High performance antenna array algorithm for DS/CDMA communications

We propose a new beamforming method, which is based on eigenvalue decomposition and interference cancellation (EDIC), for the RAKE structure antenna array in DS/CDMA communication systems such as IS-95 or PCS. Our approach uses the desired signature code and the orthogonal code to decompose the receiving signals into two parts: the desired signal and interference. The beamforming weights are blindly updated according to these two sub-spaces. Unlike the null space beamforming method, the new beamformer can handle a large number of users with a small number of antenna elements. To adapt to the time varying environment, a recursive algorithm is developed at a very low hardware complexity. Monte Carlo simulations show that the new blind recursive algorithm converges very fast and has better performance than the well known generalized eigenvalue decomposition (GED) method.