Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: AW: [802.3ae_Serial] Issue with 1500 Power




Juergen,

You are less confused than you say!  I have compared my understanding with
yours: see below.  There are some editorial/clarity issues and one
outstanding point which is: is the 802.3ae D3.1 ER/EW receive sensitivity
very demanding or expensive?

Piers

> -----Original Message-----
> From: Rahn, Juergen (Juergen) [mailto:krahn@xxxxxxxxxx]
> Sent: 03 July 2001 09:01
> To: 'Mike Dudek'
> Cc: stds-802-3-hssg-serialpmd@xxxxxxxx; 'Ron Miller'
> Subject: AW: AW: [802.3ae_Serial] Issue with 1500 Power
> 
> 
> Sorry,
>  I am still confused.
> You talk about ISI penalty now but this is stated at transmitter power
> anyway and not quantified. 
> In the table it reads:
> Launch power (min) in OMA minus TDP * -1.39 dBm
> with a note:
> * TDP is transmitter and dispersion penalty
> up to now I interpreted that we have to consider the 
> penalties and than
> compensate the penalties by increasing the power (Whatever 
> the penalties
> are) First question is this a correct understanding?

Yes

> If yes you will not have any advantage at the receiver when 
> increasing the
> power by the amount of penalty as a penalty represents the decrease in
> sensitivity, so this should add up to zero.

Yes

> (It comes to my mind that the - in this parameter suggests 
> that the power
> may be decreased by the penalties which would give trouble 
> but this may be a
> short editorial discussion)

Juergen please make a comment.  Editor please note!
 
> If this understanding is correct let me make the calculation:
> Simple case ideal transmitter no penalties :
> Launch power (min) in OMA minus TDP * 		-1.39 dBm
> 
> Stressed receive sensitivity (max) in OMA ?, ? , §		
>  (-11.40)
> (dBm)
> 
> I calculate an attenuation budget of about 10 dB out of this not 13db.

No, you have it right below.

> However there is a term in the receiver table  .
> ( I interpret max sensitivity here also as a minimum 
> requirement, I don not
> hope that this means the sensitivity should not be better 
> than this value,
> but this may be an editorial problem)

Maximum is more dBm, representing worst case for a receiver sensitivity, so
I think this one is the right way round.  Please make a comment if any doubt
remains.

> Vertical eye closure penalty ** (max) 3.0 dB
> with a note
> **Vertical eye closure penalty is a test condition for 
> measuring stressed
> receive sensitivity. It is not a required charac-teristic
> of the receiver.
> This note is a bit misleading for me, however I interpret 
> this note in the
> way that when measuring stressed sensitivity there has to be 
> used a signal
> that has 3 dB penalty, what means that for a signal that does 
> not show this
> penalty  ( as assumed at the transmitter in this 
> consideration)  we can add
> this to the sensitivity. Is this the ISI penalty you mention? 
> In this case
> we really at the end coming out with 13 dB budget.
> Calculation would look like:
> _________________________________________________________
> transmitter OMA min	 				  -1.39	dBm
> _________________________________________________________
> receiver sensitivity (OMA)		 -11.40	dBm
>  + receiver test signal penalty	           	    3.0	dB
> _____________________________________________
> Total )penalty free signal) sensitivity in OMA		
>  -14.4	dBm
> __________________________________________________________
> attenuation budget	   				   
> 13.01	dB
> 
> So can you confirm this understanding ?

Yes.

> If not would it be possible to set up a similar calculation 
> like this and
> clarify.
> 
> If this understanding is correct than we have 14.4 dBm sensitivity
> requirement in OMA and this for instance get it comparable to 
> transponders
> you can by translates (being optimistic into average power 
> sensitivity of :
> - 14.4 dBm OMA will give -17.4 dBm ideal ER sensitivity or 
> -16 dBm (average
> power sensitivity) at ER of 8.2 dB as used in ITU. This is 2 
> dB harder as
> ITU and represents the BOL typical value that you get  for 
> such components.
> For an interface spec we however require EOL worst case!
> For my understanding this is not realistic today and if done will be
> expensive.

Is it relevant to point out that SONET receiver sensitivities are
standardised for a "worst" Tx eye which has the same 3 dB penalty?  Not sure
if you have already taken that into account.
 
> Regards Juergen Rahn
> 
> 
> > ----------
> > Von: 	Mike Dudek[SMTP:mdudek@xxxxxxxxxxxx]
> > Gesendet: 	Dienstag, 3. Juli 2001 03:02
> > An: 	Rahn, Juergen (Juergen)
> > Cc: 	stds-802-3-hssg-serialpmd@xxxxxxxx; 'Ron Miller'
> > Betreff: 	Re: AW: [802.3ae_Serial] Issue with 1500 Power
> > 
> > 
> > A further attempt to clarify this.
> > The 3dB difference is the ISI penalty that is imposed when 
> performing the
> > stressed receiver sensitivity test which corresponds to the 
> maximum value
> > of the
> > Transmitter and Dispersion Penalty of the Transmitter.  If one has a
> > transmitter
> > that produces this amount of penalty then one has to 
> increase the output
> > power
> > by 3dB.  Hence the 13dB is attained.
> > Regards Mike
> > 
> > "Rahn, Juergen (Juergen)" wrote:
> > 
> > > Hi
> > > The difference between current defined sensitivity and 
> what would be
> > > required (straightforward without any additional margin 
> penalty....) is
> > 3
> > > dB, what means the attenuation budget would be 10 dB.
> > > Does this clarify?
> > > Regards Juergen
> > >
> > > > ----------
> > > > Von:  Ron Miller[SMTP:rmiller@xxxxxxxxxxx]
> > > > Gesendet:     Mittwoch, 27. Juni 2001 18:10
> > > > An:   Rahn, Juergen (Juergen); 
> stds-802-3-hssg-serialpmd@xxxxxxxx
> > > > Betreff:      RE: [802.3ae_Serial] Issue with 1500 Power
> > > >
> > > >
> > > > juergen
> > > >
> > > > Please check your numbers below.  Thanks
> > > >
> > > > Ron Miller
> > > >
> > > > -----Original Message-----
> > > > From: Rahn, Juergen (Juergen) [mailto:krahn@xxxxxxxxxx]
> > > > Sent: Wednesday, June 27, 2001 3:30 AM
> > > > To: stds-802-3-hssg-serialpmd@xxxxxxxx
> > > > Subject: AW: [802.3ae_Serial] Issue with 1500 Power
> > > >
> > > >
> > > >
> > > > Hi,
> > > > as discussed in the PMD call I understand there is a 
> mismatch in the
> > > > values
> > > > defined for the 1550 case. The minimum transmitter OMA 
> is  -1.39dBm +
> > > > penalties. Link attenuation is set to 13 dB , so this 
> would give a
> > > > sensitivity requirement of -14,39 dBm OMA ,. however 
> the stressed
> > > > sensitivity (In OMA) is defined to be -11.4 dBm.
> > > >
> > > >  so there are 10 dB
> > > > difference between those two values.
> > > >
> > > > LOOKS MORE LIKE ABUT 3 DB TO ME.
> > > >
> > > > The trade off that has been introduced
> > > > (that I do not like, but this is a different 
> discussion) will shift
> > this
> > > > complete link power level. When comparing this with powers and
> > > > sensitivities
> > > > as defined in ITU the following appears: ITU defines 2 
> dB path penalty
> > > > with
> > > > this OMA we would end at a minimum transmitter power average of
> > about -
> > > > 1
> > > > dBm which is in line to ITU. with 109 dB attenuation 
> there is margin
> > in
> > > > the
> > > > ITU numbers, with 11 dB and ITU sensitivity (Which has 
> been confirmed
> > by
> > > > measurements) we add up to 0. ( -14 dBm average power 
> sensitivity and
> > 2 dB
> > > > penalty gives us the G.691 application). When simply taking this
> > > > transmitter
> > > > power and 13 dB attenuation we end up with 2 dB better 
> sensitivity
> > > > requirement as currently experienced by measurements 
> (worst case EOL).
> > > > This may start this conversation.
> > > > Regards Juergen
> > > >
> > > >
> > 
>