Re: [8023-10GEPON] Ad hoc on 10GEPON channel model

[Frank Effenberger <feffenberger@xxxxxxxxxx>]

Piers,

The operator world is more complicated that that.  But, the good news is that operators have buildings full of scientists.  So in practice, “designing” and “figuring” is not too much of a burden for them.  J

Frank E.

 

 

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From: DAWE,PIERS [mailto:piers.dawe@AVAGOTECH.COM]
Sent: Friday, November 24, 2006 2:34 PM
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON] Ad hoc on 10GEPON channel model

 

Frank,

 

You say "The idea is that the operator should design his fiber route and figure out what his penalties should be."

 

This is different to what has been assumed in previous 802.3 PMDs, which is that the operator merely has to obey the specifications for the fiber plant.  He doesn't have to "design" or "figure".

 

With regard to common terms: it may be too late.  But you can create a diagram showing what an ITU-T term refers to and what and 802.3 term refers to - even if they have the same name.

 

 

Piers

-----Original Message-----
From: Frank Effenberger [mailto:feffenberger@HUAWEI.COM]
Sent: 21 November 2006 22:46
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON] Ad hoc on 10GEPON channel model

Dear Piers,

I think that there is plenty of common ground to work on here, and I’m sure that this time, we will work out a common framework of terms that will satisfy both the IEEE and ITU formalisms.  At least, that is my hope.   

As for the last sentence you mentioned, the idea is not that the optical penalty would be measured… Indeed, this would be impossible.  The idea is that the operator should design his fiber route and figure out what his penalties should be.   I think this approach is especially important for the PON application, where we may have various other systems sharing the same fiber.  In such a system, the path penalty is really beyond the control of the equipment manufacturer.  

Regards,

Frank E

 

 

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From: DAWE,PIERS [mailto:piers.dawe@AVAGOTECH.COM]
Sent: Tuesday, November 21, 2006 3:22 PM
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON] Ad hoc on 10GEPON channel model

 

Frank and all,

 

With regard to "who has the responsibility", 802.3 is aiming for an interoperability specification.  There are not just two parties: manufacturers of transmitters and receivers, and operators.  There are three: implementers of transmitters, implementers of cable plant, and implementers of receivers.  802.3 specifications aim to make clear who is responsible for what.  In particular, they make the transmitter take responsibility for its own performance and the dispersion penalty that it causes (because the transmitter implementer knows what dispersion it is to comply over).  I would imagine that some nonlinear effects which are strong functions of spectral width or dither would similarly be the transmitter's responsibility, but would also be a concern for the fiber specification.  Also, the explicit stressed sensitivity specifications makes the receiver requirements much clearer to all parties.

 

I agree with you that a standard should specify "worst-case, end-of-life parameter values".  Large unallocated margins are not usual (in Table 38-5, for example, the margins in three out of four cases arise because the same transmitters and receivers are used over different fiber types with different characteristics).

 

I notice that "power budget" is defined for all of 802.3 as follows:

1.4.273 power budget: The minimum optical power available to overcome the sum of attenuation plus power penalties of the optical path between the transmitter and receiver calculated as the difference between the transmitter launch power (min) and the receive power (min).

 

This is not the same as the link model's power budget, Tx min - unstressed Rx sensitivity max, which is consistent with e.g. Tables 38-7, 38-8 and 38-9 (and similar tables in other clauses).  As folks will not be willing to change numbers in established standards without great debate, the definition above might need to be brought into line.  IEEE Std 802.3aq does not use the term "budget" at all.  Power budgets are informative.  If you find it more helpful to focus on the maximum/minimum channel insertion losses at this stage in the project and avoid the word" budget", you are free to do so.

 

This sentence from G.957:

"For each installation, it should be verified that the total optical path penalty, which includes combined dispersion and reflection degradations, does not exceed the value..."

is concerning.  802.3 in general aims at "plug and play": without a need for a measurement of optical path penalty for each installation.

 

Piers

-----Original Message-----
From: Frank Effenberger [mailto:feffenberger@HUAWEI.COM]
Sent: 21 November 2006 18:34
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON] Ad hoc on 10GEPON channel model

Dear all,

I’ll start the ball rolling with a discussion of definitions.

I would like to speak in favor of the system of definitions that are established in G.957.  

The text below is cut from the document (I hope this snippet falls within the bounds of ‘fair use’.  In any case, the document will become open on Jan 1^st, 2007, so we needn’t be too concerned.)

I have highlighted the key text that, in my humble opinion, have been the biggest source of difference. 

The biggest “style statement” that this approach makes is one of ‘who has the responsibility’.  The manufacturers have the responsibility for the transmitters and receivers.  The operators have the responsibility for the fiber plant.  No crossing of the lines is allowed. 

So, the manufacturer’s must provide a guarantee that their transmitter will be no worse than the specification (output power, eye-mask, and spectral characteristics, mainly), and that their receivers will work as specified, even given the worst-case transmitter.  No fiber impairments are included here, and the ultimate link-test is done using an attenuator.  

Similarly, the operators must guarantee that their fiber falls within the spec.  Note that this goes beyond setting the optical loss.  The operators are responsible for any other impairments that are caused by their fiber, such as dispersion, reflections, polarization, nonlinear self-impairments, and non-linear crosstalk impairments.  If it’s caused by the fiber, it is the operator’s engineering responsibility.  

Now: of course, as we prepare the standard, we will consider all these impairments, and we will set the benchmark for how many dB’s should be allocated to them.  Also, when the standard finally boils down to listing a number, it is the ‘attenuation maximum’ that gets the top billing.  You will notice that there isn’t even a name defined for the (minimum launched power) – (receiver sensitivity).  That is not a number that is expected to be used in applications.  

Anyway, that’s my two cents.  

Sincerely,

Frank Effenberger

8      Optical engineering approach

The selection of applications and set of optical parameters covered by this Recommendation are chosen to reflect a balance between economic and technical considerations to provide the possibility for transverse compatible systems using the synchronous digital hierarchy. This clause describes the use of the parameters in Tables 2 to 4 to obtain a common system design approach for engineering SDH optical links.

8.1   Design assumptions

To meet the greatest number of application possibilities with the smallest number of optical interface component specifications, three-interface categories are assumed for each level of the SDH hierarchy. These are distinguished by different attenuation/dispersion regimes rather than by explicit distance constraints to provide greater flexibility in network design while acknowledging technology and cost constraints for the various applications.

Worst-case, end-of-life parameter values are specified in this Recommendation to provide simple design guidelines for network planners and explicit component specifications for manufacturers. As a result, neither unallocated system margins nor equipment margins are specified and it is assumed that transmitters, receivers, and cable plant individually meet the specifications under the standard operating conditions. It is recognized that, in some cases, this may lead to more conservative system designs than could be obtained through joint engineering of the optical link, the use of statistical design approaches, or in applications and environments more constrained than those permitted under the standard operating conditions.

8.2   Worst-case design approach

For a worst-case design approach, the optical parameters of Tables 2 to 4 are related as shown in Figure 3. In loss-limited applications, a system integrator may determine the appropriate application code and corresponding set of optical parameters by first fixing the total optical path attenuation, which should include all sources of optical power loss and any cable design margin specified by the system integrator. For those situations in which the system attenuation falls within the attenuation overlap region of two applications, then either set of optical parameters would apply. The most economical designs will generally correspond to the application code having the narrower attenuation range. For each installation, it should be verified that the total optical path penalty, which includes combined dispersion and reflection degradations, does not exceed the value given in 6.4.4 and Tables 2 to 4 since a higher value may lead to rapidly deteriorating system performance.

Figure 3/G.957 – Relationship of the optical parameters

For dispersion-limited systems, the system integrator may select an appropriate application code and corresponding set of optical parameters by determining the total dispersion (ps/nm) expected for the elementary cable section to be designed. The most economical design generally corresponds to the selection of the application having the smallest maximum dispersion value exceeding the dispersion value determined for the system design. Again, the total optical path power penalty should be verified as described above.

 

 

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From: Hajduczenia, Marek [mailto:marek.hajduczenia@SIEMENS.COM]
Sent: Tuesday, November 21, 2006 6:02 AM
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: [8023-10GEPON] Ad hoc on 10GEPON channel model
Importance: High

 

Dear all,

so far, 10 people registered for participation in the 10GEPON channel model ad-hoc. Here is the complete list:

 

1. Marek Hajduczenia (chair), Siemens Networks S.A. (marek.hajduczenia AT siemens.com)
2. Glen Kramer, Teknovus Inc. (glen.kramer AT teknovus.com)
3. Frank Effenberger, Hauwei (feffenberger AT huawei.com)
4. Sergey Y. Ten, Corning, (TenS AT Corning.com)
5. Keiji Tanaka, KDDI Labs, (kj-tanaka AT kddilabs.jp)
6. Eric Lynskey, Teknovus Inc., (eric.lynskey AT teknovus.com)
7. Paul Kolesar, CommScope Enterprise® Solutions, (PKOLESAR AT systimax.com)
8. Tsutomu Tatsuta, NTT, (tatsuta AT ansl.ntt.co.jp)
9. Robert Lingle, OFS Optics, (rlingle AT ofsoptics.com)
10. Dawe Piers, AvagoTech, (piers.dawe AT avagotech.com)

 

I would like to first thank everybody for their will to participate. Let's hope that this ad-hoc is as successful as the last one.

 

Regarding the tasks related with this particular ad-hoc, I would like to suggest some of them. Please feel free to provide any comments / feedback / suggestions.

 

Task 1: Channel model definitions:

    - conformance between 802.3 definitions and channel model spreadsheet

    - establish definitions for loss budget, channel insertion loss, power budget margin and its individual components

 

Task 2: Identification of necessary channel model extensions to be included in the new spreadsheet

    - non-linear transmission channel impairments (e.g. SBS?)

    - RF video overlay (?)

    - realistic PSC loss modelling

    - any other ?

 

Task 3: Overhaul of the Excel spreadsheet and update to meet requirements of the 10GEPON

    - separation of the parameter sheet and results sheet to increase readability ...

    - add missing channel impairment parameters (e.g. SBS threshold)

    - add RF channel modelling and include all related transmission impairments (+ penalties)

    - add PSC component modelling as well as include PSC loss in the channel model

    - any other which are identified by the ad-hoc

   

Task 4: Model compatibility issues

    - is Excel spreadsheet sufficient to model all the effects in 10GEPON system?

    - what are other options for publicly available software which could do the job better?

    - do we need to improve the modelling precision to remove 1-2 dB overshoot which was signalled in the case of 10GE links ?

    - any other compatibility issues ?

 

I would appreciate if the participants could identify the tasks which are of their primary interest. Feel free to email me with any suggestions regarding changes, wording, addition of tasks etc.

 

If possible, I would also like to start the discussion on the defintions of individual channel parameters, since it was suggested that we ought to clarify finally concepts like channel insertion loss and whether power budget margins should be internally divided into channel insertion loss margins and other components related with Rx/Tx equipment. I would like to suggest discussion based on the presentation from Tanaka-san, available at: http://grouper.ieee.org/groups/802/3/av/public/2006_11/3av_0611_tanaka_1.pdf

 

I am looking forward to hear Your opinions on this topic.

 

Best wishes

 

Marek Hajduczenia (141238)
SIEMENS Networks S.A. - IC COM D1 R
Rua Irmãos Siemens, 1
Ed. 1, Piso 1
Alfragide
2720-093 Amadora
Portugal
* Marek.Hajduczenia@siemens.com
http://marekhaj.easyisp.pl/index.php
(+351.21.416.7472  4+351.21.424.2082