FW: [EFM-P2MP] FW: [EFM] EFM FEC Proposals
Howard,
It sounds reasonable.
But the disparity check functionality is different
than in old systems (because of the high BER). Is it?
Raanan
-----Original Message-----
From: owner-stds-802-3-efm-p2mp@majordomo.ieee.org
[mailto:owner-stds-802-3-efm-p2mp@majordomo.ieee.org] On Behalf Of
Howard Frazier
Sent: Thursday, July 04, 2002 7:44 PM
To: stds-802-3-efm-p2mp@xxxxxxxxxxxxxxxxxx;
stds-802-3-efm@xxxxxxxxxxxxxxxxxx; stds-802-3-efm-p2p
Subject: Re: [EFM-P2MP] FW: [EFM] EFM FEC Proposals
Raanan,
regarding your point # 1, this would represent a link
that was operating outside of the specification. If you don't have FEC
at both ends of the link, then the link must comply with the budget for
non-FEC enabled links. The behavior in the region beyond the limits of
the link budget is unspecified.
Another way of saying this is that a link comprising PHYs without FEC
either end will have a budget of X dB, and will have a BER of Y or
better as long as the link loss + penalties is less than or
equal to X.
A link comprising PHYs with FEC at each end will have a budget of
X+delta, and will have a post-FEC BER of Y or better as long as the link
loss + penaties is less than or equal to X+delta.
Operation of a link comprising "old" PHYs (without FEC at each end, and)
with a link loss + penalties of greater than X dB is outside the scope
of the specification, just as it has always been.
At least, that's the way I see it.
Howard
Raanan Ivry wrote:
>Lior,
>Some comments:
>1. Compatibility.
> When an old system receives FEC protected frames it will detect
> disparity errors (because of the low power). How will the old
system
> deal with it?
>2. Error duplication.
> In both schemes you can correct 8 symbols. 8 or 10-bit symbols.
> The error probability of 10-bit symbol is higher, therefore the
>performance
> of the S-FEC is better for AWGN.
> 80 bits burst protection is not required, so this is not an
>argument. 3. Byte and frame alignment.
> In upstream you have the preamble and delimiter so additional
> alignment is not required.
> In downstream, since the sync byte is always in the beginning of a
> fixed length frame, alignment is very robust (and was proven in lot
> of standards).
>
>Best regards,
>Raanan
>
>
>-----Original Message-----
>From: owner-stds-802-3-efm-p2mp@majordomo.ieee.org
>[mailto:owner-stds-802-3-efm-p2mp@majordomo.ieee.org] On Behalf Of Lior
>Khermosh
>Sent: Wednesday, July 03, 2002 7:29 PM
>To: Ajay Gummalla; Larry Rennie; stds-802-3-efm-p2mp@xxxxxxxxxxxxxxxxxx
>Cc: stds-802-3-efm@xxxxxxxxxxxxxxxxxx
>Subject: RE: [EFM-P2MP] FW: [EFM] EFM FEC Proposals
>
>
>Hi Ajay,
>I have attached a few slides with some remarks regarding the
>Stream-FEC.
>
>
>Best Regards,
>Lior
>
>
>
>
>-----Original Message-----
>From: owner-stds-802-3-efm-p2mp@majordomo.ieee.org
>[mailto:owner-stds-802-3-efm-p2mp@majordomo.ieee.org]On Behalf Of Ajay
>Gummalla
>Sent: Tuesday, July 02, 2002 8:43 PM
>To: Larry Rennie; stds-802-3-efm-p2mp@xxxxxxxxxxxxxxxxxx
>Cc: stds-802-3-efm@xxxxxxxxxxxxxxxxxx
>Subject: [EFM-P2MP] FW: [EFM] EFM FEC Proposals
>
>
>Larry and all:
> I have attached a slide which compares the two proposals.
>I am hoping that this will generate more discussions and help us make
>progress.
>
>Please take a look at
>http://www.ieee802.org/3/efm/public/jul02/p2mp/gummalla_p2mp_1_0702.pdf
>for the calculations on efficiency.
>
>Best Regards,
>Ajay
>
>>-----Original Message-----
>>From: owner-stds-802-3-efm@majordomo.ieee.org
>>[mailto:owner-stds-802-3-efm@majordomo.ieee.org]On Behalf Of larry
>>rennie
>>Sent: Monday, July 01, 2002 6:31 PM
>>To: stds-802-3-efm
>>Subject: [EFM] EFM FEC Proposals
>>
>>
>>
>>Fellow EFM Task Force Members,
>>
>>At the last EFM meeting in Edinburgh we passed the following FEC
>>motion:
>>
>>17. Motion to add an FEC option for the 1Gig P2P and P2MP PHY,
>>maintaining backward compatibility with the 1000BASE-X PCS, for the
>>following reasons:
>> 1. Improves reach of a MPN limited link by 50% for links with MPN
>>penalty of about 2dB
>> 2. Permits operation at a SNR lower by 2.5 dB for non-dispersion
>>limited links.
>>
>>Two different FEC implementation proposals will be presented in
>>Vancouver and they are posted under the General Session material on
>>the EFM web site. One proposal is frame based and the other is stream
>>
>
>>based. If you are at all interested in FEC for EFM, I encourage you
>>to please take a look at these two proposals and get your comments and
>>
>
>>questions back onto the reflector before the meeting. This will give
>>the presenters and their supporters time to formulate a proper
>>response and will conserve our precious meeting time in Vancouver.
>>
>>Regards,
>>
>>Larry
>>
>>
>>
>>
>>
>>
>
>
>