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
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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 2011Table 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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