Re: [10GBT] PAM8 and PAM12 sys time domain analysis
Sailesh,
When the line transformers (specified roughly as per
presentations the group has seen so far) are included in the
analysis -- the channel shows additional ~5.6 dB of loss at
500 MHz. See attached graph.
This, combined with Tx 1 Vp launch constraint at the IC, but
not at MDI, accounts for the bulk of SNR losses w.r.t. "ideal"
Class E channel Salz SNR.
The actual SNR loss in the time-domain bench vs. its frequency
domain reference proves to be below 1 dB -- this would be a very
hard target to achieve for any practical h/w implementation of
10GBASE-T.
Regards,
Albert
sailesh rao wrote:
> Albert,
>
> I assumed that the reference to Model 3 in your report included ANEXT
> with a
> 64.5dB intercept and other worst-case impairments, as agreed upon in the
> task force.
>
> If there was no ANEXT or residual Echo/NEXT/FEXT in your simulations,
> then I
> calculate the implementation loss in your simulations to be at least
> 3.6dB
> for PAM8 and at least 4.0dB for PAM12.
>
> I don't think we should be contemplating such implementations for
> 10GBASE-T.
>
> Regards,
> Sailesh Rao.
> srao@phyten.com
>
>> From: Albert Vareljian <albertv@IEEE.ORG>
>> Reply-To: "IEEE P802.3an" <STDS-802-3-10GBT@listserv.ieee.org>
>> To: STDS-802-3-10GBT@listserv.ieee.org
>> Subject: Re: [10GBT] PAM8 and PAM12 sys time domain analysis
>> Date: Fri, 30 Jul 2004 00:20:13 -0700
>>
>> Hi Jose,
>>
>> No ANEXT or other impairments except -140dBm/Hz were employed in sims
>> covered in the report.
>>
>> Adding ANEXT would seem to be the next logical step. However, correctly
>> modeling ANEXT may prove a bit tricky.
>>
>> As we already discussed on IEEE floor -- our agreed ANEXT models
>> are specified only in terms of the frequency domain magnitude (no
>> phase). So, the time-domain implementation has been left open up
>> to the user...
>>
>> There could be many interpretations as to how one arrives at a
>> reasonably behaved time-domain ANEXT TF and its excitation method.
>> Our analysis indicates that end results in the system could vary
>> significantly on the case by case basis, depending on the methodology
>> used to model time-domain ANEXT behavior.
>>
>> Based on the above, it may be helpful if the group agrees on and adopts
>> some "uniquely" defined causal, scalable time-domain capable model
>> for ANEXT that could be used for system qualification. One possible
>> example of ANEXT TF implementation in s-domain (usable in time- and
>> frequency- sims) is illustrated in the attachment.
>>
>>
>> Regards,
>>
>> Albert
>>
>>
>>
>>
>> Jose Tellado wrote:
>>
>>> Hi Albert,
>>>
>>> Thank you for your detailed time-domain report, I have a couple of
>>> simple questions on the simulation assumptions.
>>>
>>> Have you included the effects of ANEXT in these simulations? If so,
>>> what
>>> approved PHY channel model (1-4) would this approximate?
>>>
>>> Did you include other receiver impairments such as residual EC/NX/FX or
>>> did you lump all these effect into the -140dBm/Hz noise?
>>>
>>> Regards,
>>> Jose Tellado
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
>>> Behalf Of Albert Vareljian
>>> Sent: Monday, July 26, 2004 7:57 PM
>>> To: STDS-802-3-10GBT@LISTSERV.IEEE.ORG
>>> Subject: [10GBT] PAM8 and PAM12 sys time domain analysis
>>>
>>> Hi All,
>>>
>>> Pls find attached pdf report on PAM8 and PAM12 systems time domain
>>> simulation and comparative analysis.
>>>
>>> Regards,
>>>
>>> Albert Vareljian
>>>
>>>
>>>
>> << ANEXT_Fig.doc >>
>
>
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channel_xf_tf.doc