Re: FW: [EFM-P2MP] FW: [EFM] EFM FEC Proposals
Raanan,
why is the disparity checking function affected differently
from any of the other 8B/10B coding rules? Perhaps
I am missing something, so I would like you to elaborate,
perhaps providing a brief example of a scenario that you
think would cause trouble.
Howard
Raanan Ivry wrote:
>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@majordomo.ieee.org;
>stds-802-3-efm@majordomo.ieee.org; 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@majordomo.ieee.org
>>Cc: stds-802-3-efm@majordomo.ieee.org
>>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@majordomo.ieee.org
>>Cc: stds-802-3-efm@majordomo.ieee.org
>>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
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
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