Reverse-link power control in CDMA distributed antenna systems

It is well known that transmit power control is an essential component of any CDMA system. In conventional cellular systems, the interface between the wired network and wireless medium is the base station antenna (or closely located antennas if there is microdiversity) placed at the geographic center of the cell area. With such a "centralized" antenna, however, it is often impossible to maintain perfect power control (even if the power levels are adjusted in a precise and instantaneous manner) due to the fact that the required transmit power levels would occasionally (or often) be beyond practical limits; this is especially true for environments that yield high path losses. We investigate the peak and median transmit power requirements in a CDMA system that employs power control with a distributed antenna architecture. Computer simulations show that by using such an antenna architecture with only 4 antenna elements, the median and peak transmit power levels can be reduced by 13 dB and 20 dB, respectively. This may yield a substantial increase in system capacity, as well as a prolonged subscriber battery usage that may be critical in high data rate applications.