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The EDC assumptions used for LRM (10G) development was that the dispersion effect is linear. (ie every one or zero is identical and the eye closure is created because the bit energy is not confined within one bit period and smears out over multiple pulses such that with superposition of the bits the eye closes. ie it's linear ISI that is being compensated.). It also assumes that the ones and zeros are inverts of each other. I think the problem for 1550nm DML is likely to be chirp. Does anyone know if chirp has this deterministic linear characterisitic and whether the ones and zeros are inverts of each other. (I don't think they are).
I'm not suggesting that EDC can't help. I am suggesting that a more complicated version of EDC might be needed than that assumed for LRM, and the benefits achieved might not be as great as initially expected.
From: Roger Merel [mailto:rmerel@GMAIL.COM]
Sent: Friday, December 22, 2006 1:16 PM
Subject: Re: [HSSG] <HSSG-FO> Fiber Optic Ad Hoc Teleconference 12/18/2006
To the extent that dispersion penalties adversely affect the link budget (even if the link works) for 1550nm 10G (or 20G/25G) using DMLs, one can consider using EDC to reclaim some of those penalties. EDC at 10G is readily available, but yet not presently available at 20/25G.
I would like to propose the change of Reach (Technical) Feasibility Table what Chris created.
Please see attached file.
We confirmed that 1550nm DML is possible to support 10G-10km/40km.
Also, it might be possible to support 20G/25G-10km if only dispersion penalty is a bottleneck.
My proposed change is as follows.
1) 10km, 1550nm, 10G DML: change to “yes” from “maybe”
2) 40km, 1550nm, 10G DML: change to “yes” or “maybe” from “no”
3) 10km, 1550nm, 20G/25G DML: change to “maybe” from “no”
Any comments are welcomed for me.
Have a happy holiday!
Vice president of Engineering and Marketing
Excelight Communications (A Sumitomo Electric Company)
We held our teleconference this morning but unfortunately, the bridge supplier I use had changed their PIN system and I was forced to send out a new bridge number at the last minute. I realize some people were unable to attend due to this occurrance, and I give you my apologies.
I am going to provide the meeting notes below. If you see any need for correction to the notes, please send an email to firstname.lastname@example.org and I will update the minutes before posting them on the HSSG-FOAH website. This will prevent multiple messages with corrections being sent onto the reflector, OK?
Also, for all who are interested, I am calling for presentations at the January Interim. Those presentations should be specific to proving technical and economic feasibility for a single-mode 10Km link, and for a 100m multi-mode link. It is important to recognize that we are not trying to select a specific proposal at this time, but to demonstrate to > 75% of the HSSG and IEEE 802.3 that we have proven these things.
Today's work was focused on single-mode only, so we should be sure to get multi-mode presentations on the table as well.
Chairman, HSSG FO Adhoc
Discussed the new table additions and corrections made since last teleconference;
Discussed Chris Cole Presentation;
Matt: Discrete devices available, extrapolation not necessarily valid
For example, EMLs tend to be larger, take up more wafer space
Chris: Another thing not captured, 10G DML @ 1550 not considered in green but maybe we should take it off the study list because hard to build as monolithic array
Xaviar: Would like to avoid taking things off at this point. Would like to present work showing it’s a viable alternative.
Chris: DML at 1550 gonna work at 40k?
Mike D: CWDM being considered for all or just 1310?
Chris: Does not address this distinction. Slide 4 addresses some of this, but slide 3 is trying to capture wavelength and transmitter type. This table does not capture "optimum" or "implementation complexity".
Chris discusses his perspective. Nobody argued with his position that 20G 10K DML not possible.
General: Would be nice to have 40K and 10K leverage common approach. Green applied where it appears to be possible.
Marc Lucent: Main objective regarding DQPSK at 50 / 1310 is dispersion?
Chris: Yes, the implementation for 50G 1550 looks large and therefore does not seem LAN oriented. At 1310 makes better sense.
Marc: For 40Km, 1550, might make better sense for this longer reach.
Chris: Yes, the breakpoints for 10G are 1310 DML and 1550 EML, so this is consistent. For us, its possible to set the breakpoint at 40-80Km. Question is, do we really want to add the cost of this technology for 40Km.
Marc: Chromatic dispersion your primary concern?
Chris: Looking forward to presentations on this subject.
Robert Lingle: Main Point to have a pluggable in a small form factor and dispersion compensation may prohibit this.
Peter: Do you see an activity to standardize a form factor for a module?
Chris: yes. Likely done outside IEEE.
Peter: Would larger group oppose having different form factors?
Matt: With regard to 20/25G DML, been looking at 1310…wonder, at 10K, what were the dispersion numbers that led you to your conclusion?
Dan: My notes missed some of the content on this part..it was pretty dense..sorry;
Chris: Is there a breakpoint between 20G and 25G on DML?
Chris: Could provide an EML spec as long as it was possible to reduce cost in future.
Frank: We are dealing with tech feasibility, we need to consider cost too. For example, with 25G, you cannot do arrays, it creates a big cost issue.
Chris: yes, this is accurate. We need an economic feasibility table.
Discussion of page 4:
Copying conclusions from page 3 and modified format to make things more visible;
Why did 1550 get eliminated? Concluded DMLs in the timeframe not feasible due to dispersion.
This conclusion has been challenged and presentations may come in to address that.
For EML 20G 40Km is not leveragable.
Matt: Agrees with earlier comment to allow for 1st gen to focus on EML with longterm DML targets… maybe able to collapse rows 2,3 and 4,5 together.
Chris: Would be good to come up with an approach that allows this to happen.
Chris: We can add to the format additional proposals per email and discussion.
Mike: Is the intent of the cooling and grid columns to be 1 for 1 across?
Chris: If no cooling, drift will be larger and thus they should be cited independently.
Chris: Semi-cooling is less precise than cooling, but offers a lower cost means..for example heating to ensure minimum temps are eliminated.
No more comments on presentation. Some discussion on the upcoming meeting and it was stated by the chair that we should build presentations for January's interim rather than divide our attention on another phone conference.