Prediction of the differential rain attenuation induced by an adjacent terrestrial system on a site-diversity satellite system using frequency re-use

The differential rain attenuation is a significant propagation effect potentially degrading the interference between systems in the fixed-satellite service and radio-relay systems using the same frequency band. In this paper, a method to predict the carrier-to-interference ratio (CIR) degradation due to rain differential attenuation valid for single/double site diversity systems operating in a single polarization, is extended to include diversity systems operating in a dual polarization mode. The modified method is again based on a model of convective rain cells as well as on the lognormal assumption for the point rain rate distribution at the location under consideration. Another important point of the paper is the presentation of some simple parametric expressions for the calculation of CIR statistics. Numerical results are presented concerning simulated interfered satellite links using both double site diversity and frequency re-use technique. Because of lack of available experimental data, our attention has been concentrated on the examination of the reliable design and the optimum coordination between the adjacent systems. Some very useful conclusions are deduced.