Joint space-time adaptive filtering for DS-CDMA systems with antenna arrays based on the multistage Wiener filter

An innovative, joint space-time pre-processor employing a RAKE structure and spatial diversity is proposed. The pre-processor allows for the amplitudes and phases of the signal components that have been distorted by multipath and fading to be combined. The multistage Wiener filter (MWF) then provides interference suppression (IS) on the reconstructed pre-processed output that exceeds MMSE performance at greatly reduced complexity. The MWF has been shown to operate at much lower rank and at greatly reduced sample support compared to any other reduced rank method. It provides the additional advantage of rapid adaptation to time-varying channel conditions and does not depend on covariance matrix estimation or eigenvector decomposition. It is demonstrated that the proposed algorithm is capable of suppressing co-channel interference and providing both multipath delay and fading compensation while maintaining low computational complexity versus existing techniques.