Reduced-rank detection schemes for DS-CDMA communication systems

Several reduced-rank detection schemes for direct-sequence code-division multiple access (DS-CDMA) communication systems are compared. After the simplification of the auxiliary vector filtering (AVF) algorithm (Pados and Batalama 1999), it is shown that the AVF algorithm is equivalent to the multistage Wiener filtering (MWF) algorithm of Honig and Goldstein. Furthermore, these schemes can be shown to be equivalent to the multistage linear receiver scheme based on the Cayley Hamilton theorem. The analysis of the reduced rank techniques is extended to multipath fading channels. In particular, a modified reduced rank etection scheme is proposed which outperforms an isolated path combining strategy. In addition, the output signal-to-interference ratio for the noncoherent equal gain combining linear receiver is analyzed to facilitate the study of the tracking behavior of the reduced rank receivers.