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Re: [802.3_OMEGA] Baseline test for IEEE 802.3cz PMD/MDI

Dear all,

I agree the optical return loss tolerance of the TX needs to be defined. RIN is always influenced 
by reflections in general that arrive to the VCSEL device. The TX tolerance depends of the VCSEL 
device design but it is also very important how the optical coupling element (e.g. lens) between VCSEL
and fiber MDI is designed.

We have to define RIN_oma_x, where x is the return loss tolerance and the experimental setup adjustment requires specification of value x (in dB). 

I understood that TBD in the text of the contribution is not indicating that reflection does not need to be specified.

In many contributions done in OMEGA different connector types have been considered. Different connectors and different MDIs
will have different return loss properties.
I believe we should decide the TX optical return loss tolerance based on real experimental data or math models
of the connectors under consideration. Perhaps return loss tolerance of 12 dB is OK, or finally it results to be higher or lower for this application.

the RINoma = -124 dB/Hz with BWn = 20.9 GHz for 25 Gb/s link budget analysis. It is 4 dB higher than the RINoma levels considered in 802.3 PHYs. 

This RINoma specification relax in simulation is intended to facilitate the selection of the most suitable (cost, aging, environmental requirements, etc) connectivity for 
automotive applications with very different requirements compared with data-centers.

In summary, I believe every parameter needs to be revised according to target automotive application, with experimental or simulation data.

Best regards, 


Rubén Pérez-Aranda 
CTO at KDPOF
_____________________________________________________________

Knowledge Development for POF, S.L.
A: Ronda de Poniente 14 2º CD, 28760, Tres Cantos (Madrid), Spain 
P: +34 91 804 33 87 Ext:110 
M: +34 689 319 866

El 24 feb 2021, a las 7:12, Takashi Fukuoka <fukuoka-takashi@xxxxxxxxx> escribió:

Hello Steve,

Thank you for your contribution.

I have a comment on the below statement:

> 300.8.2.2.2 Maximum discrete reflectance
> The maximum discrete reflectance shall be less than TBD dB.

According to the other IEEE802.3 optical PHY standards, the optical reflection 

(optical reflection tolerance for optical transmitter) shall be less than -12dB.

I think we'd better to follow the wisdom of old people as far as there is no particular reason.

RIN influenced by optical reflection is varied by the design of both VCSEL chip and optical coupling system,

so that it will be easier (with lower cost) to purchase them in the market.

The attached letter might be good to understand the definition of optical reflection of the channel.

Best regards,

Takashi Fukuoka


On 2021/02/24 0:49, Swanson, Steven E wrote:
All,
 
On the IEEE 802.3cz call today, I provided a contribution on baseline text for the PMD/MDI (attached). I would like to make a motion to adopt this text as part of the baseline text at our next interim meeting as we move to D1.0.
 
The purpose of this note is twofold:
 
  1. Can I ask you to review the contribution and let me know if you have any comments to improve the text?
  2. Can I ask you to review the contribution and let me know if I can add you as a supporter for the contribution?
 
I would like to get your input prior to Friday, March 5 so I can make any necessary changes and submit for consideration by IEEE 802.3cz at our March 16 interim meeting.
 
Thanks,
 
Steve
 
Steven E. Swanson
Senior Standards Manager
Distinguished Associate
 
Global Technology & Industry Standards
MT&E
Corning Optical Communications
4200 Corning Place
Charlotte, NC 28216
 
m 607-725-1129
 
 
Standards are a bridge between markets and technologies; whoever controls the bridge controls the future…

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福岡　隆（Takashi Fukuoka）
Sumitomo Electric Industries, Ltd.
TEL:090-8139-4491 (Direct)
e-mail: fukuoka-takashi@xxxxxxxxx
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