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From: cincydsp on 4 May 2008 23:24
On May 3, 6:13 pm, "despite" <han...(a)gmail.com> wrote:
> Hi,
> Maybe I could not put what I wanted to ask into correct words.
>
> ZF equalizer tries to minimize ISI and MS equalizer tries to minimize the
> difference btw desired signal and equalizer output.
>
> Where I am confused or lacking clue is the adaptive algorithm part.
>
> From your answer I understood that regardless of coefficient update
> implementation, the adaptive algorithms try to minimize difference btw
> desired signal and equalizer output but if there is no noise, they converge
> to ZF equalizer because this difference will only be due to ISI.Is this
> correct?
>

As Manolis pointed out, this is correct. The frequency response of a
zero-forcing equalizer is equivalent to that of a linear minimum mean-
squared error (LMMSE) equalizer when the signal-to-noise ratio is
infinite (i.e. there is only ISI, and no noise). The LMS algorithm
iterates toward these solutions by attempting to minimize the mean-
squared error between the filter output and the desired signal. This
is inherent in the development of the LMS algorithm, as it is a
stochastic gradient technique that "searches" for the coefficients of
the Wiener filter (i.e. the one that is optimal and actually minimizes
the MSE). So, I don't think your peak-distortion criterion is directly
applicable to an LMS implementation.

Jason
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