MAP decoding of MTR codes in LDPC-MTR encoded magnetic recording systems

A MAP algorithm for decoding maximum transition run (MTR) codes, using the soft-decision approach, is presented in this paper. The algorithm is based on the Bayesian algorithm, and computes a posteriori log-likelihood ratio (LLR) for output bits, using codewords of the MTR code. The log MAP and max-log MAP version of the algorithm have been developed, showing performance comparable to that of the original version. MAP algorithm offers 2 dB coding gain, in combination with LDPC, comparing to the uncoded system, while utilization of the MTR, the 25% decreasing in overall required operations of detector over E
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PR4 magnetic recording system.