Closed-loop power control performance in a cellular CDMA system

Abstract

In order to both counteract the near-far problem and maintain a constant average performance to all users in a cellular CDMA system, adaptive power control is essential. In situations where the round trip delay between the mobile and the base station is smaller than the correlation time of the channel (e.g., terrestrial systems, and systems using base stations onboard low altitude UAVs in tactical environments), power control schemes using feedback from the base station can be effective to compensate for the multipath fading. In this paper, we present the performance of such a closed loop power control (CLPC) scheme applied to a cellular CDMA system. The effect of various loop parameters, including power control update rate, loop delay due to propagation and processing, and vehicle speed, on the average bit error performance of the system are estimated through simulation. The capacity improvement due to effective power control in a single cell as well as a multi-cell CDMA system operating over both frequency non-selective and frequency selective fading channels are estimated.