A class of block-iterative equalizers for intersymbol interference channels

A new and efficient class of nonlinear equalizers is introduced for intersymbol interference (ISI) channels. These “iterated-decision equalizers” use an optimized multipass algorithm to successively cancel ISI from a block of received data and generate symbol decisions whose reliability increases monotonically with each iteration. Asymptotically they achieve the performance of maximum-likelihood sequence detection (MLSD), but only have a computational complexity on the order of a linear equalizer (LE). And because their structure allows cancellation of both pre- and post-cursor ISI, iterated-decision equalizers outperform the minimum mean-square error decision-feedback equalizer (DFE) by 2.5 dB on severe ISI channels even with uncoded systems. Even more importantly, unlike the DFE, iterated-decision equalizers can be readily used in conjunction with error-control coding, making them attractive for a wealth of applications