Density evolution analysis of LDPC codes with different receivers on impulsive noise channels

In conventional communication systems, the additive noise at the receiver is usually assumed to be Gaussian distributed. However, this assumption is not always valid and examples of non-Gaussian distributed noise include power line channels, underwater acoustic channels and man-made interference. Therefore it is important to design a receiver to mitigate the effects of impulsive noise. This paper proposes a new low-complexity receiver design that closely approximates the optimal log-likelihood ratio demapper and performs well when the channel varies from slightly impulsive to very impulsive. Furthermore, we present a density evolution analysis and simulation results of (3, 6) LDPC code on additive impulsive noise channels, with symmetric alpha-stable probability density functions, employing different receivers to overcome the impulsive nature of the channels. Each receiver calculates or approximates the log-likelihood ratios of the received symbols, depending on whether they are optimal or sub-optimal respectively. The threshold signal-to-noise ratios of the LDPC code are derived to determine the start of the waterfall region of the bit-error rate performance and simulation results are presented to validate our density evolution analysis.