Uplink Close Loop Power Control Algorithm In 3G Wireless Communication System

Wideband CDMA has been selected as the access technique for the next generation wireless communication system. Consequently, it has received a significant amount of attention in provision of advanced algorithms for improved performance in kinds of key technology. Accurate power control is one of the most important requirements of the wideband CDMA systems, but the conventional power control algorithm is not able to track deep fading timely. In this paper, one new adaptive step-size algorithm for controlling the transmitted power of the mobile station in a CDMA-based cellular system is presented base on kinds of current adaptive step-size algorithms, like delta modulation algorithm and control bit stored in mobile receiver algorithm. The major excellence of new algorithm is to utilize a memory block to record previous power control command and decide next step-size regarding this commands pattern. The simulation result shows that the new algorithm has better performance in power control when deep fading occurrence, the STD (Standard Deviation) of power control error reduce 0.6dB with AWGN for SNR=10dB and up to 1dB without noise comparing with conventional fix step size close loop power control algorithm.