Re: [8023-10GEPON] Define TDP values

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On Nov 28, 2007 9:55 PM, Hiroshi Hamano <hamano.hiroshi@jp.fujitsu.com> wrote:

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 decide 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 quite 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
-----------------------------------------