The MAP Implementation in Logic Circuits for Soft-Decision Decoding of MTR Codes

Maximum a posteriori (MAP) algorithm and decoding with min-max approximations in Boolean logic circuits, had been independently considered as soft-decision decoding methods for maximum-transition-run (MTR) codes. These two approaches are confirmed as quite valuable, enabling MTR decoder to handle soft-values in framework of iterative decoding. In this paper further research of these methods has been made and novel idea of MAP algorithm utilization into logic circuits, of new MTR soft-decision decoder, is presented. The proposed concept is considered with simple and well know rate 4/5 (2, k = 8) MTR code over E²PR4 magnetic recording channel. The non-log and log MAP implementation results with equal performance, while max-log version results with 1.6 dB of coding gain, for BER = 10^-5.