Wireless Channels that Exhibit "Worse than Rayleigh" Fading: Analytical and Measurement Results

We describe several disparate practical settings in which cases of severe, or "worse than Rayleigh, "fading have been encountered. To explain this behavior, we present two physical models. The first model employs a statistically non-stationary random process that switches between two distributions, akin to the multi-state models proposed for land mobile satellite channels. The other model we propose is a multiplicative model of two small scale fading processes. We also describe the analytical pdf for such a multiplicative model using two Weibull random variables as the underlying small scale fading distributions. Measured data is used to corroborate these models, and our computer simulations confirm the ability to replicate the statistics of these severe fading processes. These proposed models can be used by researchers investigating communication system designs in severe fading environments