Digital Communications in Additive White Symmetric Alpha-Stable Noise

Abstract

The conventional additive white Gaussian noise (AWGN) model adequately models many noisy environments. The performance of digital communication schemes in the presence of AWGN has been widely studied and optimized. However if the noise is impulsive, this model fails to mirror the physical attributes of the channel. Impulsive noise is non-Gaussian in nature and is modeled well by random processes based on heavy-tailed symmetric α-stable (SαS) distributions. If the noise samples are independent and identically distributed (IID), the additive white SαS noise (AWSαSN) process may be used to model the channel.

In this thesis, we analyze and propose good design methodologies for uncoded digital communication systems operating in passband AWSαSN. The discussion incorporates linear and non-linear receiver schemes for single-carrier and multi-carrier communications. In conjunction with efficient constellations and suitable baseband detectors, a linear receiver may be optimized to offer much better error performance than conventional implementations. However, it is a known fact that linear systems are far from optimal in impulsive AWSαSN. By employing suitable non-linear receivers, we show that the uncoded error performance of the system may be increased significantly.