A class of block-iterative equalizers for intersymbol interference channels: Fixed channel

A new and efficient class of nonlinear equalizers is developed for intersym bol interference (ISI) channels. These "iterated-decision equalizers" use a n optimized multipass algorithm to successively cancel ISI from a block of received data and generate symbol decisions whose reliability increases mon otonically with each iteration. These equalizers have an effective complexi ty comparable to the decision-feed back equalizer (DFE), yet asymptotically achieve the performance of maximum-likelihood sequence detection (MLSD). W e show that, because their structure allows cancellation of both precursor and postcursor IST, iterated-decision equalizers outperform the minimum mea n-square error DFE by 2.507 dB on severe ISI channels even with uncoded sys tems. Moreover, unlike the DFE, iterated-decision equalizers can be readily used in conjunction with error-control coding, making them attractive for a wealth of applications.