Performance of pcs with antenna diversity in sub-Rayleigh fading

Nakagami fading channels have been used as a very flexible, and fairly accurate approximation of realistic fading in wireless systems [1-3]. In particular, sub-Rayleigh fading, i.e. fading with severity parameter 0.5 ≤ m ≤ 1, describes situation where only a few major scatterers contribute to the signal in the antenna of the receiver, and there is no Line of Sight (LOS) present. Due to a finite spatial correlation of the incident electromagnetic field, and the movement of the vehicle, the fading process possesses certain correlation properties [13], which must be accurately represented when numerical simulation of wireless systems is considered. There are very few algorithms which allow such accurate modelling [3-5]. Most of these algorithm are either based on some numerical evaluation of the parameters of the model [4], or provide an approximation for the resulting correlation function with a fixed uncontrollable error [5]. As a result these models have limiting application in laborious Monte Carlo simulation of the wireless systems. In this paper we suggest a model which allows complete analytical description of the marginal probability density function (PDF) of the envelope and its correlation function. At the same time it provides for an accurate numerical simulation algorithm along with the possibility to derive probability density of any order. In contrast to [4], we provide analytically tractable algorithms which allows the model parameters to be found in closed form. At the same time we avoid the complications related to the representation of a correlation function as a product of two correlation functions [4]. As an example we consider application of the simulation technique suggested to a system with antenna diversity.