Fade durations in satellite-path mobile radio propagation

Abstract

Fades on satellite to land mobile radio links are caused by several factors, the most important of which are multipath propagation and vegetative shadowing. Designers of vehicular satellite communications systems require information about the statistics of fade durations in order to overcome or compensate for the fades. Except for a few limiting cases, only the mean fade duration can be determined analytically, and all other statistics must be obtained experimentally or via simulation.

This report describes and presents results from a computer program developed at Virginia Tech to simulate satellite path propagation of a mobile station in a rural area. The simulator was developed using 869 MHz balloon data provided by Wolfhard Vogel of the University of Texas at Austin and was tested using helicopter data provided by Wolfhard Vogel and Julius Goldhirsh of the Johns Hopkins University Applied Physics Laboratory. It generates rapidly-fading and slowly-fading signals by separate processes that yield correct cumulative signal distributions and then combines these to simulate the overall signal. This is then analyzed to yield the statistics of fade durations.