RE: [802.3ae_Serial] Consistent treatment of sensitivities and ma rgins
Paul,
I think that the test equipment introduced noise should be taken into
account when determining the stressed sensitivity. For example, if you are
using a transmitter which has a RIN which is worse than the standard specs,
you will add negative penalty. Similarly for the other penalties. If you
don't, your stressed receiver sensitivity will be double counting some of
the penalties. So, to answer your question, any penalty present, should be
taken into account. To do that, you will need to calibrate your system,
something that you anyway want to do.
What I am proposing is ot take into account these penaltires that are
anyway present in the system and have a consistent way of calculating the
stressed receiver sensitivity and be addressed in the standard.
Also, please see Piers' answer.
Regards,
Petar Pepeljugoski
IBM Research
P.O.Box 218
Yorktown Heights, NY 10598
e-mail: petarp@xxxxxxxxxx
phone: (914)-945-3761
fax: (914)-945-4134
"Kolesar, Paul F (Paul)" <pkolesar@xxxxxxxxxx>@majordomo.ieee.org on
10/10/2001 03:25:31 PM
Sent by: owner-stds-802-3-hssg-serialpmd@xxxxxxxxxxxxxxxxxx
To: "DAWE,PIERS (A-England,ex1)" <piers_dawe@xxxxxxxxxxx>, Petar
Pepeljugoski/Watson/IBM@IBMUS
cc: "'802.3ae Serial'" <stds-802-3-hssg-serialpmd@xxxxxxxx>, "'Tom
Lindsay'" <tlindsay@xxxxxxxxxxxxxxxxxxxx>
Subject: RE: [802.3ae_Serial] Consistent treatment of sensitivities and ma
rgins
Petar,
are you proposing that the test bench impairments be determined and
subtracted from the stresses on the receiver during the stressed receive
sensitivity test? If so, would this not require the same consideration for
each of these impairments:
> Modal noise, Reflection noise, Mode partition noise, Relative intensity
> noise, Anticipated Tx baseline wander?
>
Paul
> ----------
> From: Petar Pepeljugoski[SMTP:petarp@xxxxxxxxxx]
> Sent: Wednesday, October 10, 2001 2:52 PM
> To: DAWE,PIERS (A-England,ex1)
> Cc: '802.3ae Serial'; 'Tom Lindsay'
> Subject: Re: [802.3ae_Serial] Consistent treatment of sensitivities
> and margins
>
>
>
> Hi all,
>
> going quickly through the note, I noticed that the RIN and reflection
> penalty are categorized as impairments not included in the shape of the
> stressful eye. While it is true that the shape does not include the RIN
> and
> the reflection penalty, the system will have some amount of both RIN and
> reflection penalty. In the calculation of the stressed receive
sensitivity
> those should be taken into account, as the test laser may have smaller or
> larger RIN. The same applies for reflection penalty. One can argue that
> depending on the test pattern there will be or not some baseline wander.
>
> I believe we need to clarify this and avoid confusion.
>
> Peter
>
>
> Petar Pepeljugoski
> IBM Research
> P.O.Box 218
> Yorktown Heights, NY 10598
>
> e-mail: petarp@xxxxxxxxxx
> phone: (914)-945-3761
> fax: (914)-945-4134
>
>
> "DAWE,PIERS (A-England,ex1)" <piers_dawe@xxxxxxxxxxx>@majordomo.ieee.org
> on
> 10/10/2001 02:10:39 PM
>
> Sent by: owner-stds-802-3-hssg-serialpmd@xxxxxxxxxxxxxxxxxx
>
>
> To: "'802.3ae Serial'" <stds-802-3-hssg-serialpmd@xxxxxxxx>
> cc: "'Tom Lindsay'" <tlindsay@xxxxxxxxxxxxxxxxxxxx>
> Subject: [802.3ae_Serial] Consistent treatment of sensitivities and
> margins
>
>
>
>
> I had an action with Tom Lindsay to document the proposed consistent
> treatment of sensitivities and margins which has gained consensus on the
> serial PMD conference calls. Here it is:
>
> First, a description of where we are
> ------------------------------------
> Apart from the errors, the position in draft 3.2 and link model 2.4.1 is:
>
> Budget = Tx power - Informative Rx sensitivity
>
> Budget = Impairments + Losses + Margin
>
> Where informative Rx sensitivity is also known as "nominal" or
> "unstressed" sensitivity, and here "Impairments" are penalties apart from
> (broadband) optical attenuation or loss.
>
> Also draft 3.2 and link model 2.4.1 have (slightly simplified):
>
> Stressed Rx sensitivity = Tx power - Losses
>
> The principle is that the impairments are recreated by creating the
> stressful test eye. However, we noticed that margin was treated
> differently
> in the stressed and nominal sensitivities. Also, impairments that are
not
> recreated by the test eye are effectively being ignored in the stressed
Rx
> sensitivity calculation.
>
> Second, a description of where we think we should be
> ----------------------------------------------------
>
> Stressed Rx sensitivity = Informative Rx sensitivity + impairments
> included
> by the shape of the stressful test eye
>
> and also
>
> Stressed Rx sensitivity = Tx power - Losses - impairments not included by
> the shape of the stressful test eye - Margin
>
> Subtracting the first equation from the second we get
>
> Informative Rx sensitivity = Tx power - Losses - all impairments - Margin
>
> as before.
>
> To simplify this description, questions of measurement at TP3 versus TP4,
> mean power versus OMA, and triple trade offs, are not mentioned. They
are
> orthogonal questions to this one, which is what do we want stressed Rx
> sensitivity to mean?
>
> Now we had to split the impairments into two categories.
>
> Impairments which are included by the shape of the stressful test eye:
> Inter symbol interference penalty P_ISI
> Deterministic jitter penalty P_DJ
> The part of Rx baseline wander which is exacerbated by the shape of
> the stressful test eye
>
> This class are all pattern dependent penalties. The first two items
> combine
> to the "vertical eye closure penalty" in D3.2 52.9.13 Conformance test
> signal at TP3 for receiver testing.
>
> Impairments which are not included by the shape of the stressful test
eye:
> Modal noise
> Reflection noise
> Mode partition noise
> Relative intensity noise
> Anticipated Tx baseline wander
>
> The second class are noise-like, mainly non-pattern dependent penalties.
>
> The proposed link model 10GEPBud3_1_14.xls implements nearly all of this.
> The fine detail of the baseline wander (in Pcross) is simplified and we
> have
> found an error in the Rx stressed OMA column: it should not contain Pmn.
> This error does not affect anything but the stressed sensitivities in
> cases
> with multimode fiber.
>
> In the draft standard there is no line item called "Margin" any more. In
> general we have spent most of it on penalties. But it was worth going
> through this exercise to account properly for all the noise-like terms in
> the stressed sensitivity test which is now our only normative receiver
> sensitivity criterion.
>
> Piers
>
>
>