Re: [8023-10GEPON] [CHANNEL_LINK] New Excel spreadhseet available ...
Dear Dr. Effenberger,
Thank you for your quick comment.
I understood how to use spread sheet and TDP will not be calculated by
spread sheet.
To describe optical link model, OPP and LOSS_max will be
necessary.
Let me confirm again,
There are no necessity to define TDP in standard.
Is it right understanding?
Regards.
Naoto Saeki
> -----Original Message-----
> From: Frank Effenberger [mailto:feffenberger@HUAWEI.COM]
> Sent: Wednesday, June 27, 2007 11:02 PM
> To: STDS-802-3-10GEPON@listserv.ieee.org
> Subject: Re: [8023-10GEPON] [CHANNEL_LINK] New Excel spreadhseet
> available ...
>
> Dear Saeki-san and All,
>
> I was also tasked with working on the spreadsheet with Marek, and I owe
> him
> some suggestions on the equation style, and how it will be used. So, I'll
> take your Email as the trigger to force me to discuss it, here:
>
> Basic ideas: ITU Style is what we would like to use; however, we'd also
> like
> to capture the OMA method, since this allows for cheaper optics. That
said,
> we also want to allow users to enter in average power values, because this
> is the basis in which most researchers 'think in'.
>
> So, I propose the following:
>
> Preliminaries: The group decides on two extinction ratios that will be
used.
> The first is the 'nominal ER', and is a pretty good value (e.g., 9dB).
This
> is used to convert the nominal average power into OMA.
>
> The second is the 'worst case ER', and is a pretty bad value (e.g., 6 dB).
> This is a hard limit on the optics, just to prevent shot noise overload.
>
> For each direction, we have a budget:
> User enters in the nominal minimum average power and the maximum average
> power at the nominal extinction ratio (9 dB.)
>
> Spreadsheet calculates the OMA that this corresponds to. The OMA is the
> real requirement on the optics. Call it OMA_tx
>
> User enters in the fiber length, the split ratio, and excess loss.
>
> Spreadsheet calculates the maximum link loss to include: Fiber (calculated
> from formula), splitter (calculated from formula), and excess loss (user
> entry). Call it LOSS_max
>
> User enters in the desired dynamic loss range.
>
> Spreadsheet calculates the minimum link loss to be the maximum loss -
> dynamic range. Call it LOSS_min
>
> User enters an optical path penalty (e.g, 1 dB). This path penalty is
> defined in the ITU style, which is the penalty that is caused by the
optical
> path interacting with a worst-case signal. Call it OPP
>
> User enters the nominal receiver sensitivity and overload at the nominal
> extinction ratio (9 dB.) Note that this sensitivity is the worst case
> sensitivity of a back-to-back Tx-attenuator-Rx test set-up.
>
> Spreadsheet calculates the OMA that the sensitivity corresponds to. Call
> it
> OMA_rx
>
> Spreadsheet now can perform two tests to confirm if link works:
> OMA_rx < OMA_tx - LOSS_max - OPP
> Overload > Max_tx_power - LOSS_min
>
> That's it!
>
> This method has very little in the way of equations or other flim-flam.
> However, we like equations, because they give us a way to gauge if our
> assumptions are way off. For example, we calculate what we think the link
> loss should be (based on splitters and fiber), but we also reserve the
> 'excess loss' category to fix up the number to make the total loss what
> we
> want.
>
> In the case of optical path penalty, this value is user entered. However,
> the spreadsheet should have a side calculation that estimates the OPP
based
> on the optical values we have available. I believe that at 10G, the
> predominant factor is chromatic dispersion, and we saw the equation for
> that
> in the presentation in May. So, the spreadsheet can calculate the OPP
based
> on those equations, and perhaps print the value right next to where the
> user
> plugs in his manual value. I would expect that the user-entry should be
> close to the theoretical value, but it doesn't need to match it.
>
> (Needless to say, the flaw in that theory is that we need a chirp
parameter,
> but the chirp parameter is measured only by finding out the OPP. So, the
> theory is really circular in its methodology. The theory is only a guide,
> and the real spec is the OPP. In other words, the Tx must be required to
> produce an OPP that is less than the value entered by the user. That may
> sound upside down (that the OPP is a requirement on the Tx), but it is the
> truth.)
>
> I hope that is clear enough.
>
> Regards,
> Frank E.
>
>
>
>
> -----Original Message-----
> From: NAOTO SAEKI [mailto:n-saeki@bl.jp.nec.com]
> Sent: Wednesday, June 27, 2007 5:04 AM
> To: STDS-802-3-10GEPON@listserv.ieee.org
> Subject: Re: [8023-10GEPON] [CHANNEL_LINK] New Excel spreadhseet available
> ...
>
> Dear Marek,
>
> This is Saeki of NEC Corporation.
>
> Thank you for your great effort to define Optical link model for 10GE-PON.
> I would like to know how to handle the TDP in draft text.
> As we discussed in Geneva meeting, power budget will be discussed ITU-T
> like
> model.
> Path penalty is important parameter for link model.
> With this scheme, I think that TDP will be no longer define in standard.
> Is this correct understanding?
> If you will put TDP value in standard, how can we define a appropriate
> value?
>
> I would like to hear your opinion.
>
> Best Regards.
>
> --
>