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Abstract

Indiscriminated packet discards strongly degrade the quality perceived by end users of MPEG video transmissions. This paper investigates different Quality of Service (QoS) schemes and the tradeoffs of jointly adopting such schemes to improve the delivery quality of an MPEG stream. From an analytical model, we evaluate the impact of frame losses on the quality of MPEG streams and on the waste of network resources. Our assessment considers issues such as the use of redundancy by applying a Forward Error Correction (FEC) scheme to tolerate losses, the changing of the compression factor in MPEG encoding, the unequal protection of MPEG frames in a Differentiated Services environment, and how to evaluate the impact of network losses onto application quality. Results provide predicted bounds on the quality to be expected by end users as well as guidelines on how to take the best advantage from the joint adoption of the investigated QoS schemes.

Keywords  Quality of Service - video communications - MPEG - differentiated services - forward error correction

Artur Ziviani received the B.Sc. degree in Electronics Engineering in 1998 and the M.Sc. degree in Electrical Engineering (with emphasis in Computer Networking) in 1999, both from the Federal University of Rio de Janeiro (UFRJ), Brazil. In December 2003, he received the Ph.D. degree in Computer Science from the University Pierre et Marie Curie (Paris 6), Paris, France, where he has also been a lecturer during the 2003–2004 academic year. Since September 2004, he is with the National Laboratory for Scientific Computing (LNCC), located in Petr'opolis, Brazil. His major research interests are quality of service, mobile and wireless computing, Internet measurements, and grid computing.
Bernd E. Wolfinger has been with the Computer Science Department of Hamburg University since 1981, where he is presently heading the Telecommunications and Computer Networks (TKRN) Subdivision. He has degrees from Universit Claude-Bernard, Lyon (Matrise, 74), University of Karlsruhe (Diploma, Mathematics 75; Ph.D., Comp. Sc. 79) and has spent long-term sabbaticals at IBM Research, Yorktown Heights, N.Y. (85), Internat. Computer Science Institute, Berkeley, Ca. (91,96), as well as at Universit P. et M. Curie, Paris (01). Dr. Wolfinger is active in Networking research since 1975, has been responsible for numerous conference organizations and has served on a variety of TPCs. He has been an editor of books and special issues of journals and has published more than 100 papers in areas such as High-speed & Mobile Networks, Real-time Communications, Traffic Engineering, Modeling, Performance Evaluation and QoS Management.
Jos'e Ferreira de Rezende received the B.Sc. and M.Sc. degrees in Electronic Engineering from the Universidade Federal do Rio de Janeiro (UFRJ) in 1988 and 1991, respectively. He received the Ph.D. degree in Computer Science from the Universit Pierre et Marie-Curie, Paris, France in 1997. He was an associate researcher at LIP6 (Laboratoire drsquoInformatique de Paris 6) during 1997. Since 1998 he is an Associate Professor at UFRJ. His research interests are in distributed multimedia applications, multipeer communication, performance evaluation and QoS aspects of high-speed, wireless and sensor networks.
Otto Carlos M.B. Duarte was born in Rio de Janeiro, Brazil, on October 23, 1953. He received the Electronic Engineer degree and the M.Sc. degree in Electrical Engineering from Universidade Federal do Rio de Janeiro, Brazil, in 1976 and 1981, respectively, and the Dr. Ing. degree from ENST/ Paris, France, in 1985. Since 1978 he is a Professor at Universidade Federal do Rio de Janeiro. From January 1992 to June 1993 he has worked at MASI Laboratory in Paris 6 University. In 1995, he has spent three months at International Computer Science Institute (ICSI) associated to the University of California at Berkeley. Presently, he is heading the computer network group (Grupo de Teleinformitica e Automao—GTA). His major research interests are in high speed communications, mobility, security and QoS guarantees.
Serge Fdida is a professor at the University Pierre et Marie Curie (Paris) since 1991. He received the Doctorat de 3eme Cycle in 1984, and the Habilitation a Diriger des Recherches specializing in Modelling of computer networks in 1989 from the University Pierre et Marie Curie. From 1989 to 1995, he was a Full Professor to the University Rene Descartes (Paris). His research interests are in the area of high speed networking, pervasive communication, resource management and performance analysis. He is heading the Network and Performance group of the LIP6 Laboratory (CNRS-University of Paris 6). He was a Visiting Scientist at IBM Research during the 1990/91 academic year. He was the chairman (or co-chair) of the following events: IFIP Modelling Techniques and Tools 87, IFIP High Performance Networking 94 (HPN 94), Performance of Data Communication 95 (PCN 95) and European Conference on Multimedia Applications, Services and Techniques 97 (ECMAST 97), Networked Group Communication (NGC 99) and IFIP Networking 2000. He was the editor of the proceedings of these conferences and is the author of a book on performance evaluation and a book on Networking. He is involved in many research projects in High Performance Networking in France and Europe. He was heading the RHDM Action in France for 8 years and the COST264 Action in Europe (98 02). He belongs to the FP6 network of Excellence ENEXT. He is a senior member of IEEE, a member of ACM and also involved in two IFIP working groups on networking. He is also the Co-Director of EURONETLAB, a joint laboratory established in 2001, between University Paris 6, CNRS, THALES and 6WIND, developing research and development work on QoS Routers and Radio Routers.

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