Trellis coded modulation system employing a flexible trellis coded modulation decoder

摘要

A trellis coded modulation system for use with a plurality of QAM modes that allows a choice of modulation scheme tailored to a communication channel. The system comprises an encoder and a decoder. The decoder uses input and output look-up tables that allow the use of a single decoder/encoder arrangement comprising a Viterbi decoder and a convolutional encoder to map trellis coded modulation to/from multiple modulation constellations. The size of the look-up tables used in the decoder is minimized because recognizable sequences (6 bits) are passed to the Viterbi decoder. The input look-up table provides minimal information about which region the symbol was found. The output look-up table processes the resulting information appropriately.