Decision Feedback Equalizer (DFE) modeled as a linear transversal filter

Decision Feedback Equalizer (DFE) is a very commonly used post-equalizer in communication systems as an Electronic Dispersion Compensation (EDC) technique. DFE is particularly relevant in the context of Plastic Optical Fibre (POF), which is a highly dispersive analog channel, as it uses feedback taps to address the pre-cursor Inter Symbol Interference (ISI). POF has all the positive attributes of Glass Optical Fibre (GOF) except for its high attenuation and multimodal dispersion which constrain its bandwidth and reach severely. The affordability of POF technology and its ease of use, make it an apt candidate for further investigating - how to enhance data rate, in short haul POF links like in fiber-to-the-home (FTTH). Lot of research is going on to deliver higher date rate at a longer distance using POF. Typically a target distance of 100m gives it a definite edge over other existing technologies in the short haul domain. Particularly in the context of POF, most research papers recommend DFE as the best suited equalizer - given its simplicity and for it being computationally less resource intensive. However, texts and research papers depict the DFE as a nonlinear filter (owing to the inherent decision device) with a negative feedback. This paper contends that DFE actually is a linear transversal filter with a positive feedback.