Maximum-Likelihood Receiver for Digital Data Transmission

The maximum-likelihood (ML) receiver for binary data, additive Gaussian noise, and nearest-neighbor intersymbol interference (ISI) is shown to be a matched filter followed by a feedback loop and a tapped delay line. The loop and the tap connections contain nonlinear amplifiers, each saturating at the level of the ISI. This receiver minimizes the persymbol probability of error Pe; upper and lower bounds on Peare obtained. The mathematical receiver specifications for multilevel data and for extensive ISI are given; an approximate structure for the latter receiver is presented as an intuitive extension of the binary, limited ISI structure.