Unequal error protection TCM codes

A family of unequal error protection (UEP) codes using multilevel codes and a four-way partition of one-dimensional lattice is considered. The non-reg ular set partitioning combined with nonuniform signal constellation yields codes with large minimum distance and small path multiplicity. However, thi s is not in itself sufficient for reliable coding gain estimation. New code search methods are introduced for better estimation of actual coding gain results. Codes are presented which permit resolution of phase ambiguities w hile providing gain comparable to the best previously published results.