Characterization of the attenuation distribution at cm and mm wavelengths across wide areas

Using the statistical models for the distribution of the rainfall intensity across wide areas described in the companion paper [1], we present here a model to predict, instant by instant, the time-variant spatial statistical distribution of the rain attenuation starting from input information obtainable by the weather forecasts periodically distributed by the ECMWF (European Centre for Medium range Weather Forecasts) and the Meteosat meteorological satellite; predictions of distribution of attenuation across wide areas are very much sought nowadays in the design of advanced satellite systems embodying PIMTs (Propagation Impairments Mitigation Techniques) aiming at optimizing the use of the limited power available on-board by distributing the power flux over regions more affected by bad weather conditions. The spatial Cumulative Distribution Functions (CDFs) of the attenuation (applicable to a certain time interval and to elementary areas of typical dimension of the order of 100 km) are curves giving, at certain instants, the percentage of area in which the attenuation exceeds a prefixed value. For the practical use these curves are approximated by means of a suitable mathematical model and, taking into account the population density, transformed into the percentage of the non served users (NNS = Number of Non Served Users) for which the power flux incident on the Earth-terminal is not sufficient for the reception. The system optimization based on these data strives to minimize, in quasi real time, the number of the NNS across a wide area like the full Europe.