An overview of the application of smart antennas in DS-CDMA systems, including IS-95 and IS-2000, is presented. Since
CDMA systems are interference-limited, adaptive antenna arrays have great potential for improving the performance of such
systems in terms of capacity, coverage, and quality of service. In this paper, we study the multiple-access interference that
affects a CDMA system, and we describe how smart antennas can be implemented in an IS-2000-based mobile communica-
tions system. When smart antennas are used at the base station to transmit in narrow beams, the interference on the
downlink is reduced, and Cjl is improved. This, in turn, increases the system capacity on the downlink or, alternatively, the
quality of service is improved. Such gains will prove very beneficial for asymmetric high-speed data applications. requiring
much higher bit rates on the downlink than on the uplink. By reducing the base-station receiver's sensitivity, smart antennas
can boost the capacity of the reverse link. Results are presented that outline how this reduction can be employed by the
system designer on the uplink to increase capacity, reduce the mobile transmit power, or effect a tradeoff between capacity
improvement and coverage or range extension under different system-loading scenarios.
