Propagation modeling and system strategies in mobile-satellite urban scenarios

Land mobile satellite (LMS) systems require fade countermeasure techniques since they suffer from limited fade margins and severe channel degradations. In the view of complete statistical models for LMS systems in urban areas, this paper deals with several specific mobile satellite urban configurations, such as a long straight street lined on both sides by buildings and a crossroad. Propagation effects are modeled as time series of received power by means of a ray-tracing method, which is used in combination with an orbit generator. The time series results are then postprocessed to simulate the impact of propagation mechanisms and satellite motion on fade mitigation techniques, satellite handover, and diversity. This original approach inherently accounts for the correlation between a number of very different but simultaneous effects that influence system performance. Exemplary results are finally discussed to stress the capability of the time-series approach.