Joint turbo and modulated code encoding decoding for ISI channels

Modulated codes (MC) are convolutional codes defined over the real/complex field and therefore can be naturally combined with an intersymbol interference (ISI) channel. The linear combination provides the convenience of the optimal study. It was shown by Xia (see Modulated codes for Intersymbol Interference, Marcel Dekker, New York, 2000) that for any finite tap ISI channel, there exists MC such that the MC coded ISI channel outperforms the ideal AWGN channel at low channel SNR. It is known that turbo coding approaches the AWGN channel capacity at low SNR. This motivates us to combine turbo coding and modulated coding for ISI channel with AWGN. It turns out that the combination of turbo and MC coding for ISI channel may outperform the AWGN channel capacity at low SNR.