Re: [8023-10GEPON] Ad hoc on 10GEPON channel model - definitions
Dear Paul,
first of all, thank You for a very interesting email. I
found it informative and I think I agree with Your point of view on the TDP
parameter - I still need to analyze the test procedure in more detail and see
whether it will impact in any way the definition of the power budget for the PON
plant.
I also like Your idea on providing the TDP value as a
normative metric for the standard defined power budget while the individual
parameters incorporated in the overall system loss/penalties should be defined
in more detail, as we all agree I think. PON environment is very specific and we
really want to optimize the power budget for the specific reach parameters. At
least that is what I think we should do, at least in the case of two higher
power classes.
Attached please find an updated release of the document
with definitions with TDP definition and some changes introduced yesterday as a
result of an email exchange with Mike Dudek (thanks for Your time Mike).
All comments and suggestions how to fill in the missing
fields are more than welcome.
Best wishes
BTW. The TDP is defined in clause 58.7.9 if I am not
mistaken ... "58.7.9 Transmitter and dispersion penalty (TDP)
measurement"
Mike and Marek,
The latest IEEE link budget methodology that Mike stated
is optimal for transceiver makers because it distills a collection of separate
transmitter tests into a single test parameter called TDP. It also permits
maximal trade-off between all the parameters that contribute to TDP.
While these are positive
attributes to this approach, it is not without its down sides. By lumping
parameters together, the standard no longer needs to specify limits on the
underlying constituents. This removes the boundary conditions on the
constituents that if specified would allow optimizing solutions to address
various cases not covered within the scope of the standard. These cases
include variations in topologies and media types not included in the standard.
It is my opinion that allowing this kind of flexibility is advantageous
because it permits optimal deployment in a greater variety of situations.
Please consider these
trade-offs as the specifications are written into the standard. One way to
address both sides is to use TDP as the normative metric, and provide
informative values on the limits of the constituent parameters consistent with
the TDP spec.
Regards,
Paul Kolesar
CommScope Enterprise® Solutions
1300
East Lookout Drive
Richardson, TX 75082
Phone:
972.792.3155
Fax: 972.792.3111
eMail:
pkolesar@commscope.com
| "Hajduczenia, Marek"
<marek.hajduczenia@SIEMENS.COM>
12/13/2006 11:32 AM
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"Hajduczenia, Marek"
<marek.hajduczenia@SIEMENS.COM> |
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| Re: [8023-10GEPON] Ad hoc on
10GEPON channel model - definitions |
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Dear Mike,
The FC-PI-2 and FC-PI-4 are inherently the same in
terms of the definitions I quoted but I will change the reference for the sake
of using only stabilized and released specifications. Thank You for that
comment.
Regarding the receiver sensitivity, there are two definitions
provided. Number one is quoted after FC-PI-2 and says "The minimum acceptable
value of re-ceived signal at point γR to achieve a BER < 10-12.". The
alternative is quoted after T1.523-2001 and says "The minimum value of average
received power to achieve a 1 x 10–10 bit error ratio. It includes power
penalties caused by use of a transmitter under standard operating conditions
with worst-case values of extinction ratio, pulse rise and fall times, optical
return loss, receiver connector degradations, and measure-ment tolerances." Is
that clear right now ? Sorry for the wording in the original document. I will
try to clarify that ...
Thank You also for the suggestion on the power
budget estimation based on OMA - it was also suggested by Piers to have a look
in that direction and that is what I am doing right now. I am afraid that I am
still a little bit confused with the spreadsheet but I will figure it out with
time. I will have to look into which terms require proper definitions in order
to have the power budget defined in the way You mentioned before. I will try to
have a look at it today and come back to You tomorrow.
Thank You for
Your time
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
-----Original Message-----
From: Mike
Dudek [mailto:mike.dudek@PICOLIGHT.COM]
Sent: quarta-feira, 13 de Dezembro
de 2006 16:43
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re:
[8023-10GEPON] Ad hoc on 10GEPON channel model - definitions
A few
comments on these definitions.
I would caution the use of FC-PI-4.
This is a draft standard that is in development, and therefore is likely
to contain errors. That said the definitions are unlikely to change and
are mostly copied (maybe all copied) from the released document FC-PI-2.
At this point however I would recommend that FC-PI-2 is used.
I
know that this is not easy to incorporate into a matrix, but it is fairly common
practice in the datacom world to create the exact definitions of what is meant
by a particular term through the use of a test procedure. Eg.
Transmitter and Dispersion penalty (TDP) for the 1G EPON clause 60 (which is in
802.3 2005) is defined by reference to the test procedure of clause 58.8.9.
As you noted there are significant differences between link
penalties (IEEE) and Optical Path penalty (ITU) and lumping them into the same
row in the matrix may add to confusion. However as these use different
names it is not that confusing. More of a problem is "receiver
sensitivity" AKA "intrinsic sensitivity". As normally used in the IEEE and
Fibre Channel context (including it's use in the various link budget
spreadsheets) this is the performance of the receiver when tested with a perfect
transmitter. I don't see the definition you have provided in the matrix
stated as coming from FC-PI-4 in FC-PI-4. I would be grateful if you would
provide the exact page reference for it, because in the FC-PI-4 document this
would be an incorrect definition and needs to be corrected if it exists.
The definition as stated I think is more like how ITU defines sensitivity
including the effect of transmitter impairments, (the definition may have come
from FDDI which is a much older A!
NSI standard).
Note that in my
opinion the budgeting method used in 802.3 Clause 52 (10G serial) is probably
the best method to achieve plug and play operation for a system which has a
challenging budget to meet.
In summary this method is as
follows.
The budget is based on Optical Modulation Amplitude at both the
Tx and Rx, (So variations in extinction ratio don't affect the
budget).
The difference between the sensitivity measured with a reference
receiver between a near perfect Tx with a short fiber, and the device under test
Tx with a long fiber with a worst case dispersion characteristic is measured and
called Transmitter and Dispersion penalty (TDP). (hence TDP
includes all Transmitter and Dispersion penalties relative to a near perfect
Tx.).
The Receiver is tested with a signal that emulates the worst case
signal at the end of a worst case dispersive fiber. (ie emulating a Tx
with the worst case Transmitter and Dispersion penalty.). This is the
Receiver's Stressed receiver sensitivity.
The link budget closes
(ie system is OK) provided the loss in the link is less than "minimum Tx OMA
-TDP" - Rx stressed receiver sensitivity. Note that the key
Tx parameteter specified is the (Tx OMA - TDP).
-----Original
Message-----
From: Hajduczenia, Marek [mailto:marek.hajduczenia@SIEMENS.COM]
Sent: Wednesday, December 13, 2006 5:39 AM
To:
STDS-802-3-10GEPON@LISTSERV.IEEE.ORG
Subject: Re: [8023-10GEPON] Ad hoc on
10GEPON channel model - definitions
Dear Frank,
Attached please find
an updated matrix list. It contains several new definitions, which - being
unable to find them in the 802.3, I went to ANSI standards to find the
respective terms defined. Some of them are still missing and I am trying to find
some comprehensive and yet recognized defnitions for such parameters.
I also
added a wish list, which would probably need to be added if we want to go into
details with the channel impairments and penalties.
Feel free to
modify/add/change ...
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
-----Original Message-----
From:
EffenbergerFrank 73695 [mailto:feffenberger@HUAWEI.COM]
Sent: quarta-feira,
13 de Dezembro de 2006 8:09
To:
STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON] Ad hoc on
10GEPON channel model - definitions
> All,
>
> Marek
offers a good starting point of a definition cross-reference
> matrix.
> I have taken this, and filled in the ITU side.
>
> We should probably make more items in this matrix, to include at
> least the Tx min and max, and Rx sensitivity and overload. Those
> are somewhat different between the two systems, too.
>
> Regards,
> Frank E
>
>
Terminology - release v2.2 .doc