Channel precoding and low-density parity-check codes for magnetic recording

At the extremely high-linear-density regime, where +-+ appears to be the dominant error event at the detector output, two complementary methods are presented to improve the performance of iterative detection/decoding schemes based on LDPC codes. First, without increasing complexity, noticeable performance gains can be obtained by using a 1/(1 /spl oplus/ D) precoder for the partial response channel. Second, selecting a longer partial response target provides substantial additional gains.