RE: PAM-5, what are your BERs ?
I did not realize that your proposal using FEC error correction.
I thought your analyses and test data are pretty solid to achieve 10^-12
without any question. Your analysis of the receiver met BER of 10^-12. If
other components are also meeting a link specification which is similar to
the GbE specification, you should not have problem meeting the BER of 10^-12
So, which part of the link requires the FEC to achieve 10^-12? Coding
technology? Is the additional multilevel detecting requirement making EFC a
How about the component and system interoperability issue. Should we
qualify each component at BER of 10^-12 or at 10^-3 (as you mentioned in
another e-mail)? When multi vendor's components are mixed in a link, what
BER we should use in test to assure their interchangeability.
At what subsystem level, we should add FEC to qualify a link to pass BER of
The inclusion of the FEC will bring new issues to the specifications.
Of course, those issues can be resolved.
Edward S. Chang
NetWorth Technologies, Inc.
[mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Jaime Kardontchik
Sent: Wednesday, March 01, 2000 12:59 PM
Subject: Re: PAM-5, what are your BERs ?
Edward Chang wrote:
> Thanks for reminding us FEC.
> The BER defined in the standard is the actual error rate without any error
> correction. This establishes the fundamental reliability and quality
> criteria of components, systems, and technologies.
> The error correction techniques can be added as an option for applications
> which need better BER than what has been specified in the standard.
> However, this is outside of the standard.
> For cost-effectiveness, I believe users will request the specified BER in
> the standard should be sufficient without added error collection.
> Edward S. Chang
I can not agree with you on this, Edward. However, I understand
the philosophy behind this: a bare proposal without any
whistles and bells (like FEC) should still be technically
reasonable and achieve some basic reasonable and measurable
The proposal I presented, "PAM5 4-WDM at 1.25 Gbaud"
has these attributes: even without FEC the optical eye is
wide open at the input of the receiver and the static SNR
(even without FEC) is similar to the static SNR of another
respectable proposal: 8b/10b 4-WDM at 3.125 Gbaud.
In fact, without FEC it would still be 1 dB (optical) better.
(see my email "PAM-5, what are your BERs" from Feb 27).
Jaime E. Kardontchik
San Jose, CA 95131