Re: [8023-10GEPON] [FEC Superating] - kickoff preso
Dear Frank,
This is indeed a very interesting and well written presentation. I enjoyed it in terms of the description of the problem as well as questions it raises.
I agree with You that "when you stack up the pros and cons, these two schemes are pretty equal" and that the best way out of it is to run the economic assessment for both aforementioned scenarios.
Super rating seems more appropriate for marketing reasons since the subscribers do get 10G data channel, which is FEC protected via increasing the effective data rate to compensate for the additional overhead. We must however remember that the data rate increase to 11.09 Gbit/s may cause increase in the overal system cost since at least the PMDs have to run at this data rate. From the definition point of view, that is no problem to achieve but then You have to make sure that the component cost will not be suddently 20-30% higher since this is not a standard data rate for Ethernet equipment ... I would say that we can live with the 0.3-0.4 dB sensitivity penalty and we can include that in the spreadhseet we work on.
As for th subrating, it seems more technically balanced, since we can reuse large parts of what has been done so far and simply use IPG stretching when necessary. The 7% loss in the effective bandwidth means that 1-2 ONUs less can be connected effectively in the system, which is a constant loss for the service provider.
I am not certain but it seems to me that it would be easier to justify the superrating than subrating, at least from the economic point of view. Technical issues are another thing, though someone may disagree and say that it is easily resolved ...
Best wishes
Marek Hajduczenia (141238)
SIEMENS Networks S.A. - IC COM D1 R
Rua Irmãos Siemens, 1
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2720-093 Amadora
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* Marek.Hajduczenia@siemens.com
http://marekhaj.easyisp.pl/index.php
(+351.21.416.7472 4+351.21.424.2082
-----Original Message-----
From: Frank Effenberger [mailto:feffenberger@HUAWEI.COM]
Sent: quarta-feira, 31 de Janeiro de 2007 20:32
To: STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: [8023-10GEPON] [FEC Superating] - kickoff preso
Dear All,
I have put together the following presentation on the issue of FEC and
line-rate vs. MAC-rate modification. I tried to include in these slides all
the arguments I have heard favoring one method or the other. If I have
forgotten your favorite, you can shoot an Email to me, and I'll add it to
the list.
You may also note that the last slide, entitled "Reaching a decision" is
blank. I don't know a truly objective way to solve this problem... It seems
to me that when you stack up the pros and cons, these two schemes are pretty
equal.
One last thought: The one 'hard' (objective) con for the super-rating scheme
is the loss of 0.3 dB of sensitivity. The one 'hard' con for the sub-rating
scheme is the loss of bandwidth (7% lost). How can we put these two items
on a common comparative base? Usually, the common denominator in these
situations is cost, so...
What is the relative system cost increase due to 0.3dB optical loss?
What is the relative system cost increase due to a 7% capacity loss?
If someone wants to hazard an answer to these questions, please do.
Regards,
Frank E.