Dithered signed-error CMA: the complex-valued case

Adaptive blind equalization has gained widespread use in communication systems that operate without training signals. In particular, the constant modulus algorithm (CMA) has become a favorite of practitioners due to its LMS-like complexity and desirable robustness properties. The desire for further reduction in computational complexity has motivated signed-error versions of CMA, which have been found to lack the robustness properties of CMA. Previously we have presented a simple modification of real-valued signed-error CMA, based on the judicious use of dither, that results in an algorithm with robustness properties nearly identical to those of real-valued (unsigned) CMA. This paper extends those results to the complex-valued case.