Satellite cooperation method based on satellite cluster

Abstract

This invention discloses a satellite collaboration method based on satellite constellations. This method determines the visible elevation angle of satellites by observing the real-time distribution of low Earth orbit satellites and combining this with the location information of ground terminals. Based on the visible elevation angle, the visible satellite range of the ground terminal is determined. Within the visible satellite range, the satellite constellation range is determined based on the constellation polar angle. Based on satellite density and area, and considering usage requirements, the N closest satellites to the ground terminal in the constellation are selected to collaborate, while the remaining satellites in the constellation actively enter a silent state to avoid signal interference. This mechanism of selecting the N closest nodes and collaborative silence significantly improves the coverage of the satellite network to ground targets compared to traditional satellite collaboration modes, reduces unnecessary signal transmission and potential mutual interference, enhances the anti-interference capability of the satellite constellation, and strengthens the stability and reliability of the satellite communication system.

Description

Technical Field

[0001] This invention relates to the field of satellite communication cooperation systems, and in particular to a satellite cooperation method based on satellite clusters. Background Technology

[0002] Satellite communication technology, with its wide-area coverage and low-Earth orbit constellation advantages, can provide high-speed, low-latency broadband connectivity services to remote areas, ocean areas, and aviation zones that are difficult to cover by traditional terrestrial networks. It can also support emergency communication support, IoT terminal interconnection, and rapid deployment of digital infrastructure.

[0003] In recent years, many companies have been actively deploying large-scale low Earth orbit satellite constellations. However, increasing the number of satellite launches does not necessarily lead to increased throughput. The launch of a large number of satellites can cause severe inter-satellite interference, resulting in a decline in system performance. To address this interference challenge, researchers have proposed the concept of satellite collaboration, using satellite swarms as a key means to effectively manage satellite communication systems and mitigate the impact of inter-satellite interference. A satellite swarm is a distributed system composed of a group of satellites working collaboratively. These satellites can communicate with each other and share data, enhancing the anti-interference capability of the satellite communication system.

[0004] Traditional satellite cooperation methods involve having all visible satellites or randomly / fixed satellites participate in the service. This approach can easily lead to low utilization of satellite resources and can also cause severe signal interference within the cluster, resulting in low system coverage and insufficient anti-interference capabilities. Summary of the Invention

[0005] To address the shortcomings of existing methods, this invention provides a satellite collaboration method based on satellite constellations, comprising:

[0006] 1. Observe the real-time distribution of low Earth orbit satellites, and determine the visible elevation angle of the satellites and the shortest distance D from the ground terminal to the visible satellites by combining the location information of the ground terminal. min The longest distance D from a ground terminal to a visible satellite is the satellite's orbital altitude minus the Earth's radius. max for:

[0007]

[0008] Based on D min and D max The visible satellite range of the ground terminal is calculated using the following formula.

[0009]

[0010] Where R is the Earth's radius, R sat Let θ be the radius of the satellite's orbital sphere. visThis is the visible elevation angle for the satellite.

[0011] 2. Determine the cluster polar angle φ with the Earth's center as the center within the visible satellite range. clu The maximum distance D from the ground terminal to the satellite constellation is calculated based on the visible elevation angle of the satellites. clu :

[0012]

[0013] Use the following formula to calculate the satellite constellation range.

[0014]

[0015] 3. To calculate the distance from each satellite in the satellite constellation to the ground terminal, first convert the satellite's spherical coordinates to Cartesian coordinates using the following formula:

[0016] x i =R sat sinθ i cosφ i ,y i =R sat sinθ i sinφ i ,z i =R sat cosθ i ;

[0017] Next, the spherical coordinates of the ground terminal are converted to Cartesian coordinates using the following formula:

[0018] x g =R cosφ g cosθ g ,y g =R cosφ g sinθ g ,z g =Rsinφ g ,

[0019] Where, θ i and φ i φ represents the polar angle and azimuth angle of the satellite. g and θ g Given the latitude and longitude of the ground terminal, the Cartesian coordinates of the satellite are (x... i ,y i ,z i The coordinates of the ground terminal are (x... g ,y g ,z g );

[0020] Finally, the straight-line distance from each satellite to the ground terminal is calculated using the Euclidean distance formula, and the distance d is obtained. i for:

[0021]

[0022] For all distances d i The satellites are sorted in ascending order. Based on satellite density and area, and combined with usage requirements, the satellites that are N closest to the ground terminal in the satellite cluster are selected to work together, while the remaining satellites in the cluster actively enter a silent state.

[0023] This invention discloses a satellite collaboration method based on satellite clusters. Compared with the prior art, the core advantage of this invention is that, based on satellite density and area, and combined with usage requirements, the satellites that are N closest to the ground terminal in the satellite cluster are selected to work together, while the remaining satellites in the cluster actively enter a silent state. This method significantly improves satellite resource utilization and system coverage by reducing unnecessary signal transmission and potential mutual interference, and enhances the anti-interference capability of the communication system. Attached Figure Description

[0024] Figure 1 A flowchart of a satellite collaboration method based on satellite constellations provided by the present invention.

[0025] Figure 2 This is a schematic diagram of the satellite cluster system architecture designed for this invention.

[0026] Figure 3 These are the results of a simulation experiment. Detailed Implementation

[0027] The core of this invention is to provide a satellite collaboration method based on satellite clusters, which can improve satellite resource utilization and system coverage, and enhance the anti-interference capability of satellite communication systems.

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 This is a flowchart illustrating the method of the present invention. The satellite collaboration method based on satellite constellations provided by the present invention specifically includes the following steps:

[0030] Step 1: Spatial distribution modeling, as shown in the instruction manual. Figure 2 The model uses a binomial point process (BPP) to model the distribution of low Earth orbit (LEO) satellites, determining the visible elevation angle of the satellites with the ground terminal as the center and the cluster polar angle with the Earth's center as the center.

[0031] Step 2: Observe the real-time distribution of low Earth orbit satellites, and determine the visible elevation angle of the satellites and the shortest distance D from the ground terminal to the visible satellites by combining the location information of the ground terminal. min Subtract the Earth's radius from the satellite's orbital altitude, and calculate the longest distance D from the ground terminal to the visible satellite using formula (1) based on the visible elevation angle. max Combined with D min and D max Use formula (2) to determine the visible satellite range of the ground terminal.

[0032]

[0033] Where R is the Earth's radius, R sat Let θ be the radius of the satellite's orbital sphere. vis This is the visible elevation angle for the satellite.

[0034] Step 3: Within the visible satellite range, based on the cluster polar angle φ clu Use formula (3) to calculate the maximum distance from the ground terminal to the satellite cluster, and use formula (4) to determine the range of the satellite cluster;

[0035]

[0036] Step 4: Calculate the distance from each satellite in the satellite constellation to the ground terminal. First, use formula (5) to convert the satellite spherical coordinates to Cartesian coordinates:

[0037] x i =R sat sinθ i cosφ i ,y i =R sat sinθ i sinφ i ,z i =R sat cosθ i (5)

[0038] Next, use formula (6) to convert the spherical coordinates of the ground terminal to Cartesian coordinates:

[0039] x g =R cosφ g cosθ g ,y g =R cosφ g sinθ g ,z g =Rsinφ g (6)

[0040] Where, θ i and φi φ represents the polar angle and azimuth angle of the satellite. g and θ g Given the latitude and longitude of the ground terminal, the Cartesian coordinates of the satellite are (x... i ,y i ,z i The coordinates of the ground terminal are (x... g ,y g ,z g );

[0041] Finally, the straight-line distance from each satellite to the ground terminal is calculated using the Euclidean distance formula, and the distance d is obtained. i for:

[0042]

[0043] For all distances d i The satellites are sorted in ascending order. Based on satellite density and area, and combined with usage requirements, the satellites that are N closest to the ground terminal in the satellite cluster are selected to work together, while the remaining satellites in the cluster actively enter a silent state.

[0044] Step 5: Simulation Experiment. Building upon steps 1 to 4, a satellite antenna gain model and a channel model are further constructed to analyze the system coverage of the proposed satellite cluster-based cooperative method. System coverage is a key indicator for measuring the quality of service of a wireless communication system, defined as the probability that the signal-to-interference ratio (SIR) of a ground terminal is not lower than a specific threshold. Simulation experiments verify the effectiveness of this cooperative method in improving system coverage.

[0045] Create a satellite antenna gain model, where G n The total gain from satellite n to the ground terminal. For the transmit antenna gain of the satellites within the cluster, For the transmit antenna gain of visible but not cluster-in-the-cluster satellites, G r For the user's receiving antenna gain, f c denoted as carrier frequency, and c as the speed of light.

[0046]

[0047] Channel modeling employs a composite channel fading model, combining large-scale path loss and small-scale multipath fading. Large-scale fading is addressed through the model ||x n -y1|| -γ The signal attenuation characteristics are described by distance, where γ is the path loss exponent, and x... ny1 represents the position of the nth satellite, and y2 represents the position of the ground terminal. Small-scale fading is modeled using the Nakagami-m distribution, with its probability density function being Equation (9). The parameter m controls the fading intensity. When m = 1, it degenerates into Rayleigh fading, which is suitable for non-line-of-sight (LoS) scenarios. When m > 1, it is closer to LoS ​​scenarios and is suitable for the high-altitude characteristics of satellite communication. This model takes into account both mathematical solvability and actual channel characteristics, and is suitable for analyzing the coverage performance under joint transmission of satellite constellations.

[0048]

[0049] The ratio of useful signal power to interfering signal power (SIR) of the system is calculated using formula (11). The numerator represents the summation of the power of satellites located within the cluster that are N closest to the ground terminal, and the denominator represents the summation of the power of interfering satellites located in the visible area but not within the cluster area. Where Φ sat This represents all satellites, where P is the satellite's transmission power and H is the satellite's transmission power. n This represents the small-scale fading from satellite n to the user. Taking the three most recent satellites as an example, coverage was verified using MATLAB simulation. The simulation parameters are shown in Table 1. Through Monte Carlo simulation, the system coverage was compared in the following four scenarios:

[0050] Cluster silence: Select the three satellites in the satellite cluster that are closest to the ground terminal to work together, and the remaining satellites in the cluster actively enter a silent state;

[0051] Cluster non-silent: Select the three satellites in the satellite cluster that are closest to the ground terminal to work together, and the remaining satellites in the cluster are non-silent, which are considered interference satellites;

[0052] Single satellite and cluster silence: Select the satellite closest to the ground terminal in the satellite cluster to work, and the other satellites in the cluster actively enter a silent state;

[0053] No cooperation: Only the satellite closest to the ground terminal in the satellite cluster is active, and the other satellites in the cluster are not silent and are considered interference satellites.

[0054]

[0055] Table 1 Simulation Parameters

[0056]

[0057] Simulation results are shown in the attached manual. Figure 3 As shown, the coverage of the cluster silent scheme is higher than that of the other three cases at different SIR thresholds, proving that the satellite cooperation method proposed in this invention can significantly improve the coverage of satellite networks to ground targets, enhance the anti-interference capability of satellite clusters, and strengthen the stability and reliability of satellite communication systems.

Claims

1. A satellite collaboration method based on satellite constellations, characterized in that, Includes the following steps: S1 observes the real-time distribution of low Earth orbit satellites, combines this with the location information from ground terminals to determine the visible elevation angle of the satellites, and then determines the visible satellite range of the ground terminals based on the visible elevation angle. The shortest distance D from the ground terminal to the visible satellite min The longest distance D from a ground terminal to a visible satellite is the satellite's orbital altitude minus the Earth's radius. max for: Based on D min and D max The visible satellite range of the ground terminal is calculated using the following formula. : Where R is the Earth's radius, R sat Let θ be the radius of the satellite's orbital sphere. vis The visible elevation angle of the satellite; S2 determines the cluster polar angle with the Earth's center as the center within the visible satellite range, and calculates the maximum distance from the ground terminal to the satellite cluster based on the cluster polar angle: Use the following formula to calculate the satellite constellation range: Where, φ clu D is the cluster polar angle. clu This represents the maximum distance from the ground terminal to the satellite constellation. For the satellite constellation range; S3 calculates the distance from each satellite in the satellite constellation to the ground terminal. Based on satellite density and area, and combined with usage requirements, it selects the N satellites in the constellation that are closest to the ground terminal to work together, while the remaining satellites in the constellation actively enter a silent state.

2. The satellite collaboration method based on satellite constellations as described in claim 1, characterized in that, Step S3 involves selecting the satellites N closest to the ground terminal in the satellite cluster to work collaboratively while the remaining satellites enter a silent state: First, convert the satellite spherical coordinates to Cartesian coordinates using the following formula: x i =R sat sinθ i cosφ i ,y i =R sat sinθ i sinφ i ,z i =R sat cosθ i ; Next, the spherical coordinates of the ground terminal are converted to Cartesian coordinates using the following formula: x g =Rcosφ g cosθ g ,y g =R cosφ g sinθ g ,z g =Rsinφ g , Where, θ i and φ i φ represents the polar angle and azimuth angle of the satellite. g and θ g Given the latitude and longitude of the ground terminal, the Cartesian coordinates of the satellite are (x... i ,y i ,z i The coordinates of the ground terminal are (x... g ,y g ,z g ); Finally, based on the coordinates of the satellite and the ground terminal, the straight-line distance from each satellite to the ground terminal is calculated using the Euclidean distance formula, and the distance d is then calculated. i for: For all distances d i The satellites are sorted in ascending order. Based on satellite density and area, and combined with usage requirements, the satellites that are N closest to the ground terminal in the satellite cluster are selected to work together, while the remaining satellites in the cluster actively enter a silent state.

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