abstract

The invention discloses a simplified calculation method for atmospheric absorption loss based on a ground-to-air interference coexistence scene, and belongs to the field of satellite communication loss. The method specifically comprises the following steps: firstly, constructing a visual area forming an interference link for a satellite on the surface of the earth, performing grid division on the visual area according to longitude and latitude, and determining a central point of each area; the elevation angles of different areas relative to the satellite are determined according to the position relation between each center point and the satellite; then, according to the dimensions, three different atmosphere layering models of middle, low and high are determined, and radio wave signals of 0-350 GHz frequency bands can be covered; when satellite signals pass through different atmosphere layering models, actual path lengths of the satellite signals passing through each atmosphere layer of each model are calculated respectively; calculating the absorption loss value of each atmospheric layer when the satellite signal passes through the atmospheric layering model; and finally, atmospheric absorption loss values in the frequency range of 0-350GHz in regions with different latitudes and elevation angles are output. According to the invention, the atmospheric absorption loss efficiency is improved, and the resource consumption is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of satellite communication signal loss, and specifically is a simplified calculation method for atmospheric absorption loss in a ground-to-air interference coexistence scenario. Background Art

[0002] With the continuous development of satellite communication technology, the interference coexistence problem has gradually become an important research field between satellite and terrestrial communication systems.

[0003] In the coexistence scenario of satellites and ground communication systems, especially when the frequency bands of systems such as satellite communications, 5G and LTE overlap or are closely adjacent, satellites are not only subject to interference signals generated by various communication systems on the surface of the earth, but may also be subject to electromagnetic interference caused by various infrastructure equipment (such as radar, satellite navigation systems, etc.); these interference signals are transmitted to the satellite through the atmosphere, affecting the satellite's receiving signals.

[0004] In addition to free space loss during signal propagation, atmospheric absorption loss is also an important component of signal attenuation. Atmospheric absorption loss is caused by the absorption and scattering of electromagnetic waves by gas molecules, particles, and water vapor in the atmosphere. In different frequency ranges, the absorption loss of electromagnetic waves varies significantly, especially in the transmission of high-frequency radio waves such as millimeter waves and terahertz bands, where signals will encounter more obvious absorption and attenuation.

[0005] Taking into account that the signal transmission paths from different surface areas to satellites may be subject to different degrees of atmospheric absorption loss, this requires that when calculating the path loss, the meteorological characteristics of different geographical areas and the actual path length differences during signal propagation must be comprehensively considered.

[0006] Atmospheric absorption loss is one of the important factors affecting the quality of satellite communications. Therefore, simplified modeling and accurate calculation of atmospheric absorption loss, especially in interference coexistence environments, are of great engineering significance.

[0007] In the current coexistence of satellite and ground IMT systems, the path loss calculation method based on the free space propagation model and fixed atmospheric absorption loss is usually used. This method only regards the atmospheric absorption loss value as a fixed value, which cannot accurately reflect the loss suffered by the signal during the actual propagation process. Especially in wireless communication systems with different frequency bands such as satellite communications and a large number of ground IMT systems, the traditional fixed atmospheric absorption loss model can no longer meet the needs of modern communication simulation.

[0008] In addition, the existing atmospheric absorption loss models are often based on the assumption that the signal propagation path is transmitted along the zenith (vertical) direction, and based on the traditional atmospheric stratification theory, the meteorological parameters of each layer of the atmosphere are averaged to calculate the propagation loss of each layer of the atmosphere, and finally the propagation loss of each layer of the atmosphere is superimposed to obtain the total atmospheric absorption loss of the satellite-to-ground link. This will make the calculation process extremely slow and occupy a large amount of computing resources when analyzing the propagation loss of large-scale ground communication systems and satellite links.

[0009] The model based on zenith loss also has the problem of only considering the loss of a single frequency band and a specific area of ​​the earth, and does not take into account the differences in atmospheric meteorological parameters at different latitudes of the earth. In the face of increasingly complex interference coexistence scenarios, only analyzing the signal attenuation degree of a single frequency band cannot accurately reflect the variable losses encountered by the signal during actual propagation. Therefore, there is an urgent need for an atmospheric absorption loss estimation covering multiple frequency bands.

[0010] The problems or shortcomings of existing technologies are mainly reflected in the following aspects:

[0011] 1) When calculating atmospheric absorption loss, it is often not considered that in interference coexistence scenarios, different regions on the earth's surface experience different degrees of loss due to different paths and elevation angles through the atmosphere to reach the satellite. This will result in insufficient calculation results and cannot meet the needs of engineering applications.

[0012] 2) When calculating atmospheric absorption loss, the atmospheric layer thickness model is usually considered. The complex layer thickness model will bring a huge computational burden, which is a great limitation, especially when rapid estimation and large-scale data processing are required.

[0013] 3) Furthermore, as the Earth's latitude changes, the atmospheric conditions (such as temperature, humidity, and air pressure) in different latitudes will also vary significantly, and the signal propagation loss will also change accordingly. This change may vary significantly in different latitudes of the Earth.

[0014] Therefore, studying how to build a model that comprehensively considers the atmospheric meteorological differences in different latitudes in order to accurately predict the propagation loss from different regions to satellites is also an issue that current technology urgently needs to solve. Summary of the invention

[0015] Taking into account the problems of low efficiency and high resource consumption in calculating atmospheric absorption loss in specific scenarios, the present invention proposes a simplified calculation method for atmospheric absorption loss based on the ground-to-air interference coexistence scenario, which realizes the simplified calculation of atmospheric absorption loss from large-scale ground systems to satellites in the interference coexistence scenario, and is expected to achieve the goal of balancing calculation accuracy and efficiency in actual engineering applications.

[0016] The simplified calculation method of atmospheric absorption loss in the ground-to-air interference coexistence scenario is specifically described as follows:

[0017] Step 1: Construct a visible area on the earth's surface that interferes with the satellite link, divide the visible area into grids based on longitude and latitude, and determine the center point of each area;

[0018] The visible area on the earth's surface is confirmed based on the input satellite parameters, and the ocean area and uninhabited areas are removed. The remaining visible area is the area that constitutes an interference link to the satellite.

[0019] Step 2: Determine the elevation angle of different areas relative to the satellite based on the positional relationship between the center point of each area and the satellite;

[0020] The calculation formula of elevation angle θ is:

[0021]

[0022] R is the radius of the earth; distance is the distance from the satellite to the center of the grid; h FSS is the vertical height of the satellite relative to the Earth's surface.

[0023] Step 3: Establish three different atmospheric stratification models, medium, low and high, according to latitude, which can cover radio wave signals in the 0-350GHz frequency band.

[0024] For low-latitude regions (0°-22°), the atmospheric stratification includes eight layers; for mid-latitude regions (22°-45°), the atmospheric stratification includes nine layers; for high-latitude regions (45°-90°), the atmospheric stratification includes eight layers.

[0025] Step 4: When the satellite signal passes through different atmospheric stratification models, the actual path length of each atmospheric layer of each model is calculated respectively;

[0026] For each atmospheric layer in different atmospheric stratification models, the actual path length calculation formula is the same:

[0027] l ns (θ) 2 -2Rcos(θ)+R 2 -(R 2 +layers_height(n) 2 =0

[0028] Among them l ns (θ) is the actual path length of the nth atmospheric layer in each atmospheric stratification model, and layers_height(n) is the thickness of the corresponding nth atmospheric layer.

[0029] Step 5: Calculate the absorption loss value of each atmospheric layer when the satellite signal passes through the atmospheric stratification model;

[0030] For different atmospheric stratification models, the calculation formula for the total atmospheric absorption loss is the same:

[0031]

[0032] Among them, A g The atmospheric attenuation ratio γ is calculated by summing the absorption loss values ​​generated by each layer of the atmosphere. n It is a function of the dry air pressure, air temperature, water vapor partial pressure and radio wave frequency of the nth atmospheric layer of the model; N is the total number of layers in each atmospheric stratification model. For the low and high latitude atmospheric stratification model, N is 8; for the mid-latitude atmospheric stratification model, N is 9.

[0033] Step 6: Output the atmospheric absorption loss values ​​in the frequency range of 0-350GHz in different latitudes and elevation areas.

[0034] The advantages of the present invention are:

[0035] 1) The present invention provides a simplified calculation method for atmospheric absorption loss based on the ground-to-air interference coexistence scenario, which can evaluate the atmospheric absorption loss of radio wave signals in the 0-350GHz frequency band. This frequency band covers the current and future major communication frequency bands and has the characteristics of a wide frequency applicability range. The evaluation of this frequency band is not only applicable to the current 5G and future 6G networks, but also has important significance for satellite communications, radars, and high-frequency applications (such as large-scale wireless sensor networks). In addition, by evaluating the atmospheric absorption loss of the ground system at different elevation angles, a more accurate loss calculation method for ground systems in different regions can be effectively provided, thereby supporting the reasonable allocation of system resources in interference coexistence scenarios and optimizing communication performance.

[0036] 2) The present invention provides a simplified calculation method for atmospheric absorption loss based on ground-to-air interference coexistence scenarios, which is suitable for quickly estimating the atmospheric absorption loss of IMT systems-satellites in different ground areas under large-scale interference coexistence scenarios, saving time and computing resources. For complex communication scenarios, especially the joint use between ground IMT systems and satellites, the system needs to consider the impact of atmospheric absorption loss on signal strength. Through an efficient model, the absorption loss in different environments can be quickly calculated to help optimize interference management and spectrum resource allocation. In addition, the present invention can significantly reduce computing resource consumption and can be widely used in real-time network planning and deployment processes.

[0037] 3) The present invention provides a simplified calculation method for atmospheric absorption loss based on the coexistence scenario of ground-to-air interference. An atmospheric stratification model is designed according to the temperature and pressure distribution law of the atmosphere. It can reduce errors when approximating atmospheric absorption losses, and meet the error tolerance allowed by actual engineering applications. Atmospheric absorption losses are affected by factors such as temperature, pressure and humidity. Designing a suitable stratification model can more accurately reflect the impact of changes in these factors on signal propagation. By approximating the atmospheric stratification characteristics (such as atmospheric conditions at different altitudes) through the model, the errors caused by environmental uncertainties can be effectively reduced. This method can not only ensure the accuracy of atmospheric absorption loss prediction, but also ensure that the errors are within a reasonable range in engineering applications, thereby ensuring the robustness and reliability of the communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the interference coexistence scenario of the high-orbit satellite system and the ground large-scale mobile communication system used in the present invention;

[0039] Figure 2 This is a flow chart of a simplified calculation method for atmospheric absorption loss in a ground-to-air interference coexistence scenario according to the present invention;

[0040] Figure 3 It is a schematic diagram of the distribution of temperature relative to geometric height of the present invention;

[0041] Figure 4 It is a schematic diagram of the distribution of pressure relative to geometric height of the present invention;

[0042] Figure 5 This is a simplified calculation comparison diagram of atmospheric absorption loss at different elevation angles and frequencies in low-latitude areas of the present invention. DETAILED DESCRIPTION

[0043] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0044] In order to improve the performance of satellite communication systems, especially in the case of interference coexistence, a simplified calculation method for atmospheric absorption loss in ground-to-air interference coexistence scenarios is proposed. A simplified calculation method for atmospheric absorption loss based on different land areas and different atmospheric conditions has important theoretical significance and application value; specifically, it can not only provide a more accurate reference for the link budget of satellite communication systems, but also help optimize spectrum management and interference suppression strategies, and ensure effective coordination and interference management between different communication systems.

[0045] like Figure 1 As shown in the figure, taking the coexistence of high-orbit satellite systems and ground-based large-scale mobile communication systems as an application scenario, when a single satellite's beam covers a certain area, it will still be interfered by radio wave signals from other ground-based IMT systems in its visible area. First, the visible area of ​​the earth's surface excluding the ocean can be determined based on the satellite's orbital position (generally, the ocean area can be approximately regarded as having no IMT system coverage or the interference to the satellite can be ignored). The visible area is used as the total area set that constitutes an interference link to the satellite. The visible area is gridded with determined longitude and latitude (the default values ​​of 1° longitude and 1° latitude can balance the requirements of calculation accuracy and calculation resource consumption) and the center point of each area is determined. The atmospheric absorption loss value is calculated based on the pitch angle, latitude and distance elements of the point relative to the satellite. The atmospheric absorption loss of the radio wave signals transmitted by the IMT system and other equipment in the grid area can be approximated to the calculated value of the center point of the area. The differences in atmospheric conditions at different latitudes are mainly caused by factors such as the earth's heat distribution, airflow patterns, and climate zones, which affect the physical properties of the atmosphere (such as temperature, pressure, humidity, etc.), which in turn lead to different interference conditions for radio wave signals. Therefore, the scene diagram uses 22° as the dividing line between mid- and low-latitudes, and 45° as the dividing line between mid- and high-latitudes. In this way, the atmospheric absorption loss values ​​in the three different regions of mid-, low-, and high-latitudes are calculated using different atmospheric meteorological elements.

[0046] The simplified calculation method of atmospheric absorption loss based on the ground-to-air interference coexistence scenario is as follows: Figure 2 As shown, the specific steps are as follows:

[0047] Step 1: Construct a visible area on the earth's surface that interferes with the satellite link, divide the visible area into grids based on longitude and latitude, and determine the center point of each area;

[0048] The visible area on the earth's surface is confirmed based on the input satellite parameters, and the ocean area and uninhabited areas are removed. The remaining visible area is the area that constitutes an interference link to the satellite.

[0049] Step 2: Determine the elevation angle of different areas relative to the satellite based on the positional relationship between the center point of each area and the satellite;

[0050] The elevation angle θ is calculated from the relative position of the satellite to the known grid center using the formula:

[0051]

[0052] R is the radius of the earth; distance is the distance from the satellite to the center of the grid, which is calculated by converting the longitude, latitude and altitude elements of the grid area and the satellite into a three-dimensional Cartesian coordinate system, with the center of the earth as the origin; h FSS is the vertical height of the satellite relative to the Earth's surface.

[0053] Step 3: Establish three different atmospheric stratification models (medium, low and high) according to the dimensions, which can cover radio wave signals in the 0-350GHz frequency band.

[0054] The stratification model of the atmosphere is confirmed based on the temperature and pressure distribution law of the annual reference atmosphere. At certain specific altitude layers of the atmosphere at different latitudes, the temperature, pressure and water vapor density are given by corresponding nonlinear functions. The stratification model is determined based on the changing laws of temperature, pressure and water vapor density at middle, low and high latitudes.

[0055] The differences in atmospheric conditions at different latitudes are mainly caused by factors such as the earth's heat distribution, airflow patterns and climate zones, which affect the physical properties of the atmosphere (such as temperature, pressure, humidity, etc.), which in turn leads to different interference conditions for radio wave signals. Therefore, the scene diagram uses 22° as the dividing line between mid- and low-latitudes, and 45° as the dividing line between mid- and high-latitudes, in order to establish three different atmospheric stratifications and calculation models at mid-, low- and high-latitudes.

[0056] For low latitudes (0°-22°), according to Recommendation ITU-R P.835-6, the atmospheric stratification is [0,10], [10,15], [15,17], [17,47], [47,52], [52,72], [72,80], [80,100], with units in kilometers.

[0057] For mid-latitudes (22°-45°), the atmospheric stratification uses [0,10], [10,13], [13,15], [15,17], [17,47], [47,53], [53,72], [72,80], [80,100], with the unit being kilometers.

[0058] For the high latitudes (45°-90°), the atmospheric stratification uses [0,10], [10,15], [15,23], [23,48], [48,53], [53,72], [72,79], and [79,100], with the unit being kilometers.

[0059] Step 4: When the satellite signal passes through different atmospheric stratification models, the actual path length of each atmospheric layer of each model is calculated respectively;

[0060] For each atmospheric layer in different atmospheric stratification models, the actual path length calculation formula is the same:

[0061] l ns (θ) 2 -2Rcos(θ)+R 2 -(R 2 +layers_height(n) 2 =0

[0062] Among them l ns (θ) is the actual path length of the signal through the nth atmospheric layer in each atmospheric stratification model, and layers_height(n) is the thickness of the corresponding nth atmospheric layer.

[0063] For the low- and high-latitude atmospheric stratification models, there are 8 corresponding values ​​of the actual path length; for the mid-latitude atmospheric stratification model, there are 9 corresponding values ​​of the actual path length;

[0064] Step 5: Calculate the absorption loss value of each atmospheric layer when the satellite signal passes through the atmospheric stratification model;

[0065] For each atmospheric layer in different atmospheric stratification models, the absorption loss value calculation formula is the same; for the ground-to-air propagation path, the earth station antenna is the transmitting antenna. Accordingly, the calculation to predict the atmospheric attenuation along this path is:

[0066]

[0067] Among them, A g is the atmospheric absorption loss value of each atmospheric stratification model, N is the total number of layers of each atmospheric stratification model, for the low and high latitude atmospheric stratification model, N is 8; for the mid-latitude atmospheric stratification model, N is 9.

[0068] In the absence of local profiles of temperature, dry air pressure and water vapour partial pressure versus altitude (e.g. from radiosonde measurements), the reference standard atmosphere given in Recommendation ITU-R P.835-6 may be used. ns (θ) is the actual path length of the signal through the nth layer of the atmosphere, which depends on the elevation angle and the thickness of the nth atmosphere, and has the relationship:

[0069]

[0070] Among them, R is the radius of the earth, which is 6371 km, θ is the elevation angle from the center of different grids to the satellite, and h is ns is the thickness of the nth layer after atmospheric stratification. By solving the equation N times, we can obtain l based on the thickness of the nth layer of atmosphere and the elevation angle. ns Value situation.

[0071] Atmospheric specific attenuation coefficient γ n The calculation of depends on the layered model and is a function of the atmospheric temperature, pressure and water vapor density of the nth atmospheric layer of the model; the calculation method is as follows:

[0072] γ=γ o +γ w =0.1820f(N″ oxygen (f)+N″ WaterVapour (f)) (dB / km)

[0073] Among them, γ o and γ w are the specific attenuation (in dB / km) in dry air (nitrogen and non-resonant Debye attenuation caused by air pressure under oxygen conditions) and water vapor conditions; f (in GHz) is the frequency, N″ oxygen (f) and N″ WaterVapour (f) is the imaginary part of the frequency-dependent complex refractive index:

[0074] N″ Oxygen (f) = ∑ i(Oxygen) S i F i +N″ D (f)

[0075] N″ WaterVapour (f) = ∑ i(WaterVapour) S i F i

[0076] S i is the intensity of the ith oxygen or water vapor line, F i It is the shape factor of the oxygen or water vapor spectral line, which is obtained by summing the spectral line data of oxygen attenuation and the spectral line data of water vapor attenuation.

[0077] For oxygen, For water vapor, The water vapor partial pressure e (in hPa) at any altitude can be calculated from the water vapor density ρ (in g / m 3 ) and temperature T (unit K) are calculated using the formula a1, b1 are spectral line coefficients of different frequencies, and p is the dry air pressure (unit: hPa).

[0078] The calculation of the shape factor for oxygen or water vapor spectral lines follows where f i is the frequency of the oxygen or water vapor line, and Δf is the line width: for oxygen, For water vapor Correction factor for oxygen For water vapor the correction factor is 0.

[0079] For the key factors to solve the atmospheric attenuation coefficient: water vapor density, atmospheric temperature and pressure, a layered method will be used for calculation. Usually, the distribution of water vapor in the atmosphere varies greatly, but it can be approximated by the following formula: The elevation h0 = 2 km, and the water vapor density at standard ground level is: ρ0 = 7.5 g / m 3 ;

[0080] For each layer, the integrated mean of the average water vapor density is used to calculate the specific attenuation coefficient of the layer, that is:

[0081]

[0082] The specific attenuation coefficient of each layer is also calculated by the integrated mean of pressure and temperature, that is:

[0083]

[0084] h n is the height of the nth atmospheric layer after stratification.

[0085] Step 6: Output the atmospheric absorption loss values ​​in the frequency range of 0-350GHz in different latitudes and elevation areas.

[0086] Using layered thickness model The calculated atmospheric parameters present complex calculation characteristics (where n is the layer number, δ n is the thickness information of the nth layer), atmospheric absorption loss usually considers atmospheric factors within 0-100km, because the concentration of oxygen and water vapor in the atmosphere significantly affects the propagation of electromagnetic waves within this range. The concentration of oxygen and water vapor above 100km drops sharply, and the absorption effect is weak, and no longer has a significant impact on the propagation path. Generally, the atmosphere of 0-100 kilometers will be refined into 922 layers for layer-by-layer calculation, and the layer height increases exponentially. For large-scale interference coexistence scenarios, there will be extremely high computing resource consumption when analyzing atmospheric absorption losses. Therefore, in order to improve computing efficiency and reduce time consumption in large-scale simulation scenarios, a simplified atmospheric stratification model will be established based on the distribution function of pressure and humidity relative to atmospheric height. For example Figure 3 and Figure 4 As shown, the curve of temperature relative to geometric height distribution can be simplified as N segments of linear change lines with different slopes, and the pressure and geometric height changes can also be approximately regarded as an approximately linear straight line. The characteristics of the curves of atmospheric temperature and pressure relative to geometric height distribution change with different latitudes. Therefore, the stratified model that divides the atmosphere into N layers according to middle, low and high latitudes can be used to confirm the temperature, pressure, water vapor density and other information of each atmospheric layer, thereby simplifying the model.

[0087] In order to accurately calculate the atmospheric transmission absorption attenuation, it is necessary to obtain the relevant air pressure, water vapor density, and temperature parameters along the propagation path. Since it is very difficult to implement atmospheric observations, the measured data have problems such as a small vertical expansion height range and uneven distribution of data at different heights. Therefore, the global annual average reference atmospheric parameters for different latitudes given in "ITU-R P.835-6 Recommendation" are used as the calculation standard.

[0088] The stratification model of the atmosphere is confirmed based on the temperature and pressure distribution law of the annual reference atmosphere. At certain specific altitude layers of the atmosphere at different latitudes, the temperature, pressure and water vapor density are given by corresponding nonlinear functions. The stratification model is determined based on the variation law of temperature, pressure and water vapor density at mid-, low- and high-latitudes. The specific attenuation coefficient of each layer is also calculated by the integrated mean of pressure and temperature, that is,

[0089] like Figure 5 As shown in the figure, it is a test diagram of the theoretical results of the simplified calculation of atmospheric absorption loss. This figure is a schematic diagram of the comparison of atmospheric absorption loss values ​​under different elevation angles in low-latitude areas. The horizontal axis is the radio wave frequency in GHz, and the vertical axis is the simplified calculated value of atmospheric absorption loss in dB. It can be seen from the figure that the atmospheric absorption loss value under the 90° elevation angle is lower than that under the 30° and 60° conditions. The reason is that the larger the elevation angle, the shorter the actual path length of the ground system relative to the satellite, and the smaller the absorption loss value. In addition, the curve change value has a significant nonlinear characteristic. In the frequency band below 10GHz, the value of atmospheric absorption loss is small. The reason is that the size of oxygen and water vapor molecules is much smaller than the wavelength of low-frequency radio waves (the molecular scale is in the nanometer or smaller range). When the size of the molecule is much smaller than the wavelength, it is difficult for the molecule to significantly absorb the energy of the radio wave, resulting in a smaller absorption loss. As the frequency increases, the atmospheric absorption loss of radio wave signals increases, mainly because the interaction between high-frequency radio waves and gas molecules in the atmosphere (such as oxygen and water vapor) becomes more significant, and in some frequency bands, they are significantly affected by atmospheric absorption, mainly because gas molecules in the atmosphere (such as water vapor and oxygen) resonate and absorb electromagnetic waves of specific frequencies. The following are several major absorption frequency bands and their causes:

[0090] Around 1.22GHz (water vapor absorption), the frequency range is about 20GHz to 25GHz. The main reason is that in this frequency band, water vapor molecules in the atmosphere will resonate with radio waves and absorb a lot of energy, resulting in significant signal attenuation. It is suitable for short-distance communication, and the signal attenuation is serious for long-distance communication. This feature is also used to measure the water vapor content in the atmosphere (such as meteorological observation).

[0091] Around 2.60 GHz (oxygen absorption), the frequency range is about 57 GHz to 64 GHz. The main reason is that in this frequency band, the oxygen molecules in the atmosphere will strongly resonate and absorb the radio waves, resulting in extremely high signal attenuation. In this frequency band, the signal can hardly propagate more than 1 km, so it is suitable for small-range wireless communications (such as millimeter wave communications).

[0092] Around 3.118 GHz: Another absorption peak of oxygen, the absorption is stronger, but not as obvious as 60 GHz.

[0093] Around 4.183GHz (strong water vapor absorption), frequency range: about 180GHz to 200GHz. The main reason is that water vapor has another significant resonance absorption peak in this frequency band, and the signal is seriously absorbed and lost in this frequency band. There are few communication applications in this frequency band, mainly for meteorological remote sensing and scientific research.

[0094] Around 5.325 GHz: Another absorption peak of water vapor, with significant absorption loss.

Claims

1. A simplified calculation method for atmospheric absorption loss based on the coexistence scenario of ground-to-air interference, characterized in that: The specific steps are as follows: Step 1: Construct a visible area on the earth's surface that interferes with the satellite link, divide the visible area into grids based on longitude and latitude, and determine the center point of each area; Step 2: Determine the elevation angle of different areas relative to the satellite based on the positional relationship between the center point of each area and the satellite; The calculation formula of elevation angle θ is: R is the radius of the earth; distance is the distance from the satellite to the center of the grid; h FSS is the vertical height of the satellite relative to the Earth’s surface; Step 3: Establish three different atmospheric stratification models, namely, medium, low and high, according to latitude, which can cover radio wave signals in the 0-350GHz frequency band; For low latitudes, the atmospheric stratification includes eight layers; for mid-latitudes, the atmospheric stratification includes nine layers; for high latitudes, the atmospheric stratification includes eight layers; Step 4: When the satellite signal passes through different atmospheric stratification models, the actual path length of each atmospheric layer of each model is calculated respectively; For each atmospheric layer in different atmospheric stratification models, the actual path length calculation formula is the same: l ns (i) 2 -2Rcos(θ)+R 2 -(R 2 +layers_height(n)) 2 =0 Among them l ns (θ) is the actual path length of the nth atmospheric layer in each atmospheric layering model, and layers_height(n) is the thickness of the corresponding nth atmospheric layer; Step 5: Calculate the absorption loss value of each atmospheric layer when the satellite signal passes through the atmospheric stratification model; For different atmospheric stratification models, the calculation formula for the total atmospheric absorption loss is the same: Among them, A g The atmospheric attenuation ratio γ is calculated by summing the absorption loss values ​​generated by each layer of the atmosphere. n It is a function of the dry air pressure, air temperature, water vapor partial pressure and radio wave frequency of the nth atmospheric layer of the model; N is the total number of layers in each atmospheric layer model; Step 6: Output the atmospheric absorption loss values ​​in the frequency range of 0-350GHz in different latitudes and elevation areas.

2. A simplified calculation method for atmospheric absorption loss based on a ground-to-air interference coexistence scenario according to claim 1, characterized in that: In the step 1, the visible area on the earth's surface is confirmed according to the input satellite parameters, and the ocean part and the uninhabited area are removed. The remaining visible area is the area that constitutes an interference link to the satellite.

3. The simplified calculation method for atmospheric absorption loss based on the ground-to-air interference coexistence scenario according to claim 1, characterized in that: In the step 1, when the visible area is divided into grids, the visible area is divided into 1 longitude and 1 latitude.

4. The simplified calculation method for atmospheric absorption loss based on the ground-to-air interference coexistence scenario according to claim 1, characterized in that: In the step 2, the elevation angle θ from the grid center to the satellite is used as the elevation angle value for evaluating the atmospheric absorption loss in this area.

5. The simplified calculation method for atmospheric absorption loss based on the ground-to-air interference coexistence scenario according to claim 1, characterized in that: In the step three, the stratification model of the atmosphere is confirmed based on the temperature and pressure distribution law of the annual reference atmosphere. At certain specific altitude layers of the atmosphere at different latitudes, the temperature, pressure and water vapor density are given by corresponding nonlinear functions. The stratification model is determined based on the temperature, pressure and water vapor density variation laws at mid-, low- and high-latitudes.

6. The simplified calculation method for atmospheric absorption loss in a ground-to-air interference coexistence scenario according to claim 1, characterized in that: In the step three, 22° is used as the dividing line between mid- and low-latitudes, and 45° is used as the dividing line between mid- and high-latitudes, thereby establishing three different atmospheric stratification models at mid-, low-, and high-latitudes.

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