A new SISO equalizer for the multipath channel of downlink DS-WCDMA

This paper deals with the design of an optimum soft-input soft-output (SISO) a-posteriori receiver front-end for the downlink of direct-sequence W-CDMA cellular systems. The proposed structure yields the minimum bit error probability when used alone with hard decision at its output, and it evaluates the optimal metric (in the presence of the intersymbol interference (ISI) due to multipath propagation) to be provided to the turbo decoder. Performance of the new SISO equalizer are shown for both uncoded and coded systems in the standard framework of UMTS system