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

[10GBT] Discussions on precoder decisions


In amongst the various topics that have been discussed on the reflector,
I haven't seen any traffic on the subject of the precoder decisions. Is
this because we have general agreement; because the differences of
opinion are irreconcilable or because no one has given it much thought
as yet?

There are a number of questions that we need to answer:

1. Do we need a fixed or variable (or multiple fixed) precoder?

Gottfried has said that we need only one or possibly a small number of
fixed precoders.

2. If we need more than one or a variable precoder then how do we define
that the receiver should choose the parameters to send (or how should it
choose the precoder to select)? How will that data be passed to the
transmitter. How will the parameters be defined?

Jose/Seki said that a 20 coefficient, 12 bit precision precoder is
required. They suggested that the HDSL2 approach could be used. The
coefficients would be determined at startup & then fixed.

Scott has said that we could use an ARMA(3,3) definition to fix 3 poles
& 3 zeros.

3. If we have a variable precoder (or even distinct fixed precoders), do
we need to adapt or change the precoder during operation?

Sailesh has said that we need a 32 tap adaptive precoder.

Have we got any further to resolving these issues? Is anyone planning on
preparing a more detailed and widely supported presentation for Ottawa?
I would be willing to host a discussion before the presentation deadline
if anyone thinks that would help.