Design of LDPC codes for two-state fading channel models

We consider a two-state fading channel model and the design of LDPC codes for this model. Under certain assumptions, the model leads us to what we call the burst-erasure channel with AWGN (BuEC-G), in which bits are received in Gaussian noise or as part of an erasure burst. To design codes for this channel, we take a "shortcut" and instead design codes for the burst-erasure channel (BuEC) in which a bit is received correctly or it is received as an erasure, with erasures occurring in bursts. We show that optimal BuEC code ensembles are equal to optimal binary erasure channel (BEC) code ensembles and we design optimal codes for these channels. A given code on the BuEC may be characterized by the maximum resolvable erasure-burst length, L_max, and we present a simple algorithm for computing this parameter. Finally, we present error-rate results which demonstrate the superiority of our codes on the BuEC-G over other codes that appear in the literature.