Self-Clocked Rate Adaptation for Multimedia
RFC 8298
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
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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
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