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Re: [10GBT] Proposed PAM8 vs. PAM12 resolution process



Hiroshi,

The residual noise power isn't just the background noise, but also includes
the alien NEXT power, the residual echo/NEXT/FEXT power etc. This is the
input-referred residual noise power that each system is withstanding at the
slicer.

Sailesh.

>From: hiroshi takatori <hiroshi.takatori@KEYEYE.NET>
>Reply-To: "IEEE P802.3an" <STDS-802-3-10GBT@listserv.ieee.org>
>To: STDS-802-3-10GBT@listserv.ieee.org
>Subject: Re: [10GBT] Proposed PAM8 vs. PAM12 resolution process
>Date: Sat, 17 Jul 2004 18:14:06 -0700
>
>Sailesh,
>I think all you are saying is that
>         i) $B!! (JBoth systems, PAM8 and PAM12 are showing roughly same
>noise margin with -150dBm/Hz BGN,
>         ii) -150dBm/Hz BGN is defined as spectral density, and
>         iii) PAM8 uses wider bandwidth than PAM12 by 17.5%,
>
>therefore, PAM8 is suffereing bigger BGN at input by 0.8dB (not 2dB as you
>presented) than PAM12.
>
>
>THIS IS NOT CORRECT!
>
>The tolerable external noise is identical for both systems. That is
>-150dBm/Hz! You can not convert this into rms value unless bandwidth is
>defined. The bandwidth is determined by the receiver itself. PAM8 needs
>more bandwidth than that of PAM12 which means that PAM8 is more sensitive
>to the higher frequency noise. What I am pointing out is that PAM12 rejects
>more noise than that can be rejected by PAM8.
>
>Plus, as we discussed back room in Portland hotel, PAM8 pollute more than
>PAM12 does. I will show you more in detail soon.
>
>I will take a look at default values in the matlab code and do more
>details. Do you prefer to have 0.75+0.25/Z in your PAM8 and compare with
>PAM12 without such filtering or just simple PAM8 and PAM12?
>
>Hiroshi Takatori
>KeyEye Communication
>
>
>
>-----Original Message-----
>From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
>Behalf Of Sailesh Rao
>Sent: Saturday, July 17, 2004 3:30 PM
>To: STDS-802-3-10GBT@listserv.ieee.org
>Subject: Re: [10GBT] Proposed PAM8 vs. PAM12 resolution process
>
>Hiroshi,
>
>The default cancellation parameters are in the matlab source code on the
>task force web site:
>
>http://grouper.ieee.org/groups/802/3/an/public/material/index.html
>
>As far as the transmit PSD is concerned, please feel free to send me
>what you think is optimum for the PAM12 system and I would be happy to
>use that. Please note that the matlab code currently uses a flat
>transmit PSD. However, I believe that the proposition before us, viz.,
>
>"When two PAM systems have roughly the same SNR margin
>(Margin(PAM8)=5.6dB,  Margin(PAM12)=5.9dB), the PAM system with the
>smaller number of levels (PAM8) will be fundamentally more robust
>towards external noise,"
>
>holds regardless of the transmit PSD. For instance, whatever transmit
>PSD is proposed for the PAM12 system, we can always scale that in
>amplitude and frequency and reuse it for the PAM8 system.
>
>Regards,
>Sailesh Rao
>srao@phyten.com
>
> >From: hiroshi takatori <hiroshi.takatori@KEYEYE.NET>
> >Reply-To: "IEEE P802.3an" <STDS-802-3-10GBT@listserv.ieee.org>
> >To: STDS-802-3-10GBT@listserv.ieee.org
> >Subject: Re: [10GBT] Proposed PAM8 vs. PAM12 resolution process
> >Date: Fri, 16 Jul 2004 23:09:07 -0700
> >
> >Sailesh,
> >
> >Please, define default cancellation parameters and necessary parameters
> >to create transmit PSDs for both PAM8 and 12.
> >
> >Hiroshi
> >
> >KeyEye
> >
> >________________________________
> >
> >From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
> >Behalf Of Sailesh Rao
> >Sent: Friday, July 16, 2004 9:01 PM
> >To: STDS-802-3-10GBT@listserv.ieee.org
> >Subject: [10GBT] Proposed PAM8 vs. PAM12 resolution process
> >
> >
> >
> >All,
> >
> >
> >
> >I would like to propose the following process for resolving the
> >robustness of PAM8 vs. PAM12 towards external noise.
> >
> >
> >
> >1. Compute the Optimum DFE SNR Margin for PAM8 and PAM12 using
> >solarsep_varlen7a.m for Models 1 and 3 using default cancellation
> >parameters and -150dBm/Hz background noise.
> >
> >
> >
> >2. Compute the input-referred RMS noise power at the slicer by
> >integrating the residual noise in the Optimum DFE solution. I volunteer
> >to add this code to solarsep_varlen7a.m unless someone else wants to do
> >so.
> >
> >
> >
> >3. Compute the input-referred external noise power that can be
>tolerated
> >for a BER of 1E-12 for both systems using the results from (1) and (2)
> >above. I volunteer to add this code to solarsep_varlen7a.m unless
> >someone else wants to do so.
> >
> >
> >
> >Regards,
> >
> >Sailesh Rao.
> >
>
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