Calculation And Analysis Of Coverage Performance Of Leo Satellite Constellations Based On GPU Acceleration

With the development of China's aerospace industry and communications technology,the development of national development strategies such as “One Belt and One Road” is necessary to provide reliable communications to the deep ocean,polar regions,and “One Belt and One Road” regions.In addition,for instance,foreign leading companies such as Space X are also carrying out low-orbit-constellation projects such as high-speed bandwidth Internet constellations,and building a low-orbit satellite constellation communication system capable of global coverage will be the only way for the development of China's aerospace industry.Therefore,this paper is based on a loworbit satellite constellation and the deployment of multi-beam forming antennas.The correlation between the constellation coverage and the gain and carrier-to-interference ratio of each beam coverage area is studied.The GPU parallel computing technology is used to improve the simulation efficiency.Antenna design and constellation demonstration work are of great significance.The main content of this article is:First,the time system and coordinate system involved in this paper are introduced,and the transformation relationship between coordinate systems is analyzed and solved.In the coordinate transformation from the epoch inertial system to the geocentric system,a transformation matrix based on the IAU2000 astronomical parameters involving precession,nutation,polar movement,and rotation of the earth was established.Based on this,the concept of SGP4 orbital model and double-row element is introduced.The SGP4 orbital model was implemented and compared with the commercial software STK for orbital position and sub-satellite point.The results show that the orbit model and coordinate transformation are extremely accurate.Second,the GPU parallel computing theory is introduced.The SGP4 track is modularized and the SGP4 track parallel computation flow is designed based on the CUDA computing platform.Compared with the CPU calculation results,the accuracy and operation efficiency.The results show that the CPU is superior to the GPU in terms of calculation accuracy,and in terms of computational efficiency,the GPU is higher than the CPU when it is input at more than 200 stars.Thirdly,the pointing vector of the simultaneous pointing vector and the earth ellipsoid equation are established,and a high-precision satellite-borne antenna pointing algorithm is established,and the accuracy analysis under the influence of the shape of the earth ellipsoid is performed.Based on a low-orbit satellite constellation and its deployed multi-beam antenna,the beam main lobe shape extraction and coverage gain calculation are realized.In addition,the coverage and overlapping of even-numbered orbital surfaces in high latitude areas were conceived and simulated.A beam switching strategy was developed for the coverage overlap calculation results.Based on the optimization results,the antenna design was proposed.Finally,based on the multi-beam antenna itself,the carrier-to-interference ratio of the main lobe of each sub-satellite antenna is simulated.The method of grid interpolation and inverse distance weighted interpolation of the earth's latitude and longitude was introduced,and a calculation method for the carrier-to-interference ratio of each frequency band in the multi-star scenario was designed.By comparing the characteristics of the carrier-to-dry ratio in the case of single star and multi-satellite,22 beams were interfered and 18 interference beams were analyzed.The suggestions for the optimization of the interference situation were put forward.In this paper,the satellite orbit calculation,antenna orientation and gain of multibeam antenna,carrier-to-interference ratio,and beam overlap calculation are combined.The GPU parallel computing technology is used to accelerate the orbit simulation process and realize the coverage characteristics of a certain low-earth satellite constellation multibeam antenna for ground coverage.Calculation and analysis have guiding significance for the design of this type of antenna.