Combined Adaptive Antenna Array and RAKE Receiver

Abstract

An adaptive beamformer used to excise broadband interferences in the direct sequence spread spectrum(DSSS) system is presented. A beamformer is a smart antenna that is able to null interfering signals while maintaining desired signals. The algorithm of adaptation is based on least mean squared (LMS) method. The reference signal used in LMS minimization is found by the projection technique. The performance analysis of the presented adaptive antenna array used to the DSSS system is given to derive an expression of probability of bit error in comparison to the bit error rates (BERs). The RAKE receiver for code division multiple access (CDMA) is a time diversity technique in that the multipath signals can be combined constructively to mitigate the effect of fading. We apply the antenna array to improve the performance of the RAKE receiver in multipath environments. Simulations are done to illustrate the decreased BERs compared to the BERs obtained by using the conventional RAKE receiver.