Minimum mean-squared error echo cancellation and equalization for digital subscriber line transmission. II. A simulation study

For pt.I see ibid., vol.38, no.1, p.31-8 (1990). A comparison is made of the transmission performance of various line codes in the subscriber line environment and at a line rate around 260 kb/s. The simulated transmission environment includes transhybrid echo, intersymbol interference, and near-end crosstalk from identical digital-subscriber-line transmission systems. The simulated transceiver incorporates an echo canceller and a decision-feedback equalizer that are optimal in the minimum-mean-squared-error sense. Both the echo canceller and the decision-feedback equalizer have a tap spacing equal to the symbol period. The line codes investigated include five block codes that offer reduced baud rates and five codes that do not reduce the baud rate. Under the conditions of this study, block codes do show an advantage over nonblock codes, with the 2B1Q block code yielding the best performance