Study On Adaptive Equalization Algorithm

It has become the important symbol of development the Communication technology and system, and today's digital communication technology and system have been developing from wire to wireless, analog to digital, fixed to mobile, low rate to high rate. One factor which effects data transmission is the intersymbol interference (ISI). The reason of ISI is the characteristic of a non-ideal channel. Adaptive equalization is mainly solution of dealing with ISI. Equalization must be suitable for time varying channel and transmission for time slot of data. The equalization needs the training sequence, so in some condition without training sequence the usage of the blind equalizer is necessary. The main works of the dissertation is to discuss the different technique of equalization and the simulation analysis of them. At the same time, some of these equalization algorithms have been improved and the results of simulation for these algorithms also are given. The major work and innovations done in the dissertation are shown as follows: 1. Analyzing the normal algorithms of LMS and RLS and simulating these two algorithms with Matlab. And improving the LMS algorithm, then analyzing this improved algorithm and giving the result of it. 2. Analyzing the normal CMA which is employed in blind equalization and giving the varying step-size CMA because of the slow speed of the normal CMA,and doing the simulation of the improved algorithm. At the same time, the analysis and the simulation of the improved algorithm being given based on the character of the channel tracking and the effect of the sudden strong random noise. 3. Analyzing the normalized algorithm of base on high-order statistics and discussing fourth-second order normalized cumulant algorithms and third-second order normalized cumulant algorithms. Improving the estimation of high-order cumulant in the iteration for algorithm. Giving a new method of counterchange based on the need of symmetric-to-asymmetric transformation(SAT) and asymmetric-to-symmetric transformation(AST) while employing third-second order normalized cumulant algorithms to transport the symmetric signal. There is important theoretical and actual significance for the high speed digital communication system while employing the technique of equalization to solve the problem of ISI. The technique of equalization is surely a project with great prospect.