1Non-Binary Message-Passing Algorithms for Magnetic Channels with Data-Dependent Noise

Abstract—The paper proposes an implementation of the mes-sage passing algorithm adapted to iterative channel detection. The algorithm uses soft messages associated to non binary symbols in order to cancel cycles in the equivalent Tanner graphs, achieving optimal performance after a low number of iterations. This architecture, suited to very fast channel detectors, is applied to magnetic recording channels and adapted to the non stationary nature of the magnetic media noise. Index Terms—Iterative decoding, low-density parity-check (LDPC) codes, maximum a posteriori decoder, message-passing algorithm, partial-response channel. I