Colin Perkins

Alvaro Saurin — Congestion Control for Video-conferencing Applications

Posted on 15 December 2006 in category cc

Congratulations to Alvaro Saurin, who has completed his MSc thesis on Congestion Control for Video-conferencing Applications, looking into how well TCP-Friendly Rate Control (TFRC) works on real-world networks. The abstract reads:

In the Internet, transmission systems must deal with congestion in order to keep the stability of the network. However, the model used for congestion control determines some important properties of the traffic. The most important algorithm currently used, found in the TCP protocol, has characteristics that make it unsuitable for videoconferencing systems.

The aim of this dissertation is to provide an insight into the field of congestion control for such systems. In particular, this work examines one of the most promising alternatives available, TCP-Friendly Rate Control (TFRC), to answer the question “is TFRC suitable for interactive videoconferencing applications?”

This dissertation presents the results obtained with TFRC, focusing on some practical aspects and providing recommendations for the implementation of such a rate-based congestion control system. This work examines the scenarios where TFRC is an adequate solution, exposing the behavior that can be expected and suggesting future improvements.

The thesis also presents the experiences of integrating TFRC in the UltraGrid videoconferencing application. It shows the difficulties found, demonstrating that this integration requires an significant amount of support from the application, and questioning the suit- ability of TFRC in some situations.

This works was completed as part of the NSF-funded UltraGrid project.

• Alvaro Saurin, Congestion Control for Video-conferencing Applications, MSc Thesis, University of Glasgow, December 2006.

New research student: Alvaro Saurin

Posted on 01 December 2004 in category cc

Welcome to Alvaro Saurin, who will be working on integration of TCP Friendly Rate Control (TFRC) with high performance interactive video, as part of the UltraGrid project.

Congestion Control for Real-Time Media

Posted on 13 February 2002 in category cc

Provision of congestion control is a significant open issue for interactive real-time networked multimedia systems. Numerous congestion control algorithms have been proposed, but they frequently conflict with the demands of interactive multimedia applications. My paper “Building Adaptive Applications: On The Need For Congestion Control” (an invited paper presented at the 17th SPIE/IS&T International Symposium on Electronic Imaging, San Jose, CA, USA, January 2005) outlines some of the issues.

My research has focussed on the effects of jitter and reordering on congestion controlled transport protocols, on TCP friendly rate control, and on the integration of real time applications with the Datagram Congestion Control Protocol (DCCP).

Effects of Jitter and Reordering

Evaluation of the effects of network timing jitter and packet reordering on multimedia applications. Design of congestion control protocols to decouple response to loss and reordering. Comparison with TCP and TCP-Friendly Rate Control.

• Ladan Gharai, Colin Perkins and Tom Lehman, Packet Reordering, High Speed Networks and Transport Protocol Performance, Proceedings of the 13th International Conference on Computer Communications and Networks (ICCCN'04), Chicago, IL, USA, October 2004. DOI:10.1109/ICCCN.2004.1401591
• Ladan Gharai and Colin Perkins, Implementing Congestion Control in the Real World, Proceedings of the IEEE International Conference on Multimedia and Expo, Lausanne, Switzerland, August 2002. DOI:10.1109/ICME.2002.1035802

RTP over DCCP

Developing a mapping of the Real-time Transport Protocol (RTP) onto the Datagram Congestion Control Protocol (DCCP).

• Colin Perkins, RTP and the Datagram Congestion Control Protocol (DCCP), Internet Engineering Task Force, June 2007, Work in progress (draft-ietf-dccp-rtp-07).
• Colin Perkins and Ladan Gharai, RTP and the Datagram Congestion Control Protocol, Proceedings of the IEEE International Conference on Multimedia and Expo, Toronto, Canada, July 2006. DOI:10.1109/ICME.2006.262832