Study On Blind Equalization In Underwater Acoustic Communication

The technique of equalization is the effective method for removing the ISI from communication systems. Blind equalization needs not training sequence, thus many scholars and experts begin to study on it. At present, studies on blind equalization focus on finding a method to search the global minimum point or choosing equalizer's structure. Every algorithm of blind equalization has its applicability according to some suppose condition. The major contribution of this paper is summarized as follow:1 .This paper systematically analyses and summarizes basic theory of blind equalization such as the qualization criterion, algorithm form and the performance parameter. Research on CMA algorithm of Bussgang algorithms is the emphasis.2.This paper analyses the convergence performance of the traditional CMA algorithm. The fixed step size of the traditional CMA algorithm makes convergence become a contradiction which makes the speed and residual error application fields of CMA.3.This paper derives an improved CMA blind equalization algorithm basing on the power of the equalizer's output signal. The simulation with computer shows the improved algorithms have better convergence performance than the CMA algorithm.4.Analyzing blind equalization algorithms based on high-orderstatistics. Giving a new method of the counterchange based on the need of symmetric -to-asymmetric transformation(SAT) during transmitting and the asymmetric-to-symmetric transformation(AST) in the receiver while employing third-second order normalized simulation cumulant algorithms to transport the symmetric signal. Then the results show that this algorithm can equalizes channel.