Prediction of Triple-Site Diversity Performance in Earth-Space Communication

In heavy rain climatic regions (e.g., climatic zones F, H, K, L, M, N, P given by C.C.I.R.) attenuation caused by rain presents a great problem for satellite communications, at frequencies above 10 GHz. Double-site diversity is an available method to reduce the rain outage time for these systems. In some severe cases, double-site protection can be proved to be inadequate and consequently triple-site diversity becomes indispensable. In this paper, a first approach is presented for estimating the improvement in rain outage performance caused by triple-site diversity protection. The method is based on the lognormal assumption for the point rainfall rate distribution at the location under consideration. Experimental results taken from some parts of the United States such as New Jersey, Florida and Atlanta, Georgia are compared with the theoretical values and the agreement was found to be encouraging.