This document is an optional Building Block usable to fully define
an RMT Transport Protocol. It fully-specifies a Forward Error
Correction Code, called "RaptorQ", within the guidelines of
RFC 5052. It also specifies procedures and
packet-header fields, as required by RFC 5052.
The combination of this document and RFC 5052 allows the
implementation of an interoperable Forward Error Correction
scheme usable in the context of an RMT transport protocol (e.g.
LCT/ALC or NORM).
RaptorQ is a fountain code, i.e., as many encoding symbols
as needed can be generated by the encoder on-the-fly from the
source symbols of a source block of data. The decoder is able to
recover the source block from any set of encoding symbols only
generally equal to or occasionally with slightly more in number
than the number of source symbols.
The RaptorQ code described here is a systematic code, meaning that all
the source symbols are among the encoding symbols that can be generated
Working Group Summary
There is consensus in the WG to publish these documents.
As a result of the IESG questions and discussions, a further revised IPR
statement was filed by Qualcomm Incorporated. See the following link:
Because of this updated IPR disclosure, an additional RMT Working Group Last Call
was conducted. The only resultant working group email discussion to the revised IPR
was that it was an improvement in that it more clearly covered unicast as well as
multicast use cases of the technology. The following URL points to the mailing
list archive message thread regarding this additional WGLC:
It is important to note, as had been described in the earlier publication writeup for
this specification that, although IPR is in place, this forward error correction
technique is just one of several types that the RMT WG has specified and other,
unencumbered techniques have been defined. Thus, the RMT WG had previously discussed
this matter concluding that it wished to publish this document regardless of the IPR
since this new FEC code is one of multiple alternatives that can be used to implement
the RMT higher-level protocols, as such the possible IPR covering this does not
preclude the unencumbered implementation of the RMT Protocols. The IPR licensing terms presented by Qualcomm appear to be reasonable.
Are there existing implementations of the protocol? Have a
significant number of vendors indicated their plan to
implement the specification? Are there any reviewers that
merit special mention as having done a thorough review,
e.g., one that resulted in important changes or a
conclusion that the document had no substantive issues? If
there was a MIB Doctor, Media Type, or other Expert Review,
what was its course (briefly)? In the case of a Media Type
Review, on what date was the request posted?
The document is similar in content to the prior "Raptor"
codec of RFC 5053 and benefits from the development and reviews
of that specification. Additionally, an independent implementation
was conducted from the version 03 draft and only minor suggestions
were made (and were incorporated) by that developer to clarify the document.
Document Shepherd: Brian Adamson (email@example.com)
Responsible Area Director: David Harrington