On the Robustness of Iterative Decoders

Robustness of iterative decoders, i.e., their ability to successfully decode the received signal in spite of unknown changes in the channel parameter, is investigated. More specifically, using low-density parity-check codes and iterative message-passing decoders for error correction, we consider reliable communication over a binary-input power-limited Gaussian channel whose noise power is not perfectly known to the receiver. We propose iterative algorithms that can decode the received signal in the presence of a strong uncertainty in the channel parameter. Such decoders are of interest for wireless applications, where the channel attenuation could significantly vary with time