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Re: [8023-10GEPON] Revised 10G budget



Dear All, 

Regarding the FEC selection - I agree that the FEC aspect is more of a
target than a fixed value.  However, we also can consider that the bare Rx
sensitivity is a 'soft value'.  It depends on a wide range of practical
concerns, such as yield, cost-effectiveness, technical innovation, etc. So,
in the end, all of these numbers are based on our best judgment at the
present time, integrating over all the variables in our minds.  

So, for the purposes of this baseline, I'd like the group to consider these
values as a 'global average,' and that they don't individually isolate each
element of technical risk.  Instead, by averaging, we can reduce the total
risk since it is unlikely that all the risks will line up against us.  

Also keep in mind that we can change them in future, if we really come up
against a hard problem.  The purpose of a baseline is to have a default
answer that everybody can really concentrate on, and effectively 'try to
shoot down'.  If it survives the onslaught, well then it must be good.  

For example, once we get this optical baseline set, the group's work will
turn towards the study of FEC codes and their realistic *optical* gain.
That will take some time, and in the end we will get our answer of how many
dB's we get.  We will likely then need to come back to the optical budget
and make some small adjustments based on our better understanding.  

On the issue of the PR20-D, I raised the maximum output power of the Tx
primarily to make the overload of the PR20 and PR10 receivers line up.  The
fact that this loosens the Tx spec seems harmless.  If manufacturers want to
make their Tx with better controls, then that is fine.  But, for purposes of
specification, this set of numbers just comes out with fewer 'loose ends'.  

If folks want to change that back to a 3dB range, I would not object too
much.  However, (in the spreadsheet) we will have to modify the Rx overload
to maintain commonality between the PR10 and PR20 classes of ONU (which I do
want to maintain).  Alternatively, we can decrease the minimum path loss in
the PR20 case by 1dB, which would also bring things in line.  

Sincerely,
Frank Effenberger


-----Original Message-----
From: Motoyuki TAKIZAWA [mailto:mtaki@ACCESS.FUJITSU.COM] 
Sent: Thursday, October 18, 2007 7:15 AM
To: STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: Re: [8023-10GEPON] Revised 10G budget

Dear Frank,

Thank you for the modification.
On the whole, it seems very sensible proposal except for some
items such as FEC selection etc.
Some questions on the PR20-D;

Could you explain why you've widened the launch power range from
3dB to 4dB only for PR20-D?
I just guess the reason like the following assumption.
- Margin
If we assume a cooled EML, 3dB would be safe enough.
Or maybe is it a margin for additional SOA variation?
- uncooled EML
Since EML+AMP is supposed to be the PR20-D basic transmitter,
EDFA output stabilization feedback can be utilized to reduce
variation range.
It is not clear whether 4dB range is sufficient or not for
an uncooled-EML with SOA.  And I am not sure the combination
of cooled SOA and uncooled EML makes sense.

Having 4dB range will be more comfortable but if there's no
special intention for that, 3dB range in line with other classes
may make sense.


Best regards,
Motoyuki Takizawa


On Mon, 8 Oct 2007 16:47:43 -0400
Frank Effenberger <feffenberger@HUAWEI.COM> wrote:

> Dear All, 
> 
>  
> 
> I have taken some of the comments I received on my last Email, and
modified
> the slides to come to the attached version.  
> 
>  
> 
> What I¡¯ve done is: 
> 
> 1.	Reduce the PR10 OLT downstream transmitter Max and Min by 1 dB.
> (This reverts to the values presented in Takizawa¡¯s slides in September)
> 2.	Reduce the PR10 ONU Rx overload number by 1 dB. (Following the Tx
> change)
> 3.	Increate the PR20 OLT max power by 1 dB (Makes the Tx range 4 dB,
> which is more comfortable)
> 4.	Increase the PR20 ONU Rx overload number by 1 dB.  (Following the Tx
> change)
> 
>  
> 
> Taken together, these changes then make the PR10 and PR20 ONUs identical
in
> every respect.  One less PMD! 
> 
> This is re-capped on the last slide. 
> 
>  
> 
> Sincerely,
> 
> Dr. Frank J. Effenberger      ¸¥À¼¿Ë °£·Ò²©¸ñ
> 
> Huawei Technologies USA
> 
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