An orthogonal projection based blind beamformer for DS-CDMA systems

Abstract

Conventional blind beamformers in DS-CDMA systems generally suffer from either unreliable convergence rate or signal cancellation in practical signal environment. In this paper, we propose a novel orthogonal projection scheme to extract spatial interference structure for the blind beamformer, which requires neither the direction of the desired signal nor the array geometry information. Exploiting more signal-free interference samples makes the convergence of the beamformer fast and independent of the desired signal strength. Simulation results demonstrate its better interference suppression ability than the pre- and post- correlation (PAPC) scheme and the filter pair (FP) scheme. Furthermore, the proposed recursive algorithm can null the newly entering interferers within a few symbols, making it suitable for dynamic multiple access channels.