Reduced-rank interference suppression for DS-CDMA based on interpolated FIR filters

Reduced-rank receivers based on interpolated finite impulse response (FIR) filters for direct sequence code division multiple access (DS-CDMA) systems are proposed and a novel scheme where the interpolator is rendered time-varying is introduced. The interpolated minimum mean squared error (MMSE) and constrained minimum variance (CMV) solutions are derived for both receiver and interpolator to mitigate multiple access interference (MAI) and intersymbol interference (ISI) in a downlink scenario.