A reduced rank MMSE receiver for a DS-CDMA system in frequency selective multipath

A new reduced rank adaptive algorithm, for asynchronous DS-CDMA interference suppression in the presence of frequency selective multipath interference is presented. The algorithm employs a computationally efficient, correlation-subtraction architecture based on the multistage Wiener filter. It is shown that with enough sample support, this reduced rank technique performs as well as the full rank MMSE solution without requiring matrix inversion, eigendecomposition, or the construction of blocking matrices. At low sample support, the MWF performance is shown to exceed that of MMSE with the additional bonus of reduced complexity. System performance is characterized for a highly loaded asynchronous DS-CDMA system in the presence of multipath interference and the performance of the multistage Wiener filter is compared to the MMSE and RAKE receivers.