Re: [8023-10GEPON] [FEC Superating] - kickoff preso
Frank hi,
Loop-timing for the asymmetric 10/1 case would appear to be another "pro" for the subrating scheme.
The ONU can - perhaps - use the recovered 10.3125 clock to derive one of 312.5 Mhz (divide by 33), and then use a PLL to generate the upstream rate (multiply by 4). With 11.1 Gb/s XSBI this would probably be much more difficult.
- Jeff
-----Original Message-----
From: Frank Effenberger [mailto:feffenberger@HUAWEI.COM]
Sent: Wednesday, January 31, 2007 10:32 PM
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.