A simple alternative to the lognormal model of shadow fading in terrestrial and satellite channels

The distribution of the local average power at the land mobile is widely accepted to be lognormal in both terrestrial and satellite channels. However, the mathematical form of the lognormal distribution is not convenient for analytic calculations. In this paper, we show the utility of the gamma distribution for shadow fading, in both terrestrial and satellite channels, using empirical data. Furthermore, we show that the application of the gamma model of shadow fading, in place of the lognormal model, results in closed-form and mathematicallytractable solutions for key system performance measures such as the average symbol error rate of different modulations with a variety of diversity combining techniques.