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RaptorQ Forward Error Correction Scheme for Object Delivery
RFC 6330

Internet Engineering Task Force (IETF)                           M. Luby
Request for Comments: 6330                         Qualcomm Incorporated
Category: Standards Track                                 A. Shokrollahi
ISSN: 2070-1721                                                     EPFL
                                                               M. Watson
                                                            Netflix Inc.
                                                          T. Stockhammer
                                                          Nomor Research
                                                               L. Minder
                                                   Qualcomm Incorporated
                                                             August 2011

      RaptorQ Forward Error Correction Scheme for Object Delivery

Abstract

   This document describes a Fully-Specified Forward Error Correction
   (FEC) scheme, corresponding to FEC Encoding ID 6, for the RaptorQ FEC
   code and its application to reliable delivery of data objects.

   RaptorQ codes are a new family of codes that provide superior
   flexibility, support for larger source block sizes, and better coding
   efficiency than Raptor codes in RFC 5053.  RaptorQ is also a fountain
   code, i.e., as many encoding symbols as needed can be generated on
   the fly by the encoder from the source symbols of a source block of
   data.  The decoder is able to recover the source block from almost
   any set of encoding symbols of sufficient cardinality -- in most
   cases, a set of cardinality equal to the number of source symbols is
   sufficient; in rare cases, a set of cardinality slightly more than
   the number of source symbols is required.

   The RaptorQ code described here is a systematic code, meaning that
   all the source symbols are among the encoding symbols that can be
   generated.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

Luby, et al.                 Standards Track                    [Page 1]
RFC 6330                   RaptorQ FEC Scheme                August 2011

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6330.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Luby, et al.                 Standards Track                    [Page 2]
RFC 6330                   RaptorQ FEC Scheme                August 2011

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Requirements Notation  . . . . . . . . . . . . . . . . . . . .  4
   3.  Formats and Codes  . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . .  5
     3.2.  FEC Payload IDs  . . . . . . . . . . . . . . . . . . . . .  5
     3.3.  FEC Object Transmission Information  . . . . . . . . . . .  5
       3.3.1.  Mandatory  . . . . . . . . . . . . . . . . . . . . . .  5
       3.3.2.  Common . . . . . . . . . . . . . . . . . . . . . . . .  5
       3.3.3.  Scheme-Specific  . . . . . . . . . . . . . . . . . . .  6
   4.  Procedures . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . .  7
     4.2.  Content Delivery Protocol Requirements . . . . . . . . . .  7
     4.3.  Example Parameter Derivation Algorithm . . . . . . . . . .  7
     4.4.  Object Delivery  . . . . . . . . . . . . . . . . . . . . .  9
       4.4.1.  Source Block Construction  . . . . . . . . . . . . . .  9
       4.4.2.  Encoding Packet Construction . . . . . . . . . . . . . 11
       4.4.3.  Example Receiver Recovery Strategies . . . . . . . . . 12
   5.  RaptorQ FEC Code Specification . . . . . . . . . . . . . . . . 12

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