MMSE equalizer for ADSL

Hi everybody,

I'm trying to implement the MMSE algorithm for the Time Domain Equalizer
used in the ADSL communication.
I receive real ADSL data from an AFE. I can decode without error the data
used in the 994.1 ITU norm.
Now I'd like to equalize the upload channel with the training sequence
used in the 992.1 norm.
Presently I use the LMS algorithm to comput the equalizer taps.
The training sequence is generated like that:
- IFFT the PRU, after getting the 33 to 63 datas with the conjugate of the
1 to 31 PRU data
- convolution of the training sequence with the TIR (target Impulse
Response)

The transmission channel delay is obtain by crosscorrelation between the
received datas and the training sequence. The place of the max value of
the Xcorrelation vector gives me the delay.

then the equalizer taps are computed with the LMS algorithm (I use 30 taps
and µ=0.01)

the error obtained fall sometimes under 0.01, but the symbol obtained
after the FFT aren't the same of those obtained by making the FFT on the
training sequence

Could anyone tell me if I'm on the good way (if yes, what should I do to
make it work correctly) or if the equalization is made differently (If
yes, HOW???)

Thanks a lot!

Charly




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