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At the March meeting, some of the discussion on leaving the door open to the higher baud rates was aksing to have time to run simulations with the higher baud rates to validate the optimal DFE results presented.
The MATLAB code has been available on the 802.3an web site for a while now – I assume others have now seen that the ANEXT model we agreed to (49.5-15log10(f/100)) is within a couple dB of the insertion loss at 650 MHz – which means that the penalty for signaling at rates over 500 MHz, where the SNR gets pinched off, is extreme. (to run this case, use: parameters: solarsep_varlen7a(-10.5,650,4,55,6,1,6,2) ).
What these curves tell you is simply that at more than 1Gbaud, you are simply signaling faster than the channel can support, and thus starting out in an SNR hole in building a 10GBASE-T system.
Hopefully at the meeting we can agree to constrain the baud rates and begin to focus our analysis.
The objectives do require that we provide one PHY that meets at least 100 meters on Class F and at least 55 to 100 meters on Class E. A proposed PHY must meet both these distance requirements. To take this a step further, a PHY or port type has traditionally referred to one PCS, one PMA and one PMD. So this could be seen as one PHY which has only one PCS, one PMA and one PMD is required to meet both the distance objectives.
In the past, the Working Group has asked the Task Forces to make the tough decisions and to choose only one PCS, PMA and PMD to meet the objective. If the Task Force chooses PAM5, then the decision is made. If the Task Force chooses PAM10, then the decision is made. If the Task Force chooses PAM5 and PAM10, then the Working Group will likely send the specification back to us to make a decision.
To quote the movie Highlander, "There can be only one."