A dual-mode technique for improved blind equalization for QAM signals

A dual-mode blind equalization technique for adaptive channel equalization of quadrature amplitude modulation signals is introduced. The equalizer uses the constant modulus algorithm (CMA) in the initial phase and then switches to a proposed constellation-matched error (CME) minimization algorithm at appropriate values of the mean-square error. The proposed CME cost function can be constructed using finite- or infinite-order polynomials with desirable properties over the constellation region. This dual-mode equalization technique is applied to a linear equalizer and is shown to provide superior performance or simplicity over the conventional CMA and some other dual-mode schemes.