Trellis coded modulation system employing a flexible trellis coded modulation decoder

A trellis coded modulation system, comprising:

• a trellis coded modulation encoder comprising a plurality of delay elements and a rate ½ convolutional encoder for processing k data bits, d(0) . . . d(k−1), the rate ½ convolutional encoder processing the least significant bit, d(0), to generate two code-bits c(0), c(1) that are indicative of a coset of symbols in the transmit symbol constellation, and a look-up table coupled to the delay elements and convolutional encoder that implements a bit-to-symbol map that outputs a single k-bit symbol corresponding to one of the 2k symbols in the transmit constellation;
• and
• a trellis coded modulation decoder for processing received symbols comprising an input lookup table for translating locations of a constellation point into a decision region label, a Viterbi decoder coupled to the input lookup table for processing synthesized soft decision data to generate a maximal likelihood estimate d'(0) of the most likely coset to which a received symbol belongs, a convolutional encoder coupled to the Viterbi decoder for re-encoding the maximal likelihood estimate of the most likely coset to generate a coset label indicative of the coset to which the received symbol most likely belongs, and an output look-up table for processing the decision region label and the coset label to output a maximal likelihood symbol that conresponds to the received symbol.