Re: [10GBT] Channel models

[Dave.Hess@NEXANS.COM]

Chris,

Very nicely and shortly put!

I don't see how much longer we can put off having a next generation channel model to go along with another next generation cabling.

I have seen several papers circulated, for >1 yr now giving various treatments for full cascaded xmsn line segment models

Our modeling TG appears to have gaps in its attention

There is some recent work in IEC that might soon gain some attention

we can't vote on math!

best regards
Dave

CDimi80749@AOL.COM Sent by: stds-802-3-10gbt@IEEE.ORG 05/13/2004 09:31 AM Please respond to "IEEE P802.3an"

To:        STDS-802-3-10GBT@LISTSERV.IEEE.ORG         cc:                 Subject:        Re: [10GBT] Channel models

Sanjay,
 
Short answer:
The traditional simple transmission line models utilized to predict far-end crosstalk (below 100 MHz) do 
not account for common mode propagation (and termination) and neglect far-end reflections. Many of the
traditional references assume that like pairs in a cable have identical propagation constants (magnitude and phase),
and the lines are terminated in their characteristic impedance.  These effects (combined) can result in measurable 
differences between the FEXT of pair ij and the FEXT of pair ji.
 
Regrads,
 
Chris
 
 
 
In a message dated 5/12/2004 6:40:31 PM Eastern Standard Time, SKasturia@TERANETICS.COM writes:
Bryan,

Good question. I assumed that FEXT between pair i and j would be the
same as between j and i. Thinking about it some more, I am not sure if
that is correct. Can others let us know what measurements have revealed?


Chris DiMinico, can you answer this?


Sanjay

sanjay@teranetics.com
cell (650) 704-7686
office (408) 653-2235

-----Original Message-----
From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
Behalf Of Sparrowhawk, Bryan
Sent: Wednesday, May 12, 2004 4:19 PM
To: STDS-802-3-10GBT@listserv.ieee.org
Subject: Re: [10GBT] Channel models

Sanjay,
I have a question about your terminology regarding far end crosstalk in
"c)".
Could you have meant twelve pair combinations for FEXT instead of 6?
Or do you speak of "Far end crosstalk" as others speak of 'reverse
NEXT'?
Bryan S.

-----Original Message-----
From: Sanjay Kasturia [mailto:SKasturia@TERANETICS.COM]
Sent: Friday, April 09, 2004 3:36 PM
To: STDS-802-3-10GBT@listserv.ieee.org
Subject: [10GBT] Channel models

We have four channel models defined from the March 2004 plenary meeting.


For detailed PHY performance simulations, we will need sample channel
data that complies with these models.

We will greatly appreciate it if any task force participants can provide
full matrix (4x4) channel data. This would ideally include:
a) Insertion loss data on each of four pairs - real and imaginary
b) Near end crosstalk coupling (6 unique pair-combinations) - real and
imaginary
c) Far end crosstalk coupling (6 unique pair-combinations) - real and
imaginary
d) Four unique echo transfer functions (one for each pair) - real and
imaginary

This can be obtained by measurements on actual cable and then scaling to
meet the specified channel models.
Any cable companies volunteering to provide this data?

There is some data from the cabling Ad-hoc available on:
http://www.ieee802.org/3/an/public/material/index.html
This data has some of the items listed above but not all. It does,
however, provide enough to get some sense of performance.

Sanjay Kasturia

sanjay@teranetics.com
cell (650) 704-7686
office (408) 653-2235