Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

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



Alon,

And to check the relative attenuation, we compute the  unit pulse response
at the input of the receiver for the two PAM systems...

Congratulations on completing the full circle :-).

Regards,
Sailesh Rao.

>From: "Meisler, Alon" <alon.meisler@INTEL.COM>
>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: Sun, 18 Jul 2004 17:25:28 +0300
>
>But...
>
>Since the PAM 8 will be more attenuated at the receiver, scaling it by
>the AGC, will turn the apples (PAM 8 external noise) to cantaloupes (PAM
>12 size). Don't you think, Sailesh?
>
>It won't do the same for a noise that is generated after the AGC, say in
>the ADC. Hence - internal...
>
>Alon
>
>-----Original Message-----
>From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
>Behalf Of sailesh rao
>Sent: Sunday, July 18, 2004 4:58 PM
>To: STDS-802-3-10GBT@listserv.ieee.org
>Subject: Re: [10GBT] Proposed PAM8 vs. PAM12 resolution process
>
>Hiroshi,
>
>I agree with you that it only matters how robust the receiver is against
>"EXTERNAL NOISE". The only reason for me to compute the input-referred
>"INTERNAL NOISE" power in the proposed comparison is to compute what the
>5.6dB/5.9dB SNR margins for PAM8/PAM12 really mean in terms of raw
>external
>noise tolerance.
>
>My point is that when we speak of SNR margins for PAM8 and PAM12, we are
>actually comparing apples (PAM12) to cantaloupes (PAM8).
>
>During EMI compliance tests, we are not going to be using worst-case
>impairments in the cabling setup, and it would be advantageous for us to
>have several cantaloupes worth of external noise tolerance (PAM8) as
>opposed
>to several apples worth (PAM12).
>
>Regards,
>Sailesh Rao.
>
> >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 22:16:30 -0700
> >
> >Sailesh,
> >Sailesh,
> >
> >It only matters how robust the receiver is against "EXTERNAL NOISE".
> >Do not confuse how robust the receiver against "INTERNAL NOISE". When I
> >said "INTERNAL NOISE" it includes all IC implementation losses due to
> >any non-ideal devices such as ADC, DAC, jitter, analog circuit
>linearity
> >and others.
> >When we discuss PAM8 and 12 comparisons, it should be focused on which
> >solution performs better with ideal conditions, meaning no
> >implementation loss. This tells which solution is fundamentally better
> >in theory and this has to be done first.
> >
> >You showed in your presentation PAM12 performs better in models 1, 3,
> >and 4 when BGN is -150dBm. This means that with very small
> >implementation losses, PAM12 performs better than PAM8 over the long
> >cable. I agree that and also I agree that PAM8 is better than or as
>good
> >as PAM12 for model 2, which is 55m case.
> >
> >It is true that all IEEE folks want to know if it can be practically
> >implemented or not. When we argue the comparison with the
>implementation
> >losses, the argument will be very muddy because it changes many things
> >depending on which criteria we use, power and complexity with the
> >function of technology assumption in time. Therefore, KeyEye's approach
> >has been the comparison with the define BGN -140dBm/Hz as the
> >implementation loss.
> >
> >In summary,
> >         1. We all agree PAM12 is better in theory or with very small
> >implementation loss for 100m cable.
> >         2. We all agree PAM8 and 12 will be performing about same for
> >55m cable.
> >         3. If we need to argue more on the comparison with the
> >implementation loss, I propose to define BGN such as -140dBm/Hz as the
> >implementation loss and then compare PAM8 and PAM12.
> >
> >
> >Hiroshi Takatori
> >Keyeye Communications, Inc.
> >
> >
> >-----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 7:01 PM
> >To: STDS-802-3-10GBT@listserv.ieee.org
> >Subject: 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.
> > > >
> > >
> > >_________________________________________________________________
> > >Overwhelmed by debt? Find out how to 'Dig Yourself Out of Debt' from
> >MSN
> > >
> > >Money. http://special.msn.com/money/0407debt.armx
> >
> >_________________________________________________________________
> >Planning a family vacation? Check out the MSN Family Travel guide!
> >http://dollar.msn.com
>
>_________________________________________________________________
>Discover the best of the best at MSN Luxury Living.
>http://lexus.msn.com/

_________________________________________________________________
MSN Toolbar provides one-click access to Hotmail from any Web page  FREE
download! http://toolbar.msn.click-url.com/go/onm00200413ave/direct/01/