Adaptive array antenna for W-CDMA systems

The adaptive array antenna (AAA) is one of the advanced techniques that will be implemented in the IMT-2000 mobile telecommunications systems to achieve a high system capacity. This paper describes an integrated AAA system for W-CDMA that consists of both uplink and downlink beam formers. We developed three functions for the AAA: a digital beam former using the normalized least mean square (NLMS) algorithm, a two-dimensional path searcher that works at a lower reception level than the conventional one, and a calibrator that compensates for variations in the amplitude and phase of signals at antenna branches. We built an experimental test bed, conducted field trials, and evaluated characteristics of the AAA such as the compensation accuracy of the calibrator and the path search sensitivity of the path searcher. The experimental results showed that the AAA is effective enough to improve system capacity.