Closed loop power control for DS-CDMA system by using Linear Quadratic Regulator algorithm

It is well recognized that power control is an important technique to combat the near far problem, the co-channel interference and the fading channel in the reverse link of direct sequence-code division multiple access (DS-CDMA). With tight power control algorithm, the system capacity and quality of service (QoS) can be enhanced. In this paper, we present the DS-CDMA model in Rayleigh fading channel concerning the effect of interference and noise and the decentralized algorithm to control the reverse link closed loop power of DS-CDMA cellular system based on linear quadratic regulator (LQR). The SINR threshold (gamma*) control level of each mobile station is individually adjusted with reference to its own radio link condition. This method resulted in lower of outage probability and enhanced traffic capacity by maintaining the reliable QoS of the system when compared with conventional power control.