Research On Power Control Of Radio Resource Management In WCDMA System

Power control is one of the most important radio resource management technologies in WCDMA (wideband code division multiple access) system. Power Control not only effectively overcome the "near-far effect", but also could reduce the multiple-access interference, and improve the system capacity. In addition, the power control has a direct impact on the realization of CAC. CAC technology can optimize the data transmission, in order to increase the overall probability of call admission, it makes the system to meet more calls'bandwidth when the system work close to full load. The two technologies are optimized and the radio resource utilization is enhanced at the same time. In this paper have mainly done two researches on optimization power control:Firstly, introduce the principles and methods of power control and CAC technologies as well as using of the two technologies in the WCDMA system. Analysis the shortcomings of the traditional closed-loop power control. In view of SIR parameter is difficult to predict and it is the major impact on the performance of traditional closed-loop power control. Basing on this parameter the author used a power control algorithm. this method permit not to know each mobile station'transmitter power in every moment, the system can response effectively at every random situation and more accurate prediction capabilities, especially this method is more feasible. Simulation results show that the method can be smaller mean square error of power control, and have a rapid convergence.Secondly, introduce the realization of CAC under ideal conditions. It is on the basis of optimization power control. In this paper analysis a CAC algorithm in WCDMA system, and point out the call blocking problems in this algorithm. In view of this problem , the author proposed a CAC method basing on the switching degraded, the method give more priority of switching call and reduce switching failure probability, it also make the system to meet user requirements. Simulation results show that the introducing of power control technology and switching degrede admission control can greatly improve the call failure rate, so only use switching technology in CAC is far from sufficient, the system also need a power control technology to improve wireless Link quality, and to increase system capacity.