Re: [10GBT] Summary of issues with PAM12
Oops.
> -----Original Message-----
> From: Jonathan Thatcher [mailto:jonathan.thatcher@ieee.org]
> Sent: Thursday, August 19, 2004 8:54 AM
> To: 'IEEE P802.3an'
> Subject: RE: [10GBT] Summary of issues with PAM12
>
>
> Hugh,
>
> You are only person on copy.
>
> I've been thinking about you point below and wondering the
> same. I can think of two reasons why a detractor of PAM-12
> might care about the technical proposal for PAM-12. First,
> they are engineers. Need I say more? More importantly, they
> might be considering the possibility that this is a Trojan
> horse. That is to say that once PAM-12 is adopted, and it is
> discovered that it is really hard, a more efficient PAM-12
> constellation is introduced. Presuming that said
> constellation will be more difficult to implement and have
> negative impacts (e.g. number of cells, power, latency...)
> and that if it had been introduced prior to the adoption of
> the PAM-12 proposal it would have been rejected out of hand,
> it would live only because of deception (or incompetence, you pick).
>
> All of this is purely speculation, of course. I can imagine
> that PAM-12 detractors would not want to directly raise this
> issue in a public forum as it would seem at least politically
> incorrect if not outright accusatory.
>
> jonathan
>
> > -----Original Message-----
> > From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG]On
> > Behalf Of Hugh Barrass
> > Sent: Wednesday, August 18, 2004 9:42 AM
> > To: STDS-802-3-10GBT@listserv.ieee.org
> > Subject: Re: [10GBT] Summary of issues with PAM12
> >
> >
> > Hal,
> >
> > I don't understand why the "hole in the constellation" is seen as an
> > issue. It causes the PAM-12 to be less "efficient" than it could be,
> > just like the padding bits and encapsulation overhead. The
> > net result is
> > that the proposal using PAM-12 needs a symbol rate of
> 825Mbaud where a
> > lower clock rate might be used if the efficiency was better.
> > However, if
> > the comparison is made using that proposal and PAM-12 still
> comes out
> > better then perhaps the "inefficiency" is acceptable. If,
> on the other
> > hand and as Sailesh maintains, the comparison comes out in favor of
> > PAM-8 then the PAM-12 proponents might want to look at ways
> > of "trimming
> > the fat."
> >
> > It would be equally valid to raise the "issue with PAM-8"
> of "only 12
> > bits/baud" and require the PAM-8 fans to address that...
> >
> > Personally, I think 10GBASE-T would be best addressed by 4
> > pair, bonded,
> > 2BASE-TL on steroids :-)
> >
> > Hugh.
> >
> >
> >
> > Roberts, Hal wrote:
> >
> > >All,
> > >
> > >Sailesh provides a nice compact list of (his) issues with
> > regard to PAM12. I
> > >have seen responses to some of these but nothing addressing
> > or summarizing
> > >them all.
> > >
> > >In addition it would be useful (at least to me) to see a
> > similar summary of
> > >"Issues with PAM8" from a PAM12 proponent. (Unless based
> on Sailesh's
> > >criticisms there are no longer any PAM12 proponents? ;-)
> > >
> > >Finally, Sailesh has a good point that a number of his
> > issues have been
> > >completely unanswered. I am surprised no one has addressed
> > the 'hole in
> > >constellation' issue.
> > >
> > >
> > >
> > >
> >
>