Regarding the question on spectrum from Brian,
The spectrum on Slide 6 and 7 (https://www.ieee802.org/3/dg/public/May_2024/Tingting_3dg_01_29_10_2024.pdf) is achieved by averaging 4000 spectrum and each spectrum corresponds to 393216 PAM2 symbols generated from random
bits. As shown following, introducing the delimiters to the 4B6B PAM2 training sequence does not change the spectrum. It is a good solution for fast synchronization, which of course depends on the application requirement.
Without considering delimiters, PMA training using PAM2 instead of 8B6T only requires 4B6B encoding and decoding, the hardware complexity of which I believe is negligible.
PAM2 training has many advantages. PAM2 is more robust than PAM3. Rx DSP converges much easier and faster especially in low SNRs, indicating easier for longer distance transmission. Besides, PAM2 training also allows
the equalizer to work stably when the transmitted signal is switched from PAM2 to PAM3, regardless of the operation mode (traditional or PR). Therefore, the risk of training failure is minimized while the training efficiency is increased and the coding gain
brought by the PR equalization is ensured.
Bests,
Tingting
-----邮件原件-----
发件人: George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>
发送时间: 2024年10月30日
1:46
收件人:
STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
主题: Re: [802.3_SPEP2P] dg meeting today October 29
Dieter - I believe Tingting was referring to PAM-2 at the same line signalling rate (baud) as the 100 Mbps PAM-3 signal would be (i.e., 80 MBaud). This way the attenuation is the same as it will be for run-time PAM-3...
(otherwise I don't see how the training would work usefully...)
George Zimmerman, Ph.D.
President & Principal
CME Consulting, Inc.
Experts in Advanced PHYsical Communications
george@xxxxxxxxxxxxxxxxxxxx
310-920-3860
-----Original Message-----
From:
stds-802-3-spep2p@xxxxxxxxxxxxxxxxx <stds-802-3-spep2p@xxxxxxxxxxxxxxxxx> On Behalf Of Dieter Schicketanz
Sent: Tuesday, October 29, 2024 10:41 AM
To:
STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Subject: dg meeting today October 29
Regarding last presentation today (Tingting Zhang), it is my understanding that of coarse PAM2 needs 4 dB less S/N but at 500m the signal attenuation is much higher than for PAM3. Is that considered ?
Because of time constraints I withdrew this question today.
--
Best regards
Dieter Schicketanz
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