Two-level coding based on trellis-coded modulation and Reed-Solomon codes

A number of two-level codes based on trellis-coded modulation (TCM) schemes and their matched single or double error-correcting Reed-Solomon codes using QAM constellations are presented and evaluated. Compared to the well-known 4D 16-state TCM scheme with a comparable bandwidth efficiency, these two-level codes provide greater immunity from both Gaussian and impulse noise, at the cost of a reasonably higher complexity and a longer decoding delay, on the order of a few hundred symbols. The authors also show how to cope with phase ambiguities of the constellation in these two-level codes. Both rotationally invariant coding and rotation detecting techniques are considered