Research And Improvement On Power Control Algorithm For The Third Generation Mobile Communication System

In a wideband CDMA technology-based third generation mobile communication system, power control technology is one of the key technology,the core to promote the development of CDMA system. Power control technology can reduce the impact of interference on the CDMA system, overcome the "distance effect" and the "corner effect" in the premise of ensuring the quality of communication and improve communication system capacity.This thesis focus on power control algorithm of the third generation mobile communication system. Firstly,introduces the third generation mobile communication system development condition and key technologies,discusses the purpose, meaning and control guidelines of power control technology, along with power control technology classification and the factors affecting power control. Secondly, the paper presents the importance of power control algorithms, describes some typical and improved power control algorithms by comparing and analyzing on their characteristics. In the end, based on traditional fixed step power control algorithms, the paper proposes a novel variable step adaptive uplink power control algorithm, which taking a number of changes in control commands into account, can adjust the control step size depending on different circumstances. Thus the developed algorithm is better in compensating the attenuation of wireless channel than that with fixed step size, and can highly improve system performances. Simulation results show that the proposed adaptive variable step power control algorithm have improved a lot in both convergence performance of signal to interference ratio and bit error rate performance. Further more, the algorithm needs narrow bandwidth and simple to control and therefore has strong advantages.