A decision feedback filter

Due to its low complexity and robust performance, the decision feedback equalizer (DFE) continues to play an important role in high data rate and/or low cost systems, e.g., digital subscriber lines, magnetic recording and (possibly) mobile radio. Here we examine the possibility of recursive equalizers which perform soft-decisioning with complexity comparable to the DFE. The approach taken here involves initially making decisions like a DFE, followed by post filtering of these decisions using a recursive (conditionally) linear filter structure; we call this a decision feedback filter (DFF). Significantly, the DFF can be set-up to provably retain the performance capability of the DFE at high SNR, and empirically has improved performance over a wide range of SNR