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

Re: [10GBT] THP coefficient set clarification & robustness

Hi George,

Would you be able to post your measured line data to the reflector?
We'd like to have a look at the issue you're raising, and want to
make sure we're using the same channel data.


Glenn Golden
Principal Engineer
Teranetics, Inc.

George Zimmerman writes:
> Gottfried (& others) -
> If you could put forward your preferred set of coefficients for the THP
> on long lines, I would like to double check our simulations.  With the
> coefficients that were in your presentation, we are generally seeing
> MUCH worse results than you presented (using measured line models rather
> than your analytic models), and would like to check that we're using the
> right forms. I want to make sure that what we're seeing here is not the
> result of a "typo".
> When I look at other results, for example, Albert's posting,  the loss
> in performance due to the mismatch of a small set of THP coefficients
> relative to the actual impulse response is appearing significant - as
> Albert has pointed out.
> If this continues to be the case, Seki's earlier proposal
> (seki_1_0504.pdf) of an HDSL2-like coefficient exchange at startup (then
> fixing the coefficients) is becoming a more attractive alternative.  The
> limiting the THP to a small set saves little hardware relative to the
> chip size, and seems to account for a significant robustness risk (at
> the least), or a much larger part of the performance margin budget than
> the hardware necessary to fix it would engender.
> =20
> -george