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Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

Thank you Sudeep.

 

What strikes me, is that we are trying to create a set of specifications that are sufficient to guarantee interoperability.

In radio land, the standards are “necessary” but not sufficient to guarantee a working system/interop.

The results below and in the referenced presentation indicate that the link met BER requirements yet some failed TDECQ.

 

What I didn’t see is a bench mark of the actual receiver. If the actual receiver is much better than the oscilloscope

(better equalizer, lower noise floor, better bandwidth – merely speculating here) that makes the TDECQ measurement,

then I might expect to see similar results, i.e. better receiver performance makes up for degraded transmitter performance.

 

Why not have a TDECQ requirement that is “necessary” but not sufficient to guarantee performance.

(wait a minute, am I a Tx vendor or Rx vendor…..)

 

From: Sudeep Bhoja [mailto:sbhoja@xxxxxxxxx]
Sent: Thursday, June 22, 2017 6:24 PM
To: Bill Kirkland; STDS-802-3-400G@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

Bill,

 

We would then start discarding good optical transmitters for failing TDECQ specs due to specifying a 5 taps T/2 equalizer.

 

See http://www.ieee802.org/3/bs/public/17_05/way_3bs_01a_0517.pdf. Clearly 7-9 T spaced taps are required.  

 

 

 

Sudeep

 

From: Bill Kirkland <wkirkland@xxxxxxxxxxx>
Reply-To: Bill Kirkland <wkirkland@xxxxxxxxxxx>
Date: Thursday, June 22, 2017 at 10:18 AM
To: "STDS-802-3-400G@xxxxxxxxxxxxxxxxx" <STDS-802-3-400G@xxxxxxxxxxxxxxxxx>
Subject: Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

 

Ali, in reference to 5 taps, I think it is in part about creating a level playing field for folks using different technologies and processes.

 

(I still claim ignorance , but I believe not everyone is using CMOS/Bi-CMOS and some folks might not even be trying to use an FFE in the Rx).

I would hope that the reference receiver architecture would not “force” certain RX technology decisions unnecessarily.

 

From: Ali Ghiasi [mailto:aghiasi@xxxxxxxxx]
Sent: Thursday, June 22, 2017 12:14 PM
To: STDS-802-3-400G@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-3-400G] [PossibleSpam] Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

Gary 

 

The fundamental problem we have based on Marco’s results  is that even for 5 T spaced FFE the TDECQ is about 3.4 dB over the current limit of 2.5 dB, effectively we are short of 0.9 dB.  

 

Winston presentation indicates changing the reference EQ form 5 tap to 7 tap T spaced EQ improves TDECQ significantly.  These results all were taken with 38.9 GHz filter, I expect if the

results were taken with 26.55 GHz filter the amount of improvement from 5 taps to 7 taps would improve even more.

 

 

We have a BW problem here and we should be solving the BW issue using an equalizer with sufficient length!   Having more data will help how to better move forward, but going back to the 5 T/2 FFE 

will put us even in worse predicament.  We need to consider 7 T-spaced FFE, increase TDECQ to 3.0 dB, and improve unstressed receiver sensitivity by 0.5 dB.  

 

Forcing TDECQ to 2.5 dB will impact yield and cost of the the transmitter as it was illustrated in Winston presentation.  The worst part is that you end up trowing away good transmitters that exceed the required BER 

when tested with link partner as the commercial receivers have more capabilities than the reference equalizer.  It has been mentioned several times that we should limit the TDECQ filter to 5 taps because analog implementation are limited to 5 taps, here are some references that show longer analog FFE can be implemented

 

9 tap 32 Gb/s FFE filter in Bi-CMOS 

 

7 tap 40 Gb/s FFE in 65 nm CMOS 

 

 

Thanks,
Ali Ghiasi
Ghiasi Quantum LLC
Office (408)352-5346
aghiasi@xxxxxxxxx

 

On Jun 22, 2017, at 6:52 AM, Gary Nicholl (gnicholl) <gnicholl@xxxxxxxxx> wrote:

 

I tend to agree with Carlo. If we are not changing the receiver implementation  (king_01a_0617_smf) then why are we changing the unstressed receiver sensitivity specification ? 

 

Gary

 

Ps. I think there is a typo on slide 7 in Jonathan’s presentation. I believe that the yellow arrow below should also include MPI penalty, i.e. it should be “connector and channel insertion loss + MPI penalty” ?

 

 

 

 

 

 

<image001.png>

 

 

 

 

 

From: "Carlo Tosetti (ctosetti)" <ctosetti@xxxxxxxxx>
Reply-To: "Carlo Tosetti (ctosetti)" <ctosetti@xxxxxxxxx>
Date: Thursday, June 22, 2017 at 8:28 AM
To: "STDS-802-3-400G@xxxxxxxxxxxxxxxxx" <STDS-802-3-400G@xxxxxxxxxxxxxxxxx>
Subject: Re: [STDS-802-3-400G] [PossibleSpam] Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

Ciao Mike

 

Please note that, as Brian pointed out, Pete’s tables do show changed unstressed RX sensitivities.

If the power budget is not really changing, I would deem preferable to leave the unstressed RX sensitivity as it is (at the end of the day the SRS of the RX is not changing either, since the RX is the same) with the note that, even if ideal, the reference TX has SECQ = 0.9dB (pending Jonathan confirmation, see below).

 

 

My reasoning is as follows: under the assumption that both RX and – of course - reference TX are not changing (what is changing is the methodology for TDECQ and SECQ calculation: let me call the new one TDECQ’/SECQ’), to me it seems you cannot at the same time do the following:

1)                   apply the usual link budget calculations:

(Launch power in OMAouter minus TDECQ) - Channel IL (- MPI) = unstressed RX sensitivity

2)                   keep the unstressed RX sensitivity unchanged

3)                   assume SECQ’ of the reference TX (let me call it SECQ’ref_TX ) equal to 0dB

 

I see a couple of options. Let me rewrite the link budget calculation as follows:

 

(Launch power in OMAouter minus TDECQ) - Channel IL (- MPI) = unstressed RX sensitivity - SECQref_TX

 

When the original definitions applies (where SECQref_TX= 0), you end up with the following numbers

 

-3.5dBm – 3dB (- 0.1dB) = -6.6dBm -0dB = -6.6dBm

 

With the new TDECQ’/SECQ’ methodology the max TDECQ’ is 0.9dB higher, so you may have:

 

a)            SECQ’ref_TX = 0dB Þ (-3.5-0.9) - 3 (- 0.1) = -7.5 - 0

b)            SECQ’ref_TX = 0.9dB Þ (-3.5-0.9) - 3 (- 0.1) = -6.6 - 0.9

 

Option a) requires an improved RX performance and is consistent with the fact that a zero stress TX has 0dB SECQ’. But I find this extra requirement not justified, given the fact that the same considerations in Jonathan’s presentation regarding ‘SRS remaining unchanged’ should also apply here.

Option b) leaves the RX requirement unchanged but assumes that SECQ’ref_TX is actually 0.9dB, something that I am leaving Jonathan to confirm/reject (is the 0.9dB increase constant with stress amount? If not it would be difficult to do the usual elementary math).

Of course we’ll face the drawback/paradox that a TX with ideal properties has a SECQ’ ≠ 0dB.

 

Please correct me if I am wrong…maybe I did not correctly catch what is being proposed.

 

Thanks and regards

Carlo

 

“…non men che saver, dubbiar m'aggrata…” (Inferno - Canto XI)

 

.:|:.:|:. | Carlo Tosetti | 

CISCO | TMG Technical Leader|

 

From: Brian Welch [mailto:bwelch@xxxxxxxxxxx] 
Sent: mercoledì 21 giugno 2017 21:02
To: STDS-802-3-400G@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-3-400G] [PossibleSpam] Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

Mike,

The presentation that Pete referenced (prepared for next weeks Ad Hoc) is proposing to make the unstressed RX sensitivity more stringent by 0.9 dB, and increasing the SECQ for the SRS value by 0.9 dB.

 

Brian

 

From: Dudek, Mike [mailto:Mike.Dudek@xxxxxxxxxx] 
Sent: Wednesday, June 21, 2017 11:03 AM
To: STDS-802-3-400G@xxxxxxxxxxxxxxxxx
Subject: [PossibleSpam] Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

The definition for unstressed receiver sensitivity has always been with zero stress.   Saying that SECQ = 0dB clarifies what is meant by zero stress.      It is harder for the Rx to achieve the BER with a SECQ of 0.9dB rather than SECQ of 0dB and we aren’t changing the Unstressed sensitivity  so I don’t understand why you are saying this makes the Rx unstressed sensitivity test harder.

 

From: Carlo Tosetti (ctosetti) [mailto:ctosetti@xxxxxxxxx] 
Sent: Wednesday, June 21, 2017 1:53 AM
To: STDS-802-3-400G@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

Ciao Peter

 

I have a question related to the added text in the notes on unstressed receiver sensitivity “…and is defined for a transmitter with SECQ of 0dB”.

 

Based on such value, the proposed change in TDECQ has an impact on the RX side, as it is captured by the corrections in unstressed sensitivity values: the same RX which was OK with the reference TX when using the old TDECQ definition is now not working anymore with the new TDECQ definition and needs an improvement of 0.9dB in the unstressed sensitivity.

 

I am wondering – but honestly I am not sure if this is physically sound and consistent with the new proposed TDECQ methodology: shouldn’t the note say instead “…and is defined for a transmitter with SECQ of 0.9dB” (admittedly this looks pretty ugly…)?

 

Thanks and regards

Carlo

 

“…non men che saver, dubbiar m'aggrata…” (Inferno - Canto XI)

 

.:|:.:|:. | Carlo Tosetti | 

CISCO | TMG Technical Leader|

 

From: Anslow, Peter [mailto:panslow@xxxxxxxxx] 
Sent: martedì 20 giugno 2017 21:47
To: STDS-802-3-400G@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

Matt,

 

I think that the file I have generated for next week’s SMF Ad Hoc should answer your question:

 

Regards,

Pete Anslow | Senior Standards Advisor
43-51 Worship Street | London, EC2A 2DX, UK
Direct +44 2070 125535 |

 

From: Matt Traverso (mattrave) [mailto:mattrave@xxxxxxxxx] 
Sent: 20 June 2017 04:16
To: Anslow, Peter <panslow@xxxxxxxxx>; STDS-802-3-400G@xxxxxxxxxxxxxxxxx; Jonathan King <jonathan.king@xxxxxxxxxxx>
Subject: RE: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

Hi Jonathan,

I’m sorry to have missed the most recent ad hoc where you presented king_01a_0617_smf.  I find myself confused as to what you mean by: “a similar decrease in the OMAouterminus TDECQ spec”.  Can you show an example with what would happen for the TX or RX table for any of the clause 122 PMD’s?

 

I think this all stems from a mixing of terms increase/decrease with negative numbers…

 

Thanks

--matt

 

 

<image002.jpg>

 

Matt Traverso

PRINCIPAL ENGINEER.ENGINEERING

Cisco Systems, Inc.

3700 Cisco Way
SAN JOSE
95134
United States
cisco.com

 

 

 

 

 

From: Anslow, Peter [mailto:panslow@xxxxxxxxx] 
Sent: Tuesday, June 13, 2017 1:12 AM
To: STDS-802-3-400G@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-3-400G] IEEE P802.3bs 200 Gb/s and 400 Gb/s Ethernet SMF Ad Hoc conference call

 

Hi,

 

As previously announced, there is an SMF Ad Hoc meeting starting at 8:00 am Pacific today, Tuesday 13 June.

 

Attendees names and affiliations will be taken from the Webex participants list. Please use an e-mail address indicating affiliation when signing in. If you attend via phone only, or if your employer and affiliation are different, please send me an e-mail.

 

I currently have requests for 1 presentation so the draft agenda is:

 

    • TDECQ changes and consequent spec limits                              Jonathan King, Finisar

 

  • Discussion

 

The presentation for this call is on the P802.3bs SMF Ad Hoc web page.

If you have any questions for the presenter(s) after the call, please ask the Ad Hoc Chair for contact details.

 

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. 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Topic: "P802.3bs SMF Ad Hoc" 

Date & Time: Every 2 weeks on Tuesday, from Tuesday, 13 June 2017, to Tuesday, 27 June 2017 at 16:00, GMT Summer Time (London, GMT+01:00) 

To join web meeting click here: https://ciena.webex.com/ciena/j.php?MTID=m8af2937bfb4b6fd299ccb5ee317895fb 

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

Teleconference: Provide your phone number when you join the meeting to receive a call back. Alternatively, you can call:

+44-203-4333547  (United Kingdom)

4438636577  (United States)

2064450056  (Canada)

4006920013  (China)
Show global numbers: https://www.tcconline.com/offSite/OffSiteController.jpf?cc=7659923550 
Conference Code: 765 992 3550 


Meeting number: 632 000 521 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

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?MTID=mfc13bf723def2cc42b90e63cc52f8635 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

https://ciena.webex.com

 

Regards,

Pete Anslow | Senior Standards Advisor
43-51 Worship Street | London, EC2A 2DX, UK
Direct +44 2070 125535 |