High bit rate digital subscriber line transmission with noise-predictive decision-feedback equalization and block coded modulation

The author presents a proposal for solving the problem of reduced performance of coded modulation due to colored channel noise by whitening the noise with an added noise predictor in the decision-feedback equalizer (DFE). This also has the benefit of increasing the nominal SNR. The resulting equalizer has a structure encompassing as a special case the noise-predictive DFE proposed earlier by others. Several numerical examples are provided to illustrate the digital subscriber line transmission performance with the new noise-predictive DFE. It is shown that the added noise predictor improves the transmission performance in two ways: first, it decorrelates the noise, and second, it decreases the noise power by its prediction gain