Research On CDMA Power Control System Based On Fuzzy Logic Control

Recently,the mobile communication industry is paid much attention due to the development of information technology.DS-CDMA(Direct Sequence-Code Division Multiple Access) technology is generally applied into the third generation mobile communication system.Such as the TD-SCDMA,which is developed by the domestic scientists independently,could supply kinds of businesses to the customers including data transferring,pictures,videos etc.All of these make the people life more convenient.So,it is quite important no matter theoretically or practically to develop the CDMA system.As one of the most important techniques for CDMA,the Power Control Algorithm is paid extreme attention by the researchers.That is why this paper focuses on the power control research.Comparing the proposed algorithm to the traditional ones,this paper mainly discussed the application of fuzzy logic control technology on CDMA power control system and firstly gave a basic fuzzy power control algorithm with variable step coordinating ability.Meanwhile,the round-trip time delay handling mechanism was also added into the basic fuzzy control algorithm.At last,this paper proposed the unified fuzzy power control algorithm based on merging inner and outer algorithm together.It is indicated by the simulating results that the algorithm this paper proposed has a better performance than the traditional ones.The primary work and innovation are described as follow:First,by using the fuzzy control technology which is one branch of the control theory,the algorithm could combine the fuzzy logic and CDMA power control into together.What's more,the basic fuzzy logic power control algorithm is proposed by making use of the general methods of designing a fuzzy controller.With the given fuzzy logic methods,it will make the algorithm obtained the "Variable step" ability naturally,which also improves the control precision extremely.Second,the round-trip time delay of CDMA system has a big impact to the system performances,but due to the complexity of the mobile communicating environment,the traditional power control algorithms have less solutions towards the time delay.This paper gave the solutions on the round-trip time delay based on the proposed fuzzy logic control algorithm by using phase plane analyzing methods which required to modify the related fuzzy control rules.Finally,combining the time delay handling mechanism,this paper proposed the unified power control algorithm based on merging of inner and outer algorithm together.That makes the power control algorithm more consummate.Meanwhile,to enhance the control precision,the final proposal also introduced the fuzzy weighting controller in,making the algorithm more and more integrated,which also helpful to the development of fuzzy logic theory.This paper testified the proposed algorithms in the simulating part.Comparing the proposed algorithm to the traditional ones,it is said that the fuzzy logic control proposal has a big improvement on the system performances.By simulating with the SIR threshold,outage probability and system capability,the unified power control algorithm has huge advantages on the aspects of system capability expanding.