A downlink interference analysis method based on virtual probability satellite

Abstract

This invention belongs to the field of satellite communication technology and discloses a downlink interference analysis method based on virtual probabilistic satellites. The method includes: modeling the satellite distribution using a Poisson point process distribution based on the satellite distribution spatial density to obtain a satellite distribution model; deriving the probability density function of the satellite distribution with elevation angle within a certain range, so that the downlink lumped interference is only related to the satellite distribution density, distribution range, and transmission parameters, and is independent of the exact position and number of satellites; and analyzing the interference signal at the ground receiver. This application shows good fitting performance for constellations with different numbers of satellites and can effectively reduce the computational complexity in long-term analysis, enabling efficient interference analysis and calculation.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication technology, specifically relating to a downlink interference analysis method based on virtual probabilistic satellites. Background Technology

[0002] Low Earth Orbit (LEO) satellites have garnered widespread attention due to their advantages such as low latency and low propagation loss. With the maturation of microsatellite mass production technology and the rapid development of reusable launch vehicles and multi-satellite launch technologies, a new wave of LEO satellite constellation construction has swept the globe. However, this explosive growth in constellations, coupled with the severe shortage of spectrum and orbital resources, has brought unprecedented challenges to interference management.

[0003] Various research methods have been developed for analyzing interference between low-Earth orbit (LEO) constellations. Existing techniques employ deploying reference satellites in the target area to generate constellation snapshots, using the probability of these reference satellites' appearance as weights to calculate the equivalent power flux density (EPFD) under each snapshot, and summarizing their probability distribution to assess the interference of non-geostationary orbit (NGSO) systems on GSO systems. Existing techniques also propose a "double-precision" spatial position probability analysis method: dividing the ground latitude and longitude into coarse and fine grids, and sampling within the grids to complete interference calculations and characteristic statistics. Furthermore, existing techniques start with constellation configuration and ground station field-of-view satellite distribution, using a ground-end interference-to-noise ratio (INR) protection threshold to establish a probability assessment framework, revealing the probability distribution characteristics of harmful interference between systems.

[0004] With the increasing payload capacity of satellite platforms and the growing demands for communication capacity and quality of service, the number of satellites has surged, leading to significantly finer granularity in system resource scheduling and control. This has exacerbated the coupling between internal and external interference within the constellation, placing higher demands on the accuracy and efficiency of interference assessment methods. Unlike geostationary orbit (GSO) systems, low-Earth orbit (LEO) constellations have a large number of satellites, constantly changing positions and beam pointing, and earth stations often connect to multiple satellites. Coupled with the rapid development of terrestrial wireless communication, this results in a massive workload for interference calculations. The time-varying relative positions between satellites and ground stations make the spatial geometry highly dynamic, further increasing the complexity of interference calculations. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this application provides a downlink interference analysis method based on virtual probabilistic satellites. Starting from the mechanism of co-channel interference, a three-dimensional distribution modeling method for low-Earth orbit constellations is introduced to perform equivalent modeling of the satellite distribution in the airspace. This makes the regionalized downlink lumped interference only related to the satellite distribution density, distribution range, and launch parameters, and independent of the exact location and number of satellites. This reduces the computational complexity of interference and effectively shortens the analysis time, thereby achieving efficient calculation of downlink lumped interference from low-Earth orbit satellites.

[0006] To achieve the above objectives, this application employs the following technical solution:

[0007] This application discloses a downlink interference analysis method based on virtual probabilistic satellites, comprising the following steps:

[0008] Step 1: Based on satellite distribution spatial density A satellite distribution model was obtained by using a three-dimensional distribution modeling method for low-Earth orbit constellations.

[0009] Step 2: Based on the satellite distribution model obtained in Step 1, derive the satellite distribution according to elevation angle. probability density function of the distribution ;

[0010] Step 3: Calculate the total satellite interference power received at the ground receiver using the link calculation.

[0011] Step 4: Calculate the downlink interference analysis index results based on virtual probabilistic satellites using the lumped interference power received by the ground station.

[0012] A further improvement to this application is that step 1 specifically includes the following steps:

[0013] Step 1.1: The low-orbit satellite downlink interference scenario is set as follows: satellite transmit power is... Communication is conducted using the ITU-R S.1428 antenna pattern, with the communication direction perpendicular to the ground station.

[0014] Step 1.2: Assume the ground is directly below the spherical cap, with the lowest elevation angle being... Satellites with potential interference are in half-angle. The spherical cap follows a three-dimensional distribution modeling method that conforms to a low-orbit constellation, and the solid angular area corresponding to the spherical cap is... for:

[0015] ;

[0016] in, It is the azimuth angle. As variables, ;

[0017] The number of interference source satellites within the visible spherical cap of the ground station Obtain the parameter as A method for modeling the three-dimensional distribution of low-orbit constellations;

[0018] Step 1.3: Assume that the number of interfering satellites on the spherical cap is... ,but The satellite distribution model is as follows:

[0019] ;

[0020] in, This represents the actual number of satellites. The natural base, This is the expected value.

[0021] A further improvement in this application is that step 2 specifically includes the following steps:

[0022] Step 2.1, given... The satellites containing interference sources are independently and identically distributed on the spherical cap and fall uniformly over an area element. Above, area yuan Represented as:

[0023] ;

[0024] in, The pitch angle, The azimuth angle is and the radius of the sphere is . , For the Earth's radius, The altitude of the satellite's orbit;

[0025] Step 2.2, set the radius of the sphere. Normalization yields solid angle infinitesimal elements , represented as:

[0026] ;

[0027] Solid angle element on a sphere The area is ;

[0028] Step 2.3: After normalization, the pitch angle probability density function for

[0029] ;

[0030] in, .

[0031] A further improvement in this application is that step 3, calculating the lumped interference power received by the ground receiver, specifically includes the following steps:

[0032] Step 3.1: In the scenario of downlink disturbance in a low-Earth orbit satellite system, calculate the elevation angle as follows: The power of the interference signal generated by the satellite to the ground station:

[0033] ;

[0034] in, For the first Each satellite's launch power, The satellite's signal frequency. Antenna directional gain, For the ground station receiving antenna gain, Indicates link distance;

[0035] Step 3.2: Utilize the lowest elevation angle of the ground station Interference signal power caused by internal interference sources Calculate the lumped interference power received by the ground station. :

[0036] ;

[0037] in, The number of interfering satellites, This indicates the operation of obtaining the desired result. For the first One interference source satellite.

[0038] A further improvement in this application is that the results of the downlink interference analysis in step 4, i.e., the calculation of the drying ratio, are... :

[0039] ;

[0040] in, To construct the noise power using the equivalent noise temperature, Boltzmann's constant, Equivalent noise temperature For bandwidth.

[0041] A further improvement in this application is that the ground receiver antenna model adopts ITU-R S.1528-0.

[0042] The beneficial effects of this application are as follows: Starting from the mechanism of co-channel interference, this application treats potential interfering satellites within the visible range as randomly distributed spatial points within a spherical cap region for downlink interference. Combining the free-space propagation model and the antenna directional gain function, an analytical expression for the relationship between the interference power of a single satellite and its elevation angle is constructed. Furthermore, the expected value of the total interference power is solved by integration, thereby achieving equivalent modeling and efficient calculation of the interference scenario. Traditional snapshot-based interference calculation models require determining the specific spatial position, satellite-to-ground distance, incident azimuth angle, and elevation angle of all satellites within the visible range at each analysis moment, and recalculating the directional gain of the transmitting and receiving antennas accordingly. This requires a large amount of computation and time, and is extremely complex. The introduction of a three-dimensional distribution modeling method for low-Earth orbit constellations allows for equivalent modeling of the satellite distribution in the airspace. This ensures that the regionalized downlink lumped interference is only related to the satellite distribution density, distribution range, and transmission parameters, and is independent of the exact position and number of satellites. This reduces the complexity of interference calculation and effectively shortens the analysis time. Attached Figure Description

[0043] Figure 1 This is a flowchart of the application process.

[0044] Figure 2 A schematic diagram of the satellite distribution modeling scenario for this application.

[0045] Figure 3 This describes the absolute error of the interference power implemented in this application.

[0046] Figure 4 This describes the relative error of the interference power implemented in this application. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be used to limit the scope of protection of the present invention.

[0048] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0049] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] like Figure 1-2 As shown, this application discloses a downlink interference analysis method based on virtual probabilistic satellites, which specifically includes the following steps:

[0051] Step 1: Based on satellite distribution spatial density A low-Earth orbit (LEO) constellation 3D distribution modeling method is used to obtain a satellite distribution model. The specific steps involved in this modeling process are as follows:

[0052] Step 1.1: The low-orbit satellite downlink interference scenario is set as follows: satellite transmit power is... Communication is conducted using the ITU-R S.1428 antenna pattern, with the communication direction perpendicular to the ground station.

[0053] Step 1.2: Assume the ground is directly below the spherical cap, with the lowest elevation angle being... Satellites with potential interference are in half-angle. The spherical cap follows a three-dimensional distribution modeling method that conforms to a low-orbit constellation, and the solid angular area corresponding to the spherical cap is... for:

[0054] ;

[0055] in, It is the azimuth angle. As variables, ;

[0056] The number of interference source satellites within the visible spherical cap of the ground station Obtain the parameter as A method for modeling the three-dimensional distribution of low-orbit constellations;

[0057] Step 1.3: Assume that the number of interfering satellites on the spherical cap is... ,but The satellite distribution model is as follows:

[0058] ;

[0059] in, This represents the actual number of satellites. The natural base, This is the expected value.

[0060] Step 2: Based on the satellite distribution model obtained in Step 1, derive the satellite distribution according to elevation angle. probability density function of the distribution Specifically, it includes the following steps:

[0061] Step 2.1, given... The satellites containing interference sources are independently and identically distributed on the spherical cap and fall uniformly over an area element. Above, area yuan Represented as:

[0062] ;

[0063] in, The pitch angle, The azimuth angle is and the radius of the sphere is . , For the Earth's radius, The altitude of the satellite's orbit;

[0064] Step 2.2, set the radius of the sphere. Normalization yields solid angle infinitesimal elements , represented as:

[0065] ;

[0066] Solid angle element on a sphere The area is ;

[0067] Step 2.3: After normalization, the pitch angle probability density function for

[0068] ;

[0069] in, .

[0070] Step 3: Calculate the total satellite interference power received at the ground receiver using the link calculation method. This includes the following steps:

[0071] Step 3.1: In the scenario of downlink disturbance in a low-Earth orbit satellite system, calculate the elevation angle as follows: The power of the interference signal generated by the satellite to the ground station:

[0072] ;

[0073] in, For the first Each satellite's launch power, The satellite's signal frequency. Antenna directional gain, For the ground station receiving antenna gain, Indicates link distance;

[0074] Step 3.2: Utilize the lowest elevation angle of the ground station Interference signal power caused by internal interference sources Calculate the lumped interference power received by the ground station. :

[0075] ;

[0076] in, The number of interfering satellites, This indicates the operation of obtaining the desired result. For the first One interference source satellite.

[0077] Step 4: Calculate the downlink interference analysis index based on virtual probabilistic satellites using the lumped interference power received by the ground station, i.e., calculate the dryness ratio. :

[0078] ;

[0079] in, To construct the noise power using the equivalent noise temperature, Boltzmann's constant, Equivalent noise temperature For bandwidth.

[0080] To verify this application, simulation parameters were set, assuming the satellites are distributed in orbits at an altitude of 500 km, the transmit power is 1 dBW, the transmit antenna aperture is 0.6 m, the operating frequency is 1.67 GHz, the signal bandwidth is 20 kHz, and the system equivalent noise temperature is 550 K. The absolute error variation curves of the interference power calculation results and the traditional summation interference power calculation results obtained using the above steps are shown below. Figure 3 As shown, the relative error is as follows Figure 4 As shown.

[0081] Depend on Figures 3-4As can be seen, the interference power calculated in this application has a very small error compared to traditional methods, with a maximum absolute error of less than 0.46 dB and a maximum relative error of no more than 2.8%. Statistical analysis of the two methods shows that the traditional interference link analysis method takes approximately 836.11 seconds, while the equivalent calculation method based on the probabilistic statistical model takes approximately 278.71 seconds. Therefore, it can be concluded that the equivalent calculation method in this application effectively reduces the analysis time compared to the traditional interference power calculation method, and the calculation results are not significantly different.

[0082] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A downlink interference analysis method based on virtual probabilistic satellites, characterized in that: The downlink interference analysis method specifically includes the following steps: Step 1: Based on satellite distribution spatial density A satellite distribution model was obtained by using a three-dimensional distribution modeling method for low-Earth orbit constellations. Step 2: Based on the satellite distribution model obtained in Step 1, derive the satellite distribution according to elevation angle. probability density function of the distribution ; Step 3: Calculate the total satellite interference power received by the ground receiver using the link; Step 4: Calculate the downlink interference analysis index results based on virtual probabilistic satellites using the lumped interference power received by the ground station. Step 2 specifically includes the following steps: Step 2.1, given... The satellites containing interference sources are independently and identically distributed on the spherical cap and fall uniformly over an area element. Above, area yuan Represented as: ； in, The pitch angle, The azimuth angle is and the radius of the sphere is . , For the Earth's radius, The altitude of the satellite's orbit; Step 2.2, set the radius of the sphere. Normalization yields solid angle infinitesimal elements Then the solid angle infinitesimal element The area of ​​the corresponding sphere is Among them, solid angle micro-element The calculation is as follows: ； Step 2.3: After normalization, the pitch angle probability density function for ； in, ; Step 3, calculating the lumped interference power received by the ground receiver, specifically includes the following steps: Step 3.1: In the scenario of downlink disturbance in a low-Earth orbit satellite system, calculate the elevation angle as follows: The power of the interference signal generated by the satellite to the ground station: ； in, For the Each satellite's launch power, The satellite's signal frequency. Antenna directional gain, For the ground station receiving antenna gain, Indicates link distance; Step 3.2: Utilize the lowest elevation angle of the ground station Interference signal power caused by internal interference sources Calculate the lumped interference power received by the ground station. : ； in, The number of interfering satellites, This indicates the operation of obtaining the desired result. For the One interference source satellite; In step 4, the results of the downlink interference analysis are used to calculate the drying ratio. : ； in, To construct the noise power using the equivalent noise temperature, Boltzmann's constant, Equivalent noise temperature For bandwidth.

2. The downlink interference analysis method based on virtual probabilistic satellites according to claim 1, characterized in that: Step 1 specifically includes the following steps: Step 1.1: The low-orbit satellite downlink interference scenario is set as follows: satellite transmit power is... Communication is conducted using the ITU-R S.1428 antenna pattern, with the communication direction perpendicular to the ground station. Step 1.2: Assume the ground is directly below the spherical cap, with the lowest elevation angle being... Satellites with potential interference are in half-angle. The spherical cap follows a three-dimensional distribution modeling method that conforms to a low-orbit constellation, and the solid angular area corresponding to the spherical cap is... for: ； in, It is the azimuth angle. As variables, ; The number of interference source satellites within the visible spherical cap of the ground station Obtain the parameter as A method for modeling the three-dimensional distribution of low-orbit constellations; Step 1.3: Assume that the number of interfering satellites on the spherical cap is... ,but The satellite distribution model is as follows: ； in, This represents the actual number of satellites. The base is the natural number. This is the expected value.

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