Re: [8023-10GEPON] [CHANNEL_LINK] New Excel spreadhseet available ...
Dear Marek,
Sorry for my late reply.
A following comment relates to your file.
>>5. Cell "B42" in file "10GEPON-D[1].0.7" is specified as other_penalties
>>which represents other system penalties. However a value is derived from
>>cell "L7" in file "10GEPON-D[1].0.4_with_examples", which represents
>>Connections etc. I think this value should be included in ChIL and a
>>penalty should come from cell "V34".
>>[Marek Hajduczenia] In
>><http://www.ieee802.org/3/av/public/tools/10GEPON-D.0.7h.xls>http://www.ieee802.org/3/av/public/tools/10GEPON-D.0.7h.xls,
>>the cell other_penalties (B42) is a total of the non-linear penalties
>>(B21) and fibre plant penatlies (B22), whic includes splices, connectors
>>etc. Cell B41 (fibre_loss) includes pure fibre loss only, assuming there
>>are no connectors, PSC etc. and the channel is ideal.
>>[Marek Hajduczenia] As far as I understand the question, what You're
>>saying Tatsuta-san is that we should take the splices, connectors etc.
>>and include them in the CHIL and take the system penalties as the maximum
>>value calculated in cell V34. Please note however that the said system
>>penalty value You refer that is column V is not used in any calculations
>>apart from charting ... It is hard for me to say whether we should
>>therefore use this value or not.
>Umm..... a little complicated.
>Is not A value of "V34" used for anything except for making the chart?
>[Marek Hajduczenia] As far as I can say .... no. In terms of
>calculations, we take the difference between the Tx power and Rx
>sensitivity, substract the fibre loss, PSC loss and additional channel
>loss (splitters etc.) and what's left is what goes for penatlies and power
>margins. I am not aware how precisely one can model the RIN penalities
>etc. That would have to be explored in depth but I would say those values
>are pessimistic at best. That is at least the impression I get from the
>white paper and discussions with Piers and Pete ... In other words, in the
>spreadsheet we estimate the maximum value of the penalities we can
>tolerate in the system and do not try to estimate their values per say ...
>I hope that is clear right now.
>I thought this sheet was used for calculating a power penalty as well as
>calculating a ChIL
>[Marek Hajduczenia] Indeed it is. It just gives You the upper bound on
>how much penalty You can tolerate in the system ... As I said before, the
>formulas governing calculation of individual penalities are approximated
>at best so do not count on really precise modelling. Matlab would have to
>be used to calculate them precisely.
>If you are right, how can we calculate the penalties?
>[Marek Hajduczenia] By calculate You mean take a formula and plugin in
>some numbers and get a result. You can estimate their values in the
>extended tables (lines 15 - 34 in D.0.4) but I am not sure about their
>precision level ... Piers would have to answer that but from what I gather
>from the white paper, the modelling is simplified to be used in Excel. You
>might need to use Matlab models to produce more precise results.
>
>Sincerely yours,
>Tsutomu TATSUTA
I rechecked a relationship between IEEE802.3ah spec and the spread sheet,
and I understood your answers. If my understanding is right, there is not
so strict relationship between a value of the penalty in IEEE802.3ah spec
and the spread sheet.
So, there is still remaining one question in my head.
How can we calculate a penalty value for estimating a power budget?
I think there are two ways to estimate the power budget.
1. We decide the power budget and CHIL at first, and then we calculate the
allocation for penalty by subtracting the CHIL from the power budget.
2. We decide CHIL and the penalty at first, and then we calculate the
power budget by adding the CHIL and the penalty.
Do you have any opinions?
Sincerely yours,
Tsutomu TATSUTA