Design and performance of an all-digital adaptive 2.048 Mbit/s data transmission system using noise prediction

A quaternary digital transmission system for ISDN primary rate access (2.048 Mb/s, Europe) over the twisted wire pair channel is presented. The system permits more than a doubling of the regenerator space as compared to existing systems, although the transmission is affected by severe intersymbol interference and near-end crosstalk. A proposed receiver structure with the threshold detection, adaptive equalization, and adaptive, linear noise prediction achieves the performance of a maximum-likelihood sequence estimator, which would have immense complexity, within 2.4 dB. It is shown that the noise prediction gains some advantages over the conventional decision-feedback equalizer. An implementation of the receiver with high-speed digital-signal processing building blocks, which achieves an efficiency of about 72 MOPS, is described. Measurement results, which demonstrate that the theoretical bound is met within less than 0.5 dB, are presented