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RE: [EFM-P2MP] FW: [EFM] EFM FEC Proposals

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
    of the S-FEC is better for AWGN. 
    80 bits burst protection is not required, so this is not an
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,

-----Original Message-----
[] On Behalf Of Lior
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,

-----Original Message-----
[]On Behalf Of Ajay
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

Please take a look at
for the calculations on efficiency.

Best Regards,
> -----Original Message-----
> From:
> []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