A Performance Comparison of VSCA and VSDA Adaptive Equalization Algorithm using Distance Adjusted Approach in QAM Signal

This paper compare the VSCA (Variable stepsize Square Contour Algorithm) and VSDA (Variable stepsize Square contour Decision directed Algorithm) adaptive equalization algorithm that is used for the minimization of the inter-symbol interference which occurs in the time disperse channel for the transmission of 16-QAM signal.. In the SCA, it is possible to compensates the amplitude and phase in the received signal that are mixed with the inter-symbol interference by the constellation dependent constant by using the 2nd order statistics of the transmitted signal. But in the VSCA and VSDA, it is possible to the improving the equalization performance by varing the step-size using the concept of distance adjusted approach for constellation matching. We compare the performance of the VSCA and VSDA algorithm by the computer simulation. For this, the equalizer output signal constellation, residual isi, maximum distortion and MSE were used in the performance index. As a result of computer simulation, the VSCA algorithm has better than the VSDA in every performance index.