Study On Blind Equalization Alogrithm Based On Bussgang Technology

In digital communication systems, intersymbol interference (ISI)is often encountered when unknown signals are transmitted through nonidea channels. In order to reducing ISI recovering transmitted signal equalizer have to be used in the reciever. Because blind channel equalizer can reduce the intersymbol interference without the assistance of the transmitted sequence, it has been becoming a very popular research topic in recent years.The constant modulus algorithm (CMA) is the most widely used algorithm in digital communication systems due to its simplicity and robustness. In this paper we analysis the inherent limitation of CMA which lead to a tradeoff between convergence rate and misadjustment, and propose several variable step size CMA by putting variable step-size theories into CMA. The convergence performance of the proposed algorithms is illustrated by computer simulations.The main works of this paper can be summarized as follows:1. In this paper, the inherent limitation of CMA is studied which greatly affect the convergence properties, variable step size thoeries is put into CMA, and several variable step size CM blind equalization algorithm is proposed which can overcome the tradeoff between convergence rate and misadjustment.2. The basic principle of variable step-size algorithm is analysed, as the facter of variable step-size algorithm MSE, the non-linear function of error signal, autocorrelation of error signal and the kurtosis of error signal is proposed, and four new variable step-size CMA is achieved.3. The kurtosis of equalizer output as a new variable step-size facter is propose, which provide an alternative method of variable step-size, and a new variable step-size CMA by putting it into CMA is achieved.