On MMSE fractionally-spaced equalizer design

This paper adds analytical tools to an evolving theory on fractionally-spaced equalizer (FSE) design. It examines the minimum mean square error design (MMSE-FSE) for channels perturbed by additive noise in two scenarios: when the equalizer is finite, but is at least as long as the channel, and when the equalizer has an infinite impulse response (IIR). Mean square error (MSE) expressions in terms of channel parameters, roots, and spectra are derived as analytical tools for understanding the intricacies of fractionally-spaced equalization and for developing guidelines towards the design.