The Research Of Joint Power Control In The Third Generation Mobile Communication Systems

CDMA is a kind of modulation and multi-access technology which bases on spread spectrum communication. It has several virtues such as high efficiency of spectrum, soft capability, good performance in secrecy, seamless handoff and macro diversity, and so on. However, the spread spectrum codes that consumers use are not orthogonal completely, multi-access interference among consumers brought by non-zero cross correlation will affect capability and performance of systems directly. Power control and multi-user detection are key techniques in order to improve capability in the CDMA mobile communication systems that get rid of near-far effect and multi-access interference.In this paper, the basic model of the traditional power control algorithm used in CDMA system is expanded, and the multi-user detection is introduced into the power control. Simulation experiments prove that joint power control algorithm based on MMSE multi-user detection has many more improvements in system performance than the traditional power control algorithm. Then another joint power control algorithm based on MSE is put forward, what's more, an effective joint power control algorithm combines the algorithms based on SIR and MSE, and solves limited increase of system capability in the joint power control algorithm based on MMSE multi-user detection and limited rate of algorithm convergence in the joint power control algorithm based on MSE.