An overview of propagation factors influencing the design of mobile satellite communication systems

A number of mobile satellite communication systems are currently being developed that do not make use of satellite constellations based on the traditional geostationary orbit used for communication satellites. This paper describes some of the propagation-related factors that influence the constellation for some of these systems, along with mitigation techniques that may be employed to overcome the dominant propagation-related impairments. For systems operating at VHF and UHF, the effects of mobile environment factors such as blockage and multipath are the dominant propagation factors in the link design. Mitigation techniques, such as satellite diversity, can be usefully employed to help overcome the effects of blockage, which may become increasingly severe at low elevation angles. The driving factor for constellation design is to provide a sufficiently high probability of multiple (dual or more) satellite visibility over the latitudes of interest