Mitigating Error Propagation in Decision Feedback Equalizers for VSB-Based DTV Receivers

Decision feedback equalizer (DFE) is an efficient scheme for suppressing intersymbol interference (ISI) in vestigial sideband (VSB) based digital TV (DTV) receivers. However, it suffers from the phenomenon of error propagation (EP). This paper considers the use of soft decisions in mitigating EP in a DFE. An optimized soft decision algorithm using the hyperbolic tangent function in the decision device is proposed to improve performance over reducing EP. Furthermore, in order to speed up the EP simulation process, a simple but effective modification is made in the feedback tap weight updating process. Computer simulation results show that the proposed soft decision algorithm nearly meets the ideal DFE (i.e., without erroneous decision) performance, which is far better in performance when compared to the erasure algorithm.