Signal-to-interference ratio of CDMA in low Earth-orbital satellite communication systems with nonuniform traffic distribution

The performance of a satellite communication system in which the satellites are in non-geostationary orbits, with nonuniform geographical distribution of the traffic load is estimated through analysis. It is shown that when CDMA is applied to the reverse link, the traffic nonuniformity results in a large difference in the signal qualities. The signal above a dense traffic area has a low signal-to-interference ratio (SIR), while the signal over a sparse traffic area has an excessive SIR. In addition, a traffic assignment scheme, which makes the load of the satellite over the dense traffic area smaller, is proposed and its performance improvement is estimated