Statistics of differential rain attenuation on converging terrestrial propagation paths

Rain attenuation is considered to be one of the main causes of interference impairments for terrestrial communication systems operating at frequencies above 10 GHz. A method to predict the cumulative distribution of differential rain attenuation on two converging microwave links is proposed. It is based on a convective raincells model for the structure of the rainfall medium, as well as the lognormal assumption for the point rainfall distribution. The degradation of the carrier-to-interference ratio under rainy conditions is also examined. Numerical results are compared with a set of available experimental data for the differential rain attenuation over pairs of terrestrial links in Brazil.