Unequal error protection TCM codes

A family of unequal error protection (UEP) codes using multilevel codes and a four-way partition of a one-dimensional lattice is considered. The non-regular set partitioning combined with a nonuniform signal constellation yields codes with large minimum distance and small path multiplicity. However, this 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 while providing gain comparable to the best previously published results