Rotationally invariant trellis coded modulation system

摘要

A trellis-coded modulation system is provided in which the output of the trellis encoder (110) is used to select a subset of a multidimensional QAM constellation. The selection process is performed such that a) the minimum square Euclidean distance between valid sequences of successive selected subsets is maximized, b) the resulting code is rotationally invariant, and c) the selected subset corresponding to a transition of the trellis encoder from a present state i to a different next state j is different from the selected subset that corresponds to a transition of the trellis encoder from a present state j to a next state i.