An Adaptive Step Size Power Control with Transmit Power Control Commands Aided Mobility Estimation

Abstract

Power control is one of the most important mechanisms influencing on the maximum capacity and performance of Wideband Code Division Multiple Access (WCDMA) systems. Power control algorithms used in Universal Mobile Telecommunication System (UMTS) are based on fixed step size algorithms. The algorithms adjust their transmitted power based on Transmit Power Control (TPC) commands. In this paper, we show that there is a significant correlation between TPC sequences and user mobility. We then introduce a new parameter called Consecutive TPC Ratio (CTR), which will be varied by user speeds. A new adaptive power control algorithm is also proposed. This new power control algorithm uses CTRs to adjust power control step sizes. The result shows that the proposed algorithm outperforms fixed step power control.