Time varying interference statistical distribution for direct-to-user satellite applications

Adjacent co-channel satellite systems might lead to unacceptable mutual radio interference levels due to their close spacing in orbit and to the reduced antenna sizes at the user´s reception. Tropospheric propagation impairments along with the interference effects are of utmost importance for the reliable design of modern satellite communication systems operating at Ku (14/12 GHz) and Ka(30/20 GHz) frequency bands and above. The objective of this Letter is the presentation of a novel analytical and accurate methodology for the prediction of the time varying carrier-to-interference ratio (CIR) statistical distribution under rain fading conditions. Appropriate physical space-time structure is employed for the correlation between the rain-induced attenuations on the two converging slant paths. The analysis proposed is flexible and incorporates various operational and geometrical parameters of the interference scenario. Numerical results illustrating the impact of those parameters on the space-time varying CIR statistics are presented and useful conclusions are drawn.