Fast training of fractionally-spaced modified decision feedback equalizer in slow frequency selective fading channels

To reduce the equalizer training time with robustness to the timing phase error in fixed wireless channels, we propose a fractionally-spaced modified DFE (FS-MDFE) scheme. The proposed FS-MDFE is an extension of the previously proposed symbol-spaced modified DFE (SS-MDFE) (see Ariyavisitakul, S. and Greenstein, L.J., IEEE J. Select. Areas Commun., vol.15, no.1, p.5-15, 1997). The performance of the FS-MDFE is analytically evaluated in terms of the mean squared error. The optimum MMSE solution is derived for initialization of the feedforward filter of the MDFE. We also propose a simplified initialization method to reduce the implementation complexity.