Blind multi-user combining at the base station for asynchronous CDMA systems

This paper studies the potential benefits of antenna arrays in cellular CDMA communications and proposes a powerful scheme to undertake the array processing at the base station in CDMA mobile systems. The proposed technique exploits the temporal structure of CDMA signals. The necessary information is extracted directly from the received signals, thus no training signal or “a priori” spatial information is required. Making use of the overall information present at the receiver after the despreading, the technique presented, jointly with singular value decomposition, estimates the generalized steering vector for each user. Then, an optimal combining of the signal received at each antenna is undertaken, achieving substantial robustness against fading and near-far problems