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Hi Mike,
Thanks for preparing this, I think it’s useful to get the discussion started. I’ve reviewed and had some colleagues look at it as well. I have a number of concerns/suggestions that will hopefully be constructive for the discussion..
On p7 I think it’s worth pointing out the penalty target. It’s not necessary, but since OIF allocates 0.5dB combined penalty to Interchannel Xtalk and CD, this is a useful number to keep in mind.
On p8, you have a definition from OIF - it’s worth adding an explicit statement: Interchannel Crosstalk can not in & of itself determine the OSNR penalty. There’s a concern that this isn’t clear in what follows, and the actual penalty is tied to one Rx implementation.
The other concern here is that if we have a Crosstalk spec, it’s impossible to determine if it will be met by a link design without knowledge of the Tx spectrum. Since Interchannel Crosstalk from a link can not be calculated without defining the transmit spectrum, one should be defined. Based on what follows, we recommend using a RRC with a 0.4 roll-off as a reference spectrum for this calculation – subject to change when specs are adopted.
P9
Add CD, PMD in penalty. We’re wondering if this should also add a filter penalty? This says "include" so doesn't necessarily preclude these. However the full list should be included.
How to calculate the link penalty as a combination of impairments is a challenging issue.
P10
It’s unclear to me if measurement tolerances should be included here. Worth discussing.
P11-12
Should a spec be placed on the transfer function of the filters? Right now there is only a ripple spec. This should be discussed along with the reference spectrum.
The data is provided for a particular receiver. Details of crosstalk spectrum are important here.
OIF defines an 0.5dB penalty for -8dB Xtalk + CD penalty for their 100GHz spaced spec.
P15
Recommend removing 3dB point.
The -10dB data likely constrains the Tx Spectrum to an RRC spectrum with an 0.4 roll-off.
Filtering and Xtalk penalties should be included in selecting the maximum RRC spectrum. Is it worthwhile to base the specs on a particular spectrum such as RRC? This would seem to be useful for interop and to allow a single point to define the Tx spectrum.
P16
This is been modified since the first version of the presentation to change it to a baseband spec. This is a useful correction.
The spec that was in the last version of the presentation was removed. The previous spec was consistent with the OIF minimum excess BW. Since 802.3cw is moving to a tighter spacing, we may want to tighten the spec allowing a sharper roll-off.
P17-18
Tx Specs:
Missing Specs from OIF are a concern. My preference would have been to start with the full list of specs, and then remove those that we consider unnessary.
Laser Frequency Noise
Tx Clock Phase Noise (13.1.213)
These two are a major deviation from OIF.
OOB OSNR (13.1.231) – maybe not necessary to include.
I/Q Instantaneous offset -20 dB is included in OIF IA (13.1.270a)
• Is the Max I/Q Offset (-26dB) included equivalent to DC I/Q Offset in OIF IA (13.1.270a)?
A number of parameters have been omitted that I believe are intended to be included in EVM, but this is not stated:
• Mean I/Q Amplitude Imbalance
• I/Q Phase Imbalance
• I/Q Skew
We should clarify the specs that we are including in EVM, so we have something to point to when people are looking for them.
P19:
Spec for 50krad/s SOP Tolerance does not call out measurement conditions. OIF defined it @ max PDL/PMD relative to the same impairments at a 1krad/s rate.
Should add PDL to path penalty, unless the intention is to allocate a separate penalty for this.
Ripple should specify BW. We should discuss how to specify filter in the context of a black link.
P20: Rx should specify 20ppm
After reviewing this I feel like we need to take some time to address some of these issues before adopting a baseline.
Regards,
Mike,
I appreciate your efforts at driving this proposal forward, and will allow it in that interest.
However, please note any further changes that are more than editorial or adding participants will be subject to the approval of the Task Force before hearing.
All – please take the time between now and Thursday’s meeting to review and send comments / questions to the reflector, hopefully tomorrow. As we all know our calls are limited 2 hours, so getting discussions happening prior to the call is key.
And I will remind everyone that in my role as chair:
- The operation of the TF has to be balanced between democratic procedures that reflect the desires of the TF members and the TF Chair's responsibility to produce a draft standard, recommended practice, or guideline in a reasonable amount of time for review and approval by the WG. Robert's Rules of Order shall be used in combination with these operating rules to achieve this balance.
Please keep this in mind as we meet on Thursday.
Regards
John D’Ambrosia
Chair, IEEE P802.3cw Task Force
From: MICHAEL SLUYSKI <msluyski@xxxxxxxxxxx>
Sent: Tuesday, April 21, 2020 4:10 PM
To: STDS-802-3-DWDM@xxxxxxxxxxxxxxxxx
Subject: [802.3_DWDM] sluyski_cw_01_200416 proposed edits
Dear Colleagues,
I wanted to share a minor update to the baseline proposal that is posted on the .3cw website Slide . I will be asking John to allow this update before I present on Thursday. A group of us have been working together for a few months to ensure we are able to make progress in the .3cw Task Force. John posted this last week and I’m looking forward to getting wider feedback. I would appreciate if anyone has any comments or feedback on the proposal that we could start a discussion on the reflector or send to me directly.
And if anyone is interested in being included as a supporter let me know.
Mike A. Sluyski
System Consulting Engineer (SCE)
office 978.254.2773 | email: msluyski@xxxxxxxxxxxxxx
3 Mill and Main Place #400, Maynard, MA 01754
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