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George,
the 128DSQ constellation
("double square") is the natural go-in-between 8 PAM and 16 PAM, much more
so than 12PAM. Contrary to 12PAM, all encoding, decoding, and precoding
operations are based on powers-of-two arithmetic. 128DSQ has been known for a
long time in the literature and its good fit with precoding has been well
described.
On precoding, please see
ungerboeck_1_0704.pdf (Portland). One fixed IIR-type precoder is enough. If the
group cannot agree on a single fixed precoder, then let it be a very small set
(2?) of fixed precoders, one being selected preferrably during auto
negotiation.
Regards,
Gottfried From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On Behalf Of George Eisler Sent: Mittwoch, 15. September 2004 06:03 To: STDS-802-3-10GBT@listserv.ieee.org Subject: Re: [10GBT] Discussions on precoder decisions Hugh,
Thanks again for taking the badly needed lead on urging along the decision
making. The precoder definition is clearly in need of consideration, although I
think it will take simulation work to really nail it down. Of course you can't
finish it if you don't get started.
On last week's call, I was surprised by the "double square"
contribution, with it's sort of 16/8 PAM flavor. It seems to open the case up
rather than converging, but I wonder what's your take on it? I was going to call
you, only to realize that I don't have your phone contact.
George Eisler
310 459-9225
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