An interleaved coding scheme for (1-D)(1+D)/sup 2/ partial response with concatenated decoding

The Viterbi detector of a matched spectral null (MSN) coded EPR4 channel is difficult to implement at high data rates, since it requires high computational and storage power. We propose an MSN coding scheme for the EPR4 channel with interleaved encoding and suboptimal concatenated decoding. This suboptimal scheme allows much simpler implementation of the detector with negligible performance loss. The idea for interleaved encoding comes from an earlier study of the EPR4 channel distance properties, and the idea for concatenated decoding is very similar to the one already introduced for the PR4 channel.