Propagation requirements for the performance evaluation of advanced satellite systems with shared resources

This paper concerns the subject of future satellite telecommunication systems in the 30/20 GHz bands, for which an on-board common resource is envisaged, to be temporarily assigned to earth-stations undergoing severe weather conditions, as a means of alleviating the effect of strong fades due to rain. The design of such systems is significantly dependent upon the spacial distribution of rain across a very wide range of distances. Of particular importance is the probability that certain thresholds of attenuation, or equivalent point rain intensity, are exceeded simultaneously at various sites. Joint probabilities of exceedance are pointed out here as a primary objective for the future propagation activity in this field. The paper shows how they can be used to determine the system performance both in terms of probability that the number of requests exceeds the satellite capability and in terms of probability that a given station is not helped because all the resources are engaged.