Site versus orbital diversity: performance comparison based on propagation characteristics at the Ku band and above

Site and orbital diversity are effective techniques to mitigate rain fades for high availability satellite communication systems located in heavy rain climatic regions operating at Ku band frequencies and above. Their performance is mainly affected by geometrical separation parameters, i.e., the separation distance between Earth stations and the angular separation between satellites, respectively. A simple model, compatible with the suggestions of ITU-R, is presented for the technical choice between the two diversity techniques yielding the same joint probability of exceeding rain induced attenuation or, equivalently, the same diversity gain. The proposed prediction model is tested against simulated data from Italy, with encouraging results.