The MAP in LC concept for MTR decoding in multiple-head magnetic recording systems

The constrained capability of maximum-transitionrun (MTR) codes are well known in magnetic recording systems. Unfortunately, these codes possess just a modest error correcting ability and thus they have to be used in combination with proven and powerful error correcting codes. In modern, iterative decoding framework, two decoders exchange soft-information, in order to improve their decisions. Thus, the utilization of MTR codes in such framework requires some approaches for their soft-decision decoding. Recently, the MAP in LC method is proposed for such purpose, enabling propagation of soft-values through the MTR decoder. Substantial benefits have been noticed when the MAP in LC was used in a one-track MTR encoded E²PR4 magnetic recording channel. In this paper, performance and benefits of the MAP in LC, along with its two subversions, are considered over a multiple-track E²PR4 channel, encoded by the in-track MTR code. In case of the low-level inter-track interference, the subversion named as max-log MAP in LC shows nearly 0.85 dB of decoding gain, for BER = 10^-5, when 4/5 (2, 8) MTR code was used.