Further results on 3G CDMA transmit adaptive arrays

Abstract

Transmit adaptive arrays (or "TX AA") have been shown previously to provide significant capacity improvements over open loop diversity techniques. This paper expands TX AA to utilize multiple antenna elements, compares the theoretical performance to open loop diversity, and examines techniques to reduce the feedback data rate. Results are presented for high data rate traffic channels operating on the third generation (3G) CDMA IS2000 1X air interface (an IS-95 CDMA family direct spread system with 1.25 MHz bandwidth). The results show that TX AA obtains substantial gain over open loop diversity, especially when 4 elements are used. The feedback reduction techniques are shown to provide significant increases in the maximum mobile velocity where TX AA can operate for a given feedback data rate.