Re: [tsvwg] I-D Action: draft-ietf-tsvwg-rlc-fec-scheme-04.txt

Vincent Roca <vincent.roca@inria.fr> Fri, 18 May 2018 07:13 UTC

Return-Path: <vincent.roca@inria.fr>
X-Original-To: tsvwg@ietfa.amsl.com
Delivered-To: tsvwg@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id A4B29127333 for <tsvwg@ietfa.amsl.com>; Fri, 18 May 2018 00:13:20 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.9
X-Spam-Level:
X-Spam-Status: No, score=-6.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5] autolearn=unavailable autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5SiOMwWCnrtX for <tsvwg@ietfa.amsl.com>; Fri, 18 May 2018 00:13:18 -0700 (PDT)
Received: from mail3-relais-sop.national.inria.fr (mail3-relais-sop.national.inria.fr [192.134.164.104]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 8326D12711A for <tsvwg@ietf.org>; Fri, 18 May 2018 00:13:17 -0700 (PDT)
X-IronPort-AV: E=Sophos;i="5.49,413,1520895600"; d="scan'208";a="265639231"
Received: from dom38-1-82-236-155-50.fbx.proxad.net (HELO [192.168.1.101]) ([82.236.155.50]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 May 2018 09:13:15 +0200
From: Vincent Roca <vincent.roca@inria.fr>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Mime-Version: 1.0 (Mac OS X Mail 11.3 \(3445.6.18\))
Date: Fri, 18 May 2018 09:13:14 +0200
References: <152662627753.1538.3506303682099297675@ietfa.amsl.com>
To: tsvwg@ietf.org, nwcrg@irtf.org
In-Reply-To: <152662627753.1538.3506303682099297675@ietfa.amsl.com>
Message-Id: <9ACF3E21-8A26-4C74-843C-1716A95C9F3C@inria.fr>
X-Mailer: Apple Mail (2.3445.6.18)
Archived-At: <https://mailarchive.ietf.org/arch/msg/tsvwg/Jiqq63T3eAlS6MzBKQ2raszsLuM>
Subject: Re: [tsvwg] I-D Action: draft-ietf-tsvwg-rlc-fec-scheme-04.txt
X-BeenThere: tsvwg@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Transport Area Working Group <tsvwg.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tsvwg>, <mailto:tsvwg-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tsvwg/>
List-Post: <mailto:tsvwg@ietf.org>
List-Help: <mailto:tsvwg-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tsvwg>, <mailto:tsvwg-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 18 May 2018 07:13:21 -0000

Dear all,

Here is an updated version of our I-D.

- It takes into accounts comments received by Jonathan Detchart
  (added section 3.6. Finite Fields Operations);

- Section 3.1. Possible Parameter Derivations 
  has been significantly improved for more precision;

- It also fixes a small bug (in parameter checks) in 
  section 3.5.  Coding Coefficients Generation Function;

We are not sure we will keep the current PRNG...
Even with the previous fix (i.e., ignoring the first value produced),
the Park-Miler minimal standard PRNG behaves badly when used
with seeds that are in sequence (e.g., the application generates
a repair symbol with seed s and then s+1, etc.) and when mapping
the PRNG output to a small range of value (especially with [0, 15]):
	Ij+1 = A * s (modulo M)
and:
	Ij+1 = A * (s+1) (modulo M)
scaled to [0, 15] have a certain probability to give the same value.
We are  currently experimenting with alternatives. Unfortunately we
only identified this side-effect recently. 

Cheers,

   Vincent and Belkacem


> Le 18 mai 2018 à 08:51, internet-drafts@ietf.org a écrit :
> 
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Transport Area Working Group WG of the IETF.
> 
>        Title           : Sliding Window Random Linear Code (RLC) Forward Erasure Correction (FEC) Schemes for FECFRAME
>        Authors         : Vincent Roca
>                          Belkacem Teibi
> 	Filename        : draft-ietf-tsvwg-rlc-fec-scheme-04.txt
> 	Pages           : 31
> 	Date            : 2018-05-17
> 
> Abstract:
>   This document describes two fully-specified Forward Erasure
>   Correction (FEC) Schemes for Sliding Window Random Linear Codes
>   (RLC), one for RLC over GF(2) (binary case), a second one for RLC
>   over GF(2^^8), both of them with the possibility of controlling the
>   code density.  They can protect arbitrary media streams along the
>   lines defined by FECFRAME extended to sliding window FEC codes.
>   These sliding window FEC codes rely on an encoding window that slides
>   over the source symbols, generating new repair symbols whenever
>   needed.  Compared to block FEC codes, these sliding window FEC codes
>   offer key advantages with real-time flows in terms of reduced FEC-
>   related latency while often providing improved packet erasure
>   recovery capabilities.
> 
> 
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-ietf-tsvwg-rlc-fec-scheme/
> 
> There are also htmlized versions available at:
> https://tools.ietf.org/html/draft-ietf-tsvwg-rlc-fec-scheme-04
> https://datatracker.ietf.org/doc/html/draft-ietf-tsvwg-rlc-fec-scheme-04
> 
> A diff from the previous version is available at:
> https://www.ietf.org/rfcdiff?url2=draft-ietf-tsvwg-rlc-fec-scheme-04
> 
> 
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at tools.ietf.org.
> 
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>