MMSE non uniformly spaced equalizers

Non uniformly spaced equalizers (NUSE) were recently proposed as an alternative to fractional spaced equalizers (FSE) and baud spaced equalizers (BSE). A key result pertaining to this new class of equalizers is that, under certain channel conditions, NUSE FIR zero forcing solutions operating at the lower BSE rate exist. We extend this result by presenting necessary and sufficient conditions for generalized zero forcing FIR NUSE. We then introduce a multirate DSP structure from which any of the above equalization schemes can be obtained. By adopting this unifying framework, the minimum mean square error (MMSE) FIR NUSE is derived and discrepancies between the three equalization methods are clearly outlined.