A Generalization of the Enhanced Decision Adjusted Modulus Algorithm for Blind Equalization of Constellations with Closely Positioned Circles

The work is devoted to the problems of blind equalization in quadrature amplitude modulation systems. The disadvantages of typically used algorithms, such as the constant modulus algorithm (CMA) or decision-directed algorithms, are reviewed. A new approach to blind equalization is proposed in the paper. It is based on a combination of the CMA and enhanced decision adjusted modulus algorithm elements and mitigates the drawbacks of both algorithms. The algorithm uses optimally calculated detection thresholds to make a decision. The optimization criterion is the minimum probability of the equalizer weights misadjustment. The algorithm has shown high efficiency for modulations with closely positioned circles in the constellation.