Plenary Lecture

A survey of playout delay algorithms for interactive applications on the Internet

Professor Victor Ramos R.
Head of the Electrical Engineering Department
Metropolitan Autonomous University (UAM)
San Rafael Atlixco 186, Col. Vicentina,
09340 Mexico City, Mexico
E-Mail: vicman@xanum.uam.mx

Abstract: Interactive audio applications are now widely used in the Internet. Such applications require receiver playout buffers to smooth network delay variations and to reconstruct the periodic form of the transmitted packets. Packetsarriving after their playout deadline are considered late and are not played out. We will explore in this talk three classes of playout delay control algorithms that are used in the Internet. The first class of algorithms sets a fixed deadline for all the arriving packets at the receiver. The second class of algorithms, proposed originally by Henning Schulzrinne and later by Ramachandran Ramjee, operate by adaptively adjusting the playout delay from talkspurt to talkspurt. Finally, the third class of algorithms adjusts the playout delay of each packet on the fly by using a technique called WSOLA. This latter class of algorithms allows to play out packets almost as they arrive with little distortion which is not perceived by the human ear. This mechanism allows to reduce the average playout delay as well as the loss rate due to late packets during an audio session. In this talk, we will compare the three different classes of playout algorithms cited above. We conclude by discussing current research directions on this topic.

Short Biography of the Speaker:
Victor Ramos received the DEA degree (the french equivalent of the master degree) in Networks and Distributed Systems and the PhD degree in Computer Science, both from the University of Nice-Sophia Antipolis, France, in 2000 and 2004 respectively. From 2000 to 2003, he was assistant professor at Institut Eurecom, IAAI Marseille and UNSA in France. Since 1995, he is professor at the Metropolitan Autonomous University (UAM), in Mexico. At UAM, Prof. Ramos has been the Head of the Networks and Telecommunications Research Team, from 2005 to 2007, and since march 2007, he is the Head of the Electrical Engineering Department.

Prof. Ramos has been reviewer for several international conferences and journals like IEEE Infocom, IEEE Globecom, Sigmetrics, Transactions on Networking, Journal on Selected Areas in Communications, Computer Networks, IEEE Transactions on Wireless Communications. He has also been part of the TPC of IEEE Globecom, ICEEE and VCM. Victor Ramos is the author of research papers published at IEEE Infocom, QEST, IWQoS, QofIS and ICEIS. The main research interests of Prof. Ramos are in Performance Evaluation of Computer Protocols, Pricing on the Internet and Peer-to-Peer Networks.