Two efficient adaptively varying modulus blind equalizers: AVMA and DM/AVMA

Among the blind channel equalization schemes, constant modulus algorithm (CMA), due to its robustness and easy implementation, is an excellent choice to correct the distortions caused by transmission channels. In two-dimensional communication systems, phase recovery is a subject of grave concern which cannot be handled by conventional CMA due to its phase blind nature. In this paper, an adaptively varying modulus algorithm (AVMA) is presented that accomplishes blind equalization and phase correction simultaneously in case of light distorted channels. In order to equalize the channel with higher distortion levels, DM/AVMA, a hybrid of MCMA and AVMA is also presented. Both of these equalizers outperform the conventional CMA and some other existing schemes under certain environments. Analysis and simulation results indicate that the AVMA blind equalizer has faster convergence rate and better steady state performance than those of the conventional CMA & MCMA equalizers in light distorted channels, while, the DM/AVMA equalizer outperforms all the above-mentioned equalizers significantly in channels with higher distortion levels.