A Distributed SIR-Based Power Control Algorithm for WCDMA Systems

Power control has been an important issue in multiple access systems allowing more users to share the system resources. The capacity of the WCDMA system is limited by the total interference, called multiple access interference (MAI). An efficient power control algorithm is always required to improve the system performance. In this paper, we propose a distributed, first order power control algorithm. The proposed algorithm uses an exponential function with a modified form of the LMS algorithm in order to achieve a better speed of convergence. We examine the proposed algorithm for time varying multipath Rayleigh fading environment. We compare the performance of the proposed algorithm and the 3GPP standard algorithm. We demonstrate that the proposed algorithm achieves better convergence and saves on the signal-to-noise ratio (SNR) required to achieve a certain performance. We also demonstrate that the proposed algorithm works well for different mobile speeds with a continuously changing channel.