Convex combinations of adaptive algorithms for blind equalization of QAM signals

Based on concurrent algorithms and on the convex combination of one slow and one fast CMA (Constant Modulus Algorithm), we propose a convex combination of two blind equalizers adapted respectively by CMA and the modified SDD (Soft Decision-Directed) algorithm for recovering of QAM (Quadrature Amplitude Modulation) signals. For high signal-to-noise ratio, the performance of the proposed scheme is, in the worst case, as good as that of the best of its components, being better than both of them in some situations. Since the considered algorithms are derived from different criteria, the mixing parameter is updated for minimizing the decision-directed cost function. Keywords— Adaptive filtering, blind equalization, QAM signals, convex combination, Constant Modulus Algorithm.