Comparison of probability of non-visibility in case of faults of some satellites in LEO constellations

In this paper we analyze the coverage performance of satellite constellation in low earth orbit. First we analyze the various possible configurations of satellite failures in the same orbital plane or in different orbital planes when one satellite or a number of satellites are at fault. To evaluate the performance of each constellation we use one parameter, which is the maximum non-visibility time at one receiver position on Earth by using simulation software. We have also simulated the coverage performance variations depending on the receiver position on earth by varying the latitude of the receive position from 0 to 90 degrees. According to the results of the simulations we compare the maximum non-visibility time depending on the configuration of satellite and identify the worst case combination of satellite failures in satellite constellation. We also evaluate the performances the satellite constellations in 780 km orbit in case of a fault of some satellite in the same orbital plane or in different orbital plane. Finally we evaluate the some orbital manoeuvre strategy, (phase changing in the same orbital plane), to minimize the non-visibility time on Earth in case of failure of number of satellites.