RE: [EFM-P2MP] FW: [EFM] EFM FEC Proposals
Larry,
Did we take a direction for a FEC solution for both P2P and P2MP? If so, we
probably are looking for a single FEC method for both. I would like FEC
that operates well for P2MP to help meet the 20 km objective for P2MP. If
the same method for FEC works for P2P as well, that is a bonus advantage. I
am not willing to be tied to picking the best FEC for P2P that solves all
the backwards compatibility issues if it is not the best method for P2MP.
When comparing the different methods on the table I would propose to split
the issue between P2P and P2MP in the comparison table.
I look forward to those discussions, I wanted to air that thought in
advance.
-Regards, Kent
> -----Original Message-----
> From: larry rennie [mailto:Larry.Rennie@xxxxxxx]
> Sent: Wednesday, July 03, 2002 4:20 PM
> To: Ajay Gummalla
> Cc: stds-802-3-efm-p2mp@xxxxxxxxxxxxxxxxxx;
> stds-802-3-efm@xxxxxxxxxxxxxxxxxx
> Subject: Re: [EFM-P2MP] FW: [EFM] EFM FEC Proposals
>
>
>
> Ajay,
>
> Thanks for the comparison slide. I have the following comments.
>
> 1. On the Protection column you say that the S-FEC provides
> equal protection of all bits. This is not quite accurate
> since the CW synchronization bit pattern needed by both the
> S-FEC and F-FEC proposals is not, and cannot be, protected by
> the code. The F-FEC CW sync pattern happens to also contain
> the Ethernet start of frame word so it does double duty as
> both CW sync and frame sync for an FEC enabled receive node
> and a frame sync for a non-FEC (legacy) receive node. I do
> agree that the S-FEC has more freedom to come up with a
> reliable tbd sync pattern , on the other hand, the F-FEC
> proposal describes a sync pattern and pattern detection
> method using correlators that seems fairly robust.
>
> 2. On the Prior field experience column, I think that what
> is proven by G.975 is the performance of the RS(255,239) code
> in an optical link. Since both the S-FEC and F-FEC use the
> RS(255,239) code then you could say, to this extent, that
> both proposed methods are "field proven". I agree that the
> ability of the F-FEC to operate with both FEC enabled and
> non-FEC enabled nodes is not field proven, but that's where
> our job comes in ,i.e., to specify the design so that it will
> operate in the field.
>
> I'm glad were getting these issues aired and discussed before
> the meeting.
>
> See you in Vancouver?
>
> Regards,
>
> Larry
>
> Ajay Gummalla wrote:
>
> > 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.pd
> > f
> > 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
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> --------------------------------------------------------------
> ----------
> > Name: Comparison of
> FEC proposals.pdf
> > Comparison of FEC proposals.pdf Type: Portable
> Document Format (application/pdf)
> > Encoding: base64
>
>