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Re: [10GBT] Discussions on precoder decisions


Is the "Double Square" constellation the same as the "Checkerboard"
constellation you were telling me about last week? If not, this would be the
5th constellation I've heard about from the PAM12 camp.

Here's the list so far:

1. Original PAM-12 "donut" constellation.
2. PAM-12 Compapiano-Glazer "cross" constellation.
3. PAM-12 multi-dimensional "Kabob" constellation.
4. Checkerboard constellation.
5. PAM8/16 Double Square constellation.

A general observation is that instead of researching PAM12 constellations,
the task force would be well served if we can converge around the PAM-8
proposal and conduct a working session on the standards draft at the interim


>From: Gottfried Ungerboeck <g.ungerboeck@BLUEWIN.CH>
>Reply-To: "IEEE P802.3an" <STDS-802-3-10GBT@LISTSERV.IEEE.ORG>
>Subject: Re: [10GBT] Discussions on precoder decisions
>Date: Wed, 15 Sep 2004 10:56:34 +0200
>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
>selected preferrably during auto negotiation.
>Regards, Gottfried
>   _____
>From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
>Of George Eisler
>Sent: Mittwoch, 15. September 2004 06:03
>Subject: Re: [10GBT] Discussions on precoder decisions
>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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