A novel method for using adaptive array antennas in DS-CDMA mobile radio systems

The technology of Direct Sequence Code Division Multiple Access (DS-CDMA) has been chosen for mobile communication systems because of numerous advantages. A major advantage is that it can provide a better capacity compared to the other possible technologies of multiple access. In spread spectrum system the signal bandwidth is increased to a value much larger than is needed to transmit the underlying information bits. There are many reasons for doing this: The spread spectrum technique can hide a signal below the noise floor, making it difficult to detect. It also mitigates the performance degradation due to intersymbol and narrowband interference. In conjunction with a RAKE receiver, spread spectrum can provide coherent combining of different multipath components. In this paper, a novel method of incorporating steered beam adaptive arrays in Direct Sequence Code Division Multiple Access (DS-CDMA) spread spectrum systems is presented, and the performance of the system is investigated. It will be shown that the proposed system provides better performance (lower bit error probability) in comparison with the conventional DS-CDMA detector, especially in presence of intentional interference signals or with high cross correlation interference signals.