Performance Analysis of NGSO Satellite Communication Systems With Flexible Beams

Flexible spot beams have been widely utilized in satellite communication systems to project high power and reuse frequency spectrum. To improve the system efficiency, beams share the same frequency channel and are only steered to the user terminals (UTs) which need to be served. Satellites with numerous beams can serve large numbers of UTs simultaneously, which may lead to severe interbeam interference because of the nonuniform distributed UTs. Therefore, it is significant to study the effect of beam configuration parameters on the coverage performance to design an efficient satellite communication system. In this article, we derive analytical expressions for the coverage probability and the average data rate of a flexible beam using stochastic geometry tools. We model the locations of beam centers as a nonhomogeneous spherical binomial point process (NSBPP) whose intensity depends on the density of UTs. Meanwhile, the average sum rate of a satellite is derived using two different models of the locations of satellites. From the numerical results, the average sum rate of a satellite first increases but then levels off as the number of beams increases, which may provide insightful design guidelines on satellite communication systems.