If we model the as iid random variables with zero

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Unformatted text preview: Digital Communications 4. ISI & Equalization In general, the corresponding impulse response can be an infinite length sequence. Suitable truncation and delay is applied to get an approximation. We note that the effect of the equalizing filter on the noise is neglected in the development of the zero-forcing equalizer above. In reality, noise is always present. Although the ISI component is forced to zero, there may be a chance that the equalizing filter will greatly enhancing the noise power and hence the error performance of the resulting receiver will still be poor. To see this, let us evaluate the signal-to-noise ratio at the output of the zero-forcing equalizer when the transmission filter ÀÌ ´ µ is fixed and the matched filter is used as the receiving filter, i.e., £ ÀÌ ´ µÀ £ ´ µ ÀÊ ´ µ (4.19) In this case, it is easy to see that the digital filter À ´Þ µ is given by À ¾Ì ½ ½ Ì Ò ½ ¬ ¬ ¬ ¬ Ò ¬¾ Ì ¬¬¬ Ò Ì À ÀÌ (4.20) and the PSD of the colored Gaussian noise samples Ò in Figure 4.11 is given by ¨Ò ¾Ì ¬ ...
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This note was uploaded on 12/13/2012 for the course EEL 6535 taught by Professor Shea during the Spring '08 term at University of Florida.

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