(Blind) adaptive equalizers with soft decision feedback

In this paper, a new approach based on joint entropy maximization is considered and adaptive decision feedback equalizers are developed for equalization of complex linear channels. The proposed work generalizes the existing (blind) algorithms for DFE with a hard decision device. Previous research has shown that when the hard decision device in a DFE is replaced with soft decisions, the performance of the adaptive algorithms improves dramatically. The soft decision can be introduced naturally via the viewpoint taken here; additionally, constant modulus and other (blind) algorithms for DFE with the soft decision can be derived from this joint entropy maximization approach.