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Re: [802.3_100GNGOPTX] SMF Ad Hoc and MMF Ad Hoc rescheduled



Jonathan

Lets look at sample example assuming 25.78 GBd operation for a laser with Teff=24 ps, with DCD=4.28 ps.

B= 1/(1/25.78 - DCD/1000) =28.74 GBd would be the effective bitrate

The current spreadsheet predicates if  DCD (the intention here was DDPWS)  increases then effective bitrate increases 
as expected the ISI penalty should but not the MPN and cross penalty!  

What I suggest to use for B for calculation of MPN and Cross is the 
B1= 0.35/Teff = 14.5 GHz instead of 28.977 GHz.

If you take 10G VCSEL and operate it at 25.78 GBd, will the MPN increase? At first order the answer is no, only the ISI should 
increase otherwise you are double counting the penalty.   When I use B1=14.5 GHz then the MPN goes from 0.4 to 0.03 dBo
and Pcross goes from 5.38 to 1.69 dBo at 115 m of OM3 just before the spreadsheet blows up.

Thanks,
Ali

On Feb 16, 2012, at 11:02 AM, Jonathan King wrote:

Hi Ali
Thanks for your e-mail - the statement to note recent work in T.11 is just that – we should take note of the work  and look at what the consequences are for Ethernet rates.
 
My understanding of the spreadsheet is that the MPN penalty is counted just once: the average effect of chromatic dispersion for a multimode source with a given rms spectral width is included in the ISI penalty;  the MPN term just accounts for the noise term due to power moving around between laser modes.  Can you explain what you mean by double counting ?
 
Thanks
jonathan
 
From: Ali Ghiasi [mailto:aghiasi@xxxxxxxxxxxx] 
Sent: Thursday, February 16, 2012 9:58 AM
To: Jonathan King
Cc: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SMF Ad Hoc and MMF Ad Hoc rescheduled
 
Jonathan
 
In regard to statement given in your presentation, I like to add some more color to this statement
     Note: recent work on MPN treatment, by David Cunningham, shown in T11 (Fibre Channel), indicates that FEC is a necessity for 100m links
 
32GFC operates at 28.05 GBd, current spreadsheet model do show very steep increase in penalty as result of mode partition noise and cross terms.
The FC group wants to support 100 m on OM4 fiber, with current noise model even with a simple FFE EQ FEC would be required to close the link
budget.  Also the same spreadsheet shows that if we added FEC with overhead and operated at 28 GBd instead of 25.78 with 2.5 dBo or 5 dBe penalty 
we could be worse off than using FEC.  So our only option would be to use inband FEC which has higher latency.
 
With 100GNGOPTX investigating 2nd generation set of PMD where there already exist set of solution, as a group we have to deliver a solution 
which allow seamless migration from 40G-SR4 and is lower cost than 100G-SR10.   If it requires fundamental investigation then the group need
to undertake it!
 
My concern with current spreadsheet model which I have also shared with David Cunningham is how B (bandwidth) is used for calculation of MPN,
for mode partition noise and the cross term for detail analysis please see David presentation 
 
B= 1/(T-DCD) where T is the 1/Baudrate 
 
â=π.B.D.L.σλ
 
σmpn = kOMA/√2 . [1 - e^(-β^2)]
 
I do agree in the ISI calculation we should use DCD to increase the effective baudrate but if 
you have slow laser which is the case for 25.78 operation both ISI and MPN do not increase 
the laser is toggling faster but never reaches steady state!  The spreadsheet already captures 
the ISI penalty and double counting might have been negligible at lower speed when the 
laser were fast but double counting at these speed breaks the link or we end up with a link 
significantly shorter!
 
What seems reasonable here is to use the current B for ISI penalty calculation but for MPN and Cross
use the following 
B1= 0.35/(Teff)
where Teff is the RMS mean of sqrt(Trise^2+Tfall^2/2) as I expect current Ts is in the spreadsheet 
is the Tfall time.
 
Thanks,
Ali
 
 
On Feb 13, 2012, at 5:52 PM, Jonathan King wrote:


Dear all,
Here is my presentation for the MMF ad hoc call , 14th Feb 2012
This is intended to be an introduction to, and framework for, discussion on what we do as an ad hoc to progress towards an MMF objective.
Best wishes
jonathan
 
 
From: Anslow, Peter [mailto:panslow@xxxxxxxxx] 
Sent: Friday, February 10, 2012 3:48 PM
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: [802.3_100GNGOPTX] SMF Ad Hoc and MMF Ad Hoc rescheduled
 
Hi,
 
By popular request, we have moved this meeting to Tuesday 14 February at the same time as before. (With apologies to Paul who now can’t attend.)
 
Hi,
 
As mentioned by Dan, Jonathan and I are planning to hold an SMF Ad Hoc meeting immediately followed by an MMF Ad Hoc meeting (1 hour each) starting at 8:00 am Pacific on Tuesday 14February.
 
Peter Anslow from Ciena has invited you to join a meeting on the Web, using WebEx. Please join the meeting 5-10 minutes early so we may begin on time. 

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Topic: "SMF Ad Hoc followed by MMF Ad Hoc" 

Date & Time: Tuesday, 14 February 2012 at 16:00, GMT Time (London, GMT) 

To join web meeting click here: https://ciena.webex.com/ciena/j.php?ED=136397587&UID=0&PW=NZGZiMTQ2OTgw&RT=MTgjMjE%3D 

Meeting password: IEEE (please note passwords are case sensitive) 

Teleconference: Call-in number: +44-203-4333547  (United Kingdom) 
Conference Code: 207 012 5535 

Meeting number: 681 000 052 

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Additional Notes: 

- To add this meeting to your calendar program click the following link, or copy the link and paste it into your Web browser: https://ciena.webex.com/ciena/j.php?ED=136397587&UID=0&ICS=MI&LD=1&RD=18&ST=1&SHA2=amYBeqds-4oJeKBgc6O4QfHGLLIvaO7ruJQoBj-3bY0=&RT=MTgjMjE%3D 

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Regards,
Pete Anslow | Senior Standards Advisor
43-51 Worship Street | London, EC2A 2DX, UK
Direct +44 2070 125535 
|
 
From: Daniel Dove [mailto:ddove@xxxxxxx] 
Sent: 09 February 2012 17:37
To: STDS-802-3-100GNGOPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_100GNGOPTX] SG Phase - Critters and Objectives
 

John, Steve;

Thanks for this contribution to the forward progress of the Study Group.

I would like to ask that our participants take the time to open the links below and refresh themselves on these points.

In my experience, the tendency for a Study Group to get distracted is not new, and the need to continually remind ourselves of where we are in the process is essential.

I would add that each project has its own unique characteristics and therefore the process provides boundaries but the path will always be slightly different. Given that we (100G Ethernet) have optical PMDs which already exist and satisfy broad market potential, it changes the relative importance of the 5 criteria responses. We are not just comparing ourselves to prior speeds or other media types, but to 100G PMDs that are currently available. We need to be distinct, economically feasible against those alternatives in order to meet the needs of a broad market, and demonstrate we are technically feasible as well.

Your advice is appreciated and we should all be diligent to remain within the process boundaries and seek a path that brings us to a successful PAR and 5 criteria response. In that regard, focus on the process is essential. 

Jonathan and Pete are in the process of setting up a co-joined adhoc meeting that will address objectives and 5C responses for both the MMF and SMF technologies. We hope to provide that focus, and define a path for forward progress.

Best Regards,

Dan

<MMF-objective-Next-Steps.pptx>