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Dear Eric,
Yes, your understanding is correct: “the original version of slide 12 is plotting CD+FWM penalty, but the text and X axis referring to FWM only were incorrect”, which is a key reason we updated that figure.
Also, we are in good agreement that “it's worth more study” regarding the extinction ratio (ER). The ER we typically used in simulations is 6dB, as stated in some of the slides in our earlier contribution “liu_3df_01b_2207”. At ER=6dB, an AOP (average optical power) of +5dBm corresponds to an OMA of +5.8dBm (which is relatively high). Going forward, we can adjust the ER and OMA values based on their ranges that are to be specified in the margin allocation table.
Hope the above is helpful.
Best regards,
Xiang
From: Eric Maniloff [mailto:eric.maniloff.ieee@xxxxxxxxx]
Sent: Tuesday, October 18, 2022 5:12 PM
To: Liu Xiang (A) <xiang.john.liu@xxxxxxxxxx>
Cc: STDS-802-3-B400G-OPTX@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_B400G_OPTX] Clarification Request: Optical Specs in Xiang Liu contribution
Hi Xiang,
Thanks for the clarifications. The change in what's plotted in the new version on slide 12 definitely helps explain some of the difference. So if I'm understanding correctly, the original version of slide 12 is plotting CD+FWM penalty, but the text and X axis referring to FWM only were incorrect, yes?
Regarding the extinction ratio, I agree it's worth more study, but what value is used in the analysis? It's important to understand this to put the data in context.
Thanks, Eric
On Thu, Oct 13, 2022 at 1:19 PM Liu Xiang (A) <xiang.john.liu@xxxxxxxxxx> wrote:
Dear Eric,
Thanks a lot for your interest in the details of our contribution! Please find below the key points for addressing your question.
(1) Yes, the key update is on slide 12, where in the initial “01 version”, we stated “Note that when the highest signal launch power is limited to +4dBm per channel, the FWM penalty can be limited to 1dB for a relatively low outage probability of <1% (even under the worst-case alignment of ZDF and channel center frequencies).” At the time of the “01 version”, we did not have enough PMD realizations to see how much below 1% we can get.
(2) Based on valuable comments from some members of our task force, in order to be more conservative in margin allocation and more accurate in outage probability assessment, we increased the signal launch power per channel from 4dBm to 5dBm and conducted extensive simulations of over 2800 runs (to assess the outage probability down to ~0.1%), and produced the new figure on slide 12 of the updated “01a version”.
(3) Also, the previous figure on slide 12 of the “01 version” plotted the “combined CD+FWM” penalties instead of the FWM penalties alone (as specified by the x-axis label), and used 6dBm/6dBm/6dBm/3dBm for the four channels (as stated in the subtitle). To match the figure with the new statement, we replaced the figure with the updated one shown in the “01a version”.
(4) As I stated in the meeting yesterday when replying your comments, the power used here is AOP (average optical power launched into the fiber), whose relationship with the OMA depends on the ER. More studies with different ER values can be conducted as the margin allocation table specifications become more mature.
As you can see now, all the statements made in both versions are consistent. The update is made to better match the figure on slide 12 with the current working view of the power level used on the margin allocation table shown in rodes_3df_01a_221012. As also said when replying your comments at the meeting yesterday, we will continue our feasibility study based on further inputs from our Task Force.
Hope the above is helpful, and we look forward to working with you and other experts in our Task Force to keep refining the margin allocation table for 800G-LR4. Thanks again!
Best regards,
Xiang (on behalf of the co-authors of “liu_3df_01a_221012”)
From: Eric Maniloff [mailto:eric.maniloff.ieee@xxxxxxxxx]
Sent: Thursday, October 13, 2022 10:35 AM
To: STDS-802-3-B400G-OPTX@xxxxxxxxxxxxxxxxx
Subject: [802.3_B400G_OPTX] Clarification Request: Optical Specs in Xiang Liu contribution
Dear 802.3df Optical,
During yesterday’s presentations, I noticed that the power levels, analysis, and conclusion in Xiang Liu’s contribution had changed from last week’s version until yesterday’s:
https://www.ieee802.org/3/df/public/22_10/22_1012/liu_3df_01_221012.pdf#page=12
https://www.ieee802.org/3/df/public/22_10/22_1012/liu_3df_01a_221012.pdf#page=12
The net result was a change from a power limit of +4dBm for a 1dB FWM penalty to +5dBm for the same penalty.
Can we get a summary of the changes between the contributions, and the reasons for the changes? I see the analysis is changed, is the original analysis and conclusion still valid?
In addition, as mentioned on the call it would be worth specifying the exact power assumptions. I’m guessing that the powers are Average Power, not OMA. Knowing both the Average Power and Extinction Ratio is important. What are the specific power assumptions?
There are a lot of co-authors on this contribution, so any of them are invited to help clarify details and changes.
Regards, Eric
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