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All, I am somewhat disheartened by the lack of participation in this thread by the individuals who voiced such strong opposition to these channels last week. While I realize everyone is busy, we need to make the time to resolve this discussion about channel models, what we simulate, etc. There is some good conversation going on here, but we are not resolving any consensus. We have already impacted how this program will proceed, as I don't know how the signaling ad hoc can proceed, which means making a decision by November is impacted, which then impacts how we proceed.
So to those individuals who had such strong opinions, please express them so we may discuss them further and find some manner in which to proceed.
John
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I agree with John that short is not always better, and the SDD12 is not the only criteria that defines if a channel can be equalized correctly or not.
Since we have not converged on a signalling and electrical specification for TX and RX devices, I think it may be counter-productive to spend too much time debating the informative channel, especially if it excludes many of the existing, measured channels that have been presented. Since the data presented by John and Peter can easily be reproduced in other practical systems, I feel it is a mistake to discard it because it does not meet the informative mask for SDD12.
I really think the signaling commitee should continue work related to defining an objective simulation methodology. This would not only allow us to compare signalling methods, but it would also give everyone involved a clearer picture of what channels are "solvable". The signalling ad hoc should simulate as many channels as possible, with the goal of objectively picking the best signalling approach.
Once a signalling approach has been selected, the next step can be to extend the simulation models to take into account implementation specific limitations that may further reduce the number of channels that can be supported, but at the same time it should give some guidance to the channel ad hoc with respect to where the limits on the masks should be. Hopefully, we will emerge with a robust signalling approach and a clearer picture of what the reasonable limits of the channel are. This will include loss, xtalk, reflections, and anything else that is considered an impairment.
In summary, let's accelerate discussion around what assumptions to include in simulations, how to define a common simulation methodology, and which signalling techniques we want evaluated. I'd like to see less talk about limiting the channels we will simulate with until we know that none of the signalling schemes proposed can solve them.
Riccardo
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