Mismatched finite-complexity MMSE decision feedback equalizers

Abstract

Closed-form expressions that quantify the degradation in the decision-point signal-to-noise ratio of the finite-length minimum mean-square-error decision feedback equalizer (MMSE-DFE) due to channel and noise mismatch conditions are derived. The analysis is further extended to other receiver structures, namely, the MMSE-DFE with an adaptive feedforward filter, the MMSE linear equalizer, and the discrete multitone transceiver, all under a finite-complexity constraint. The limiting case of infinite-length filters is also analyzed. In addition, we present computer simulation results that compare the performance of the various receiver structures under study, assuming a particular channel and noise mismatch model for the high-bit-rate digital subscriber loop environment. Finally, several methods that can be used to mitigate the effects of mismatch are outlined.