Enumerative Encoding with Non-Uniform Modulation Constraints

A reverse concatenation scheme based on an efficient modulation encoder satisfying non-uniform constraints, a systematic Reed-Solomon encoder and a partial symbol interleaver is presented. This architecture achieves very tight modulation constraints and minimizes error propagation and rate loss. The modulation constraints considered are of the same type as the constraints that have been used in generalized partial-response maximum-likelihood (PRML) detection systems. A class of codes that is based on serial concatenation of a prefix-constrained code and two interleaved enumerative codes with non-uniform constraints is proposed. Specific rate-199/200 PRML(G, I) codes are constructed.