Self-Clocked Rate Adaptation for Multimedia
RFC 8298

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Internet Engineering Task Force (IETF)                      I. Johansson
Request for Comments: 8298                                     Z. Sarker
Category: Experimental                                       Ericsson AB
ISSN: 2070-1721                                            December 2017

              Self-Clocked Rate Adaptation for Multimedia

Abstract

   This memo describes a rate adaptation algorithm for conversational
   media services such as interactive video.  The solution conforms to
   the packet conservation principle and uses a hybrid loss-and-delay-
   based congestion control algorithm.  The algorithm is evaluated over
   both simulated Internet bottleneck scenarios as well as in a Long
   Term Evolution (LTE) system simulator and is shown to achieve both
   low latency and high video throughput in these scenarios.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  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).  Not
   all documents approved by the IESG are a candidate for any level of
   Internet Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8298.

Johansson & Sarker            Experimental                      [Page 1]
RFC 8298                         SCReAM                    December 2017

Copyright Notice

   Copyright (c) 2017 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
   (https://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.

Johansson & Sarker            Experimental                      [Page 2]
RFC 8298                         SCReAM                    December 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Wireless (LTE) Access Properties  . . . . . . . . . . . .   4
     1.2.  Why is it a self-clocked algorithm? . . . . . . . . . . .   5
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   5
   3.  Overview of SCReAM Algorithm  . . . . . . . . . . . . . . . .   6
     3.1.  Network Congestion Control  . . . . . . . . . . . . . . .   8
     3.2.  Sender Transmission Control . . . . . . . . . . . . . . .   9
     3.3.  Media Rate Control  . . . . . . . . . . . . . . . . . . .   9
   4.  Detailed Description of SCReAM  . . . . . . . . . . . . . . .  10
     4.1.  SCReAM Sender . . . . . . . . . . . . . . . . . . . . . .  10
       4.1.1.  Constants and Parameter Values  . . . . . . . . . . .  10
         4.1.1.1.  Constants . . . . . . . . . . . . . . . . . . . .  11
         4.1.1.2.  State Variables . . . . . . . . . . . . . . . . .  12
       4.1.2.  Network Congestion Control  . . . . . . . . . . . . .  14
         4.1.2.1.  Reaction to Packet Loss and ECN . . . . . . . . .  17
         4.1.2.2.  Congestion Window Update  . . . . . . . . . . . .  17
         4.1.2.3.  Competing Flows Compensation  . . . . . . . . . .  20
         4.1.2.4.  Lost Packet Detection . . . . . . . . . . . . . .  22
         4.1.2.5.  Send Window Calculation . . . . . . . . . . . . .  23
         4.1.2.6.  Packet Pacing . . . . . . . . . . . . . . . . . .  24
         4.1.2.7.  Resuming Fast Increase Mode . . . . . . . . . . .  24
         4.1.2.8.  Stream Prioritization . . . . . . . . . . . . . .  24
       4.1.3.  Media Rate Control  . . . . . . . . . . . . . . . . .  25
     4.2.  SCReAM Receiver . . . . . . . . . . . . . . . . . . . . .  28
       4.2.1.  Requirements on Feedback Elements . . . . . . . . . .  28
       4.2.2.  Requirements on Feedback Intensity  . . . . . . . . .  30
   5.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .  31
   6.  Suggested Experiments . . . . . . . . . . . . . . . . . . . .  31
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  32
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  32
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  33
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  33