Re: [10GBT] Issues with solarsep_varlen7a.m
This matlab code has many options and switches and I'm not sure that I
can verify the integrity of all my corrections and publish the modified code
prior to the plenary meeting, next week. In any case, I am more partial to
the straight-forward MMSE pulse analysis code that we used and
published in the IEEE 802.3ab task force since it results in a more
comparison of the merits of one approach over another.
>From: SAMIR THOSANI <firstname.lastname@example.org>
>Reply-To: SAMIR THOSANI <email@example.com>
>Subject: Re: [10GBT] Issues with solarsep_varlen7a.m
>Date: Wed, 7 Jul 2004 12:42:37 -0700
>Thanks for providing this information. We've had always some doubts abt
>program. Can u please provide a modified code, so that we can have a look
>that before the meeting?
>----- Original Message -----
>From: "sailesh rao" <sailesh_rao@HOTMAIL.COM>
>Sent: Wednesday, July 07, 2004 12:33 PM
>Subject: [10GBT] Issues with solarsep_varlen7a.m
> > George/Carlos,
> > I would like to bring up some issues with the solarsep_varlen7a.m matlab
> > code that is found on
> > http://grouper.ieee.org/groups/802/3/an/public/material/index.html
> > I believe that these issues alter the conclusions that one could derive
> > this code.
> > 1. Frequency Base:
> > The frequency base for the DFE margin calculations is being inferred
> > the first column in the Insertion Loss files found in this directory. As
> > result, the frequency base ranges from 0 to 650MHz in all cases.
> > the average power P is being distributed evenly over (line 391)
> > bwmhz=1250MHz for the 2-bit PAM system,
> > bwmhz=1000MHz for the 2.5-bit PAM system,
> > bwmhz=833MHz for the 3-bit PAM system
> > This means that 48% of the input power is unused in the 2-bit system,
> > unused in the 2.5-bit system and only 22% is unused in the 3-bit system.
> > This tips the scale in favor of the 3-bit PAM system.
> > 2. Folded SNR calculation:
> > The folded SNR calculations in lines 443, 453 and 463 are not right. If
> > and f2 are mirror frequencies about fs/2, the formula being used is
> > S/N = ABS(S1/N1) + ABS(S2/N2) ;
> > However, the actual SNR at the folded frequency would be
> > S/N = ABS(S1+S2)/ABS(N1+N2)
> > where S1, S2, N1, and N2 are complex phasors. Therefore, in the context
> > folding, the actual PSD of the signal becomes relevant, whereas the
> > Salz formula for the optimum DFE SNR is independent of the PSD.
> > As done in the matlab code, this calculation also tips the scale in
> > the 3-bit PAM system since signal power is assumed to be zero for
> > due to (1) above.
> > 3. SNR Requirement for 1E-12 BER
> > The SNR requirement for 2.5bit PAM is 3.01dB worse than the SNR
> > for 2-bit PAM.
> > The SNR requirement for 3bit PAM is 6.23dB worse than the SNR
> > for 2-bit PAM.
> > The code is using 2.95dB and 5.94dB respectively in lines 446, 456 and
> > which also tips the scale in favor of the 3-bit PAM system.
> > Regards,
> > Sailesh Rao.
> > _________________________________________________________________
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