Least-symbol-error-rate adaptive decision feedback equalization for underwater channel

The decision feedback equalizer (DFE) has been applied in underwater channel equalization and has been shown to have promising performance. Existing DFEs for underwater communication are mainly based on the minimum-mean-square-error (MMSE) criterion. In this paper we derive a new DFE based on the minimum-symbol-error rate (MSER) criterion. The problem is formulated as minimizing the norm between two subsequent adaptations. The MSER criterion is converted to the constraint of correct symbol detection. The resulting DFE has a simple structure, similar to the conventional LMS filter. Moreover, simulations show it significantly outperforms the MMSE based DFEs.