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Joseph,
You state:
2-The complete list of PAM5 advantages
are:
a-Lower SNR
b-More tolerant to AFE nonlinearity
c-Significantly lower
power
I do agree with (a)
and with (b) though, to avoid confusion I would state (a) as Lower SNR required.
Both (a) and (b)
will reduce AFE power consumption requirements so I agree with (c) also. It
is good that we agree on this at a qualitative level.
The higher baud rate
does however do the following:
(d) Increase
equalizer and canceller lengths
(e) Increase the
required clock rate at which the above run
Because of (d) and
(e) the digital power consumption goes up - to a first order as the square of
the symbol rate - so going from 800Msym/sec to 1.2Gsym/sec will, to a first
order, increase digital power by a factor of 2.25. Again this is a qualitative
argument.
As for the capacity
calculations with SolarFlare's program, I will leave it to people from
SolarFlare to respond.
To estimate system
performance, you need to calculate the SNR available at the receiver and compare
this to the SNR required. For capacity calculations, any transmitted power
making it to the receiver counts as signal. For system operation, part of the
signal power making it to the receiver, if not equalized, will add to the noise
rather than to the signal. The way to estimate actual received SNR is to adapt a
DFE with a reasonable number of taps and see what this turns out to
be.
I can't recall
whether someone put up Matlab code to do this SNR calculation up on the
reflector. If it is, can someone point us to it?
Regards, Sanjay
cell (650) 704-7686
office (408)
653-2235
From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On Behalf Of Joseph Babanezhad Sent: Wednesday, May 19, 2004 3:25 AM To: STDS-802-3-10GBT@LISTSERV.IEEE.ORG Subject: Re: [10GBT] [SPAM] [10GBT] symbol rate Sanjay,
In May of 1998 at the CICC conference while waiting
to present my paper
I was listening to Mehdi Hatamian of Broadcom, one
of the movers & shakers
of IEEE 1000BASE-T standard, give his tutorial
presentation on 802.3ab standard
draft. There was one thing that he kept repeating
it over and over ... and over again;
"Remember the most important things for Ethernet
are power, power and power"
If this was relevant to 1000BASE-T it definitely is
more relative to 10GBASE-T.
With this in mind let me address your
comments:
1-Please do not confuse PAM4 with PAM5
PAM4 baud-rate=1.56 GB/s
Nyquist-frequency=780 MHz
PAM5 baud-rate=1.25 GB/s
Nyquist-frequency=625 MHz
2-The complete list of PAM5 advantages
are:
a-Lower SNR
b-More tolerant to AFE nonlinearity
c-Significantly lower
power
3-As far as channel's higher IL & ANEXT at
frequencies beyond 500 MHz are
concerned the following are the capacity simulation
results using SolarFlare's
provided program from the web-site:
Launch Power : 7 dBm (2Vpp PAM5)
nextcanc=50; echocanc=65; fextcanc=50;
(1) for model # 1
17.38 Gbps
(2) for model #2
solarsep_varlen7a(-10.5,650,4,55,6,1,6,2)
18.40 Gbps
(3) for model #3
solarsep_varlen7a(4.5,650,4,100,6,1,6,2)
17
Gbps
Regards,
Joseph N. Babanezhad
Plato Labs.
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