Re: [Fecframe] I-D Action: draft-ietf-fecframe-ldpc-04.txt
Vincent Roca <vincent.roca@inria.fr> Wed, 17 October 2012 11:59 UTC
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From: Vincent Roca <vincent.roca@inria.fr>
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Date: Wed, 17 Oct 2012 13:59:31 +0200
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To: "Luby, Michael" <luby@qti.qualcomm.com>
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Cc: Mathieu Cunche <mathieu.cunche@inria.fr>, Jérôme Lacan <jerome.lacan@isae.fr>, fecframe@ietf.org, Stephen Farrell <stephen.farrell@cs.tcd.ie>
Subject: Re: [Fecframe] I-D Action: draft-ietf-fecframe-ldpc-04.txt
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Mike, Thanks for your feedback. >> (1) This proposal relies upon parts of RFC 5170 for the definition of the >> underlying LDPC staircase code. However, it isn't completely explicit in >> this proposal about what exact parts/sections of RFC 5170 are to be used >> in this proposal and how. It would seem that explicit references to the >> particular sections of RFC 5170 that are being used, and exactly how these >> parts of RFC 5170 are being inherited and used, would be useful (probably >> necessary). Note that there are several codes with different FEC encoding >> IDs defined in RFC 5170, so making exact references to which parts are >> used >> and how is important. An example of how this is not at all precisely >> defined: >> >> Because of the requirement to have exactly one encoding symbol per >> group, i.e., because G MUST be equal to 1 (Section 4.1 >> <http://tools.ietf.org/html/draft-ietf-fecframe-ldpc-04#section-4.1>), >> several >> parts of [RFC5170 <http://tools.ietf.org/html/rfc5170>] are useless. In >> particular, this is the case of >> Section 5.6 >> <http://tools.ietf.org/html/draft-ietf-fecframe-ldpc-04#section-5.6>. >> "Identifying the G Symbols of an Encoding Symbol >> Group". >> >> This snippet above that says several parts of RFC 5170 are useless (very >> vague), and it seems instead it should explicitly state what >> parts are to be used and exactly how. It provides one example of >> something that is not is to be used from RFC 5170, but it seems that >> it should be the other way around, stating explicitly what should be used >> and how. I have no doubt that an implementer will find its way in RFC5170 and identify what needs to be used. With the further restriction of having G=1, the specifications of RFC5170 become fairly small (~14 technical pages, pseudo-code included) and easy to understand IMHO. We are not planning to change anything here unless the IESG asks us to do so. >> (2) This proposal references RFC 5170 and RFC 5053, and makes some >> comparisons. However, there is also RFC 6330 that is relevant and is not >> mentioned or referenced in this proposal. It would seem appropriate to do >> so. This list is not intended to be exhaustive. No other FEC scheme tries to provide an exhaustive list: RFC5053 (Raptor) does not reference any other FEC scheme, and RFC6330 (RaptorQ) / RFC6681 (Raptor(Q) for FECFRAME) only reference Raptor. More importantly. Since: 1- you noticed we impose restrictions on the way LDPC-Staircase codes are being used in section 4.1; 2- you certainly remember the discussion we had in 2009 concerning 10 out of the 13 patents mentioned in the RFC5170 IPR disclosure, whose conclusion is here: http://www.ietf.org/mail-archive/web/rmt/current/msg01384.html 3- the present I-D only considers LDPC-Staircase codes whereas RFC5170 defines two FEC schemes; you will probably conclude like us that QC's IPR disclosure for RFC5170 does not necessarily apply to this I-D. Hence our question: does QC intend to do a new IPR disclosure? When? Regards, Vincent, on behalf of the authors NB: I'm adding Stephen Farrell who first identified the IPR disclosure question during IESG review.
- [Fecframe] I-D Action: draft-ietf-fecframe-ldpc-0… internet-drafts
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Luby, Michael
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Martin Stiemerling
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Vincent Roca
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Luby, Michael
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Luby, Michael
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Vincent Roca
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Martin Stiemerling
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Martin Stiemerling
- Re: [Fecframe] I-D Action: draft-ietf-fecframe-ld… Luby, Michael