Decision feedback equalization and channel coding for multilevel modulation

A new radio system architecture combining a decision feedback equalizer and soft decision threshold decoder has been developed. The architecture is presented for a bandwidth efficient MQAM constellation. This new architecture permits the decision feedback equalizer to use the results of the decoder in both the error estimation and the post-cursor ISI cancellation. Feedback decision error rates are thus much smaller than with the usual channel decisions. At low signal to noise ratios, performances are much improved. The simulation of this system with a rate 3/4 self orthogonal convolutional code and 16 QAM on a Rummler (1978) channel model has shown coding gain improvements of 1 dB over independent equalizing and decoding