Enforcing maximum-transition-run code constraints and low-density parity-check decoding

We present a novel algorithm for imposing the maximum-transition-run (MTR) code constraint in the decoding of low-density parity-check (LDPC) codes over a partial response channel. This algorithm provides a gain of about 0.2 dB. We also develop log and max-log versions of the MTR enforcer, similar to the well-known "log-MAP" (maximum a posteriori ) and "max-log-MAP" variants of the LDPC decoder, that have performance equivalent to that of the original version.