Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: [8023-10GEPON] Define TDP values



Thanks Pete,
the reference was added to the list of changes for version 2.2.
BR

Marek Hajduczenia (141238)
NOKIA SIEMENS Networks S.A. – COO BBA DSLAM R&D
Rua Irmãos Siemens, 1, Ed. 1, Piso 1
Alfragide, 2720-093 Amadora, Portugal
* marek.hajduczenia@nsn.com
(+351.21.416.7472  4+351.21.424.2082

 


From: Pete Anslow [mailto:pja@NORTEL.COM]
Sent: segunda-feira, 10 de Dezembro de 2007 10:14
To: STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: Re: [8023-10GEPON] Define TDP values

Marek,

 

This definition follows from the procedure defined in 802.3 subclause 58.7.9.

 

Regards,

Pete Anslow

 

Nortel Networks UK Limited, London Rd, Harlow, Essex CM17 9NA, UK

External +44 1279 402540 ESN 742 2540

Fax +44 1279 402543

 


From: Hajduczenia, Marek [mailto:marek.hajduczenia@nsn.com]
Sent: 07 December 2007 15:49
To: Anslow, Pete (HAL02:Q840); STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: RE: [8023-10GEPON] Define TDP values

 

Hi Pete,

thanks for the clarification on the definitions. I guess I did not know how to put into words what I was thinking about.

Is the TDP definition You provided for the record an official definition (i.e. could be put in the spreadsheet for reference) ?

BR

Marek Hajduczenia (141238)
NOKIA SIEMENS Networks S.A. – COO BBA DSLAM R&D
Rua Irmãos Siemens, 1, Ed. 1, Piso 1
Alfragide, 2720-093 Amadora, Portugal
* marek.hajduczenia@nsn.com
(+351.21.416.7472  4+351.21.424.2082

 

 


From: Pete Anslow [mailto:pja@NORTEL.COM]
Sent: terça-feira, 4 de Dezembro de 2007 16:43
To: STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: Re: [8023-10GEPON] Define TDP values

Marek,

 

[Marek Hajduczenia] In other words:

TP = worst_case Tx (test Tx) + best_case PON (no dispersion, pure attenuation) + best_case Rx (ideal Rx)

DP = worst_case PON (with dispersion and attenuation) - best_case PON (no dispersion, pure attenuation)

Correct ?

 

I would characterize it as:

 

TP = Test Tx with pure attenuation – Ideal Tx with pure attenuation

DP = Test Tx with worst_case PON (with dispersion and attenuation) - Test Tx with best_case PON (no dispersion, pure attenuation)

 

And just for the record:

 

TDP = Test Tx with worst_case PON (with dispersion and attenuation) - Ideal Tx with pure attenuation

 

In all cases the receiver would be a test receiver as used in Tx manufacturing test.

 

[Marek Hajduczenia] Isn't this what Frank pointed out as ITU path penalty definition ?

Yes, it is similar, but strictly ITU path penalty also includes any penalty due to reflections from the optical path and some (unspecified) allowance for PMD (Polarisation Mode Dispersion).  My comment was driven by people proposing to make the test (Dispersion_Penalty+TDP) <= ITU_Optical_Path_Penalty.  This would be more obviously wrong if it read (Dispersion_Penalty+TDP) <= Max_Dispersion_Penalty

 

Regards,

Pete Anslow

 

Nortel Networks UK Limited, London Rd, Harlow, Essex CM17 9NA, UK

External +44 1279 402540 ESN 742 2540

Fax +44 1279 402543

 


From: Hajduczenia, Marek [mailto:marek.hajduczenia@nsn.com]
Sent: 04 December 2007 15:57
To: Anslow, Pete (HAL02:Q840); STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: RE: [8023-10GEPON] Define TDP values

 

 

Pete,

I comment inline (again)

BR

Marek Hajduczenia (141238)
NOKIA SIEMENS Networks S.A. – COO BBA DSLAM R&D
Rua Irmãos Siemens, 1, Ed. 1, Piso 1
Alfragide, 2720-093 Amadora, Portugal
* marek.hajduczenia@nsn.com
(+351.21.416.7472  4+351.21.424.2082

 

 


From: Pete Anslow [mailto:pja@NORTEL.COM]
Sent: segunda-feira, 3 de Dezembro de 2007 9:11
To: STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: Re: [8023-10GEPON] Define TDP values

Ken,

 

The equation you propose for row 53 still does not make sense.  TDP and ITU_Optical_Path_Penalty are not equivalent measures since TDP includes the non-ideality of the transmitter waveform and ITU_Optical_Path_Penalty does not.

 

If the group wants to call out the two components of TDP separately then we need:

 

A user input cell for Maximum Transmitter Penalty TP (penalty due to non-ideal eye shape at the transmitter)

A user input cell for Maximum Dispersion Penalty DP (further penalty caused by the link dispersion)
[Marek Hajduczenia] These would be user input values based on some feasible test ? In the case of TP component, we would need an ideal transmission channel (transmitter tested in a back-to-back setup ?) and in the case of DP component, would we need ideal transmitter and try to see how an ideal waveform is distorted by the non-ideal dispersive medium ?

[Pete] These values would be based on the TDP measurement defined in subclause 58.7.9.  The TDP value is the difference between the receiver sensitivity measured with the test transmitter through worst case dispersion and the value “S”. Here TP would be the difference between the receiver sensitivity measured with the test transmitter with no dispersion and the value “S”.  DP would be the difference between the receiver sensitivity measured with the test transmitter with and without worst case dispersion.  The nearly ideal transmitter is only used to establish the value of “S”.
[Marek Hajduczenia] In other words:

TP = worst_case Tx (test Tx) + best_case PON (no dispersion, pure attenuation) + best_case Rx (ideal Rx)

DP = worst_case PON (with dispersion and attenuation) - best_case PON (no dispersion, pure attenuation)

Correct ?

 

A calculated cell for Maximum TDP (TDP = TP + DP)

A cell which calculates the actual dispersion penalty (which is already there)

 

I think that it would probably be a good idea to remove the reference to ITU_Optical_Path_Penalty from the DP row as it seems to cause confusion rather than help.
[Marek Hajduczenia] There is no such reference IMHO. The only comparison right now between the T(D)P and optical path penalty is in the row where the test is carried out on both values, which as You pointed out above - is still imperfect.

[Pete] Row 27 of 3av_0709_linkmodel_v2_1.xls is currently:

ITU_Optical_Path_Penalty          3.00      dB        Optical path penalty in accordance with ITU definition
[Marek Hajduczenia] What I meant is that the path penalty is not related with the TDP apart from the test condition ...  

 

I am proposing to change this to something like:

DP        2.00      dB        Optical penalty due to dispersion (max)
[Marek Hajduczenia] Isn't this what Frank pointed out as ITU path penalty definition ?  

And add a separate line such as:

TP        1.00      dB        Optical penalty due to non-ideal transmitter (max)

These two adding together to give TDP

TDP      3.00      dB        Transmitter AND Dispersion Penalty (max)
[Marek Hajduczenia] From this breakdown, it seems that we should probably remove the term ITU path penalty and specify exactly what is meant there ... this way we have the parameter already in the spreadsheet - just its meaning would be different ... still, I think  that in this context, it is a synonimous to ITU optical path penalty

 

The test would then become:

Dispersion_Penalty <= DP

 

If we go the way You propose and include the DP and TP user input fields, we need to specify exactly what these penalities represent. Otherwise, we risk again confusion. Are there any "commonly accepted" tests which could allow to estimate the values of such penalty components in laboratory conditions?

[Pete] As defined in subclause 58.7.9 see earlier response.

 

The test in row 53 would then become Is Calculated_dispersion_penalty <= DP?

 

We have no way of calculating an estimate of TP, so there is no way to make this test involve TDP rather than DP alone.

 

As discussed earlier, if an additional cell for achievable receiver sensitivity was to be introduced then a second test for the overall power budget could be added.

 

Is Min_Tx_Pow – TDP – Max_channel_loss > Rx_Sens?

 

The Min_Tx_Pow and Rx_Sens would be in OMA and Rx_Sens would have to be referred to the sensitivity you would get with an ideal transmitter for this to work.
[Marek Hajduczenia] I imagine the Rx_Sens would be again the user input field ?  

[Pete] Yes

 

Regards,

Pete Anslow

 

Nortel Networks UK Limited, London Rd, Harlow, Essex CM17 9NA, UK

External +44 1279 402540 ESN 742 2540

Fax +44 1279 402543

 


From: Ken Maricondo [mailto:kmaricondo@IEEE.ORG]
Sent: 30 November 2007 04:17
To: STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: Re: [8023-10GEPON] Define TDP values

 

Dear All,

 

Thank you all for the feedback and clarification.  In reviewing all of the recent threads, I think that we all can agree that a penalty is a penalty.   Therefore, I suggest that the spreadsheet be change to reflect the following:

1.       Change the TDP cell (A39) to only be TP

2.       Change the Transmitter Dispersion Penalty cell (D39) to Transmitter Penalty

3.       Change Dispersion_Penalty <= ITU_Optical_Path_Penalty cell (A53) to Transmitter_+_Dispersion_Penalty <= ITU_Optical_Path_Penalty or TDP <= ITU_Optical_Path_Penalty

4.       Change cell (D53) formula to =IF((B38+B39)<=B30,"PASSED","FAILED")

 

In the absence of hard TDP data, I think that this will allow the user to put in a transmitter penalty value, while other users who might think that the TP is overkill can put in a value of zero.  At a later date and when TDP data is available, I think that we can readdress this issue.  What do you think?

 

Best regards,

 

Ken Maricondo

 

 

On Nov 29, 2007 3:10 PM, Frank Chang <ychang@vitesse.com> wrote:

Hi Pete;

 

I am very happy you chime in to clarify the confusion which exists for a while in the email thread and also associated mtg discussions so far. I also feel the term "TDP" or even "stress RX sens" was misinterpreted in link budget formalism, which is quite inconsistent with what is defined in IEEE 802.3 for the TP2 and TP3 methodology.  

 

FYI- In line with what you said, actually I provided a tutorial to elaborate this during July mtg as follows:

 

Best Regards

Frank C.

-----Original Message-----
From: Pete Anslow [mailto:pja@nortel.com]
Sent: Thursday, November 29, 2007 3:13 AM
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON] Define TDP values

Hi,

The way the term " TDP" is being discussed in this thread seems to me to be inconsistent with the way it is defined in IEEE 802.3.

TDP stands for Transmitter and Dispersion Penalty.   It is the penalty due to the combination of the eye closure of the transmitter and the further eye closure caused by the link dispersion.

The TDP measurement procedure for 1000Base PX10 and PX20 is defined in subclause 58.7.9 .  The sensitivity of the reference receiver is measured with as near an ideal test transmitter as possible and then this is corrected for any residual transmitter eye closure to give the sensitivity with an ideal transmitter S.  Then the receiver sensitivity is measured again using the transmitter under test through the worst case dispersion .  T he TDP value is then the difference between the second measurement and S.

If we label the two penalty components as EP for the transmitter Eye Penalty (penalty due to non-ideal eye shape at the transmitter) and DP for the transmitter Dispersion Penalty (further eye closure caused by the link dispersion ) then we can say:

TDP = EP + DP

Now, for most ITU-T power budgets Path Penalty is approximately equal to DP (and the specified receiver sensitivity has to be met using a transmitter with a worst case EP ).

Consequently, Dispersion_Penalty <= ITU_Optical_Path_Penalt y makes reasonable sense.

The inequality (Dispersion_Penalty+TDP) <= ITU_Optical_Path_Penalt y makes no sense at all as it is roughly equivalent to saying:

DP + (EP + DP) < = DP

I agree that Dispersion_Penalty <= ITU_Optical_Path_Penalt y is not sufficient to establish that the power budget is feasible with available optics.  As I understand the current spreadsheet, it calculates the receiver sensitivity that would be required given the various input parameters.  In order to test for the feasibility of this sensitivity value an additional input cell containing the achievable receiver sensitivity with a n ideal transmitter would be required.

Regards,

Pete Anslow

Nortel Networks UK Limited, London Rd, Harlow, Essex CM17 9NA, UK

External +44 1279 402540 ESN 742 2540

Fax +44 1279 402543

_____________________________________________
From:
Hiroshi Hamano [mailto:hamano.hiroshi@JP.FUJITSU.COM]
Sent: 29 November 2007 02:55
To: STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject:
Re: [8023-10GEPON] Define TDP values

Dear Dr. Maricondo,

Thank you very much for your explanations, and I apologize for my late reply.

Now, I understand that, in your E-mail, (Dispersion_Penalty+TDP) means the dispersion penalty value using a realistic transmitter with worst case TDP, in contrast to that using an ideal or perfect transmitter with small or no TDP.

I am not sure, whether (Dispersion_Penalty), in the Spreadsheet, is figured out based on such an ideal transmitter or not, but I agree that the result should indicate the worst case value in order to d ecide the fail/pass condition.

But I am not sure either, how TDP should be counted into such transmitter parameters for calculating (Dispersion_Penalty+TDP), in the Spreadsheet, and how big its impact will be.  If you have any suggestions, that will be qu ite helpful.

If TDP value should be derived from the measurement results, not from Spreadsheet calculations, some penalty value may remain only assumed and uncalculated, unless the relationship between the measured TDP and Dispersion_Penalty is justified.

Any comments or discussions will be highly appreciated.

Best regards,

Hiroshi Hamano

%% "Ken Maricondo" <kmaricondo@ieee.org> %% Re: [8023-10GEPON] Define TDP values %% Fri, 23 Nov 2007 17:07:53 -0500

>

> Dear Hamano-san and Hajduczenia,

>

> I agree (from all that I have read) that the ITU_optical_path_penalty

> basically includes no transmitter penalty and that receiver

> sensitivity value in ITU formalism should share the TDP within the

> margin. The rationale as to why I suggested adding the TDP to

> *Dispersion_Penalty <=

> ITU_Optical_Path_Penalty* is as follows:

>

> 1.    Any penalty such as chirp, extinction ratio, MPN, etc., will require

> that the photodiode receiver to receive an increased proportional

> optical receive level in order to maintain the same BER verse a system

> without the same penalties. The *Dispersion_Penalty <=

> ITU_Optical_Path_Penalty* from what I can tell assumes an ideal

> transmitter and receiver over a given optical path and that only if

> the dispersion penalty exceeds the optical path penalty then the link

> fails.  If I use only dispersion penalty in a network calculation

> without the TDP, then I am not truly taking into account worse

> case/end of life network performance.  In my point of view, a network

> designed with a TDP of 3dB for example will have a shorter operational

> lifetime or be performance limited then an identical network with an

> ideal transmitter with no TDP or lower value of TDP.  So to compensate for the TDP a more robust FEC scheme or higher quality receiver might be in order.

>

> 2.    I do not discount or object to the TDP value from being subtracted

> from the *IEEE_Rx_Stressed_Sensitivity_OMA* to get *IEEE_Rx_Sen_OMA*,

> but I think that TDP should show up in the system margin as worse

> case/end of life calculation within the spreadsheet.  The fact that

> the receiver sensitivity has to go lower to compensate for the TDP

> only points out that I have to have a higher quality ideal receiver at first glance.

>

> I am acutely aware of the fact that 10GEPON standard will allow for

> degree of flexibility in the network design to compensate for network

> design short comings.  My suggestion for *(Dispersion_Penalty+TDP) <=

> ITU_Optical_Path_Penalty* to be changed is to make sure that there is

> no ambiguity in the standard (spreadsheet) and to point out to the

> adopter of the 10GEPON standard that *all* penalties have been

> accounted for, analyzed and documented.  At the end of the day it is

> up to task force as whole to adopt what they feel is appropriate for the standard.

>

> Best regards,

>

> Ken Maricondo

>

>

>

>

> On Nov 22, 2007 5:27 AM, Hiroshi Hamano

> <hamano.hiroshi@jp.fujitsu.com>

> wrote:

>

> > Dear Dr. Maricondo and Dr. Hajduczenia,

> >

> > Thank you for your quick response and discussion.

> > I am not sure how TDP values have been defined in the previous

> > specifications such as IEEE 802.3ae and 802.3ah.  If they have also

> > reflected the vendor data based on the transmitter measurement

> > results, vendor feedbacks may be quite important similarly for

> > 10GE-PON.

> >

> > > but should read *(Dispersion_Penalty+TDP) <=

> > > ITU_Optical_Path_Penalty* to insure all possible noise and

> > > penalties

> > are

> > > accounted for.

> >

> > Perhaps, I misunderstand the last sentence of Dr. Maricondo's E-mail.

> > But my understanding is that ITU_optical_path_penalty basically

> > includes no transmitter penalty.  Receiver sensitivity value in ITU

> > formalism should share the margin, instead, for possible transmitter

> > penalty compared to the ideal one.

> > Would you please explain again your intension about the sentence??

> >

> > Best regards,

> > Hiroshi Hamano

> > Fujitsu Labs. Ltd.

> >

> > %% "Ken Maricondo" <kmaricondo@ieee.org> %% Re: [8023-10GEPON]

> > Define TDP values %% Wed, 21 Nov 2007 19:15:31 -0500

> >

> > >

> > > Dear Hamano-san,

> > >

> > > Although the TDP is a controversial value to be added to the

> > > 10GEPON standard, I have to agree with the previous committee (

> > > 802.3ah) for assigning a TDP value; albeit not an apparent

> > > benefit, the TDP does set

> > a

> > > reference value/point for determining transmitter quality which

> > > does

> > impacts

> > > system performance.  I agree with your assessment that the lack of

> > > high power reference transmitter to make a TDP measurement at this

> > > time is a problem.  In the absence of such a reference

> > > transmitter/s, I think that

> > the

> > > TDP values you have chosen are a good reference point to start

> > > with and

> > I

> > > support you on this issue.

> > >

> > > I also think that the spreadsheet should reflect the impact of TDP

> > > on

> > the

> > > systems' overall performance.   From what I have been able to determine,

> > the

> > > TDP value is subtracted from the

> > > *IEEE_Rx_Stressed_Sensitivity_OMA* to

> > get *

> > > IEEE_Rx_Sen_OMA*, which does not readily translate into a system

> > performance

> > > impact/limitation.  The system pass/fail calculation is based on

> > > *Dispersion_Penalty <= ITU_Optical_Path_Penalty* only, but should

> > > read

> > *(Dispersion_Penalty+TDP)

> > > <= ITU_Optical_Path_Penalty* to insure all possible noise and

> > > penalties

> > are

> > > accounted for.

> > >

> > > Best regards,

> > >

> > > Ken Maricondo

---

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

Hiroshi Hamano

Network Systems Labs., Fujitsu Labs. Ltd.

Phone:+81-44-754-2641 Fax.+81-44-754-2640 E-mail:hamano.hiroshi@jp.fujitsu.com

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