Because of the fact that the effect of a symbol is

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Unformatted text preview: previously decided symbols (output from the decision device) provided that we have made correct decisions on them. This approach is called decision feedback equalization. With decision feedback, we can think of the equalizer to contain two parts — a feedforward part and a ½ ½ ½ ½ ½ ¡ ½ ½ 5 6 Assuming all the required invertibilities, ´ Of course, we need to have knowledge of Þ ´µ µ · to be able to do so. 4.17 . Wong & Lok: Theory of Digital Communications 4. ISI & Equalization feedback part. Suppose that the feedforward filter is of order Ľ · ½ and the feedback filter is of order ľ . Then ¼ Á Ľ · Á ľ ½ Á (4.46) where Á are the decided symbols. Again, the filter coefficients can be found by minimizing the MSE. In general, significant improvement over linear equalizers can be obtained with the decision feedback equalizer. Consider a DFE with a feedforward filter of order Ľ ·½ and a feedback filter of order ľ . Assume perfect decision feed...
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