New Jersey Institute of Technology Department of Electrical and Computer Engineering, New Jersey Center for Multimedia Research Center for Communications and Signal Processing Research North Jersey Chapter of IEEE Communications Society present NETWORKS WITH DETERMINISTIC QUALITY-OF-SERVICE GUARANTEES Professor Jorg Liebeherr University of Virginia January 29, 1997 2:30 PM, ECEC Room 202 Abstract: The most demanding applications in a Quality-of-Service network require a bounded-delay service that provides deterministic(i.e., worst-case) bounds on network latencies for all packets. Since traffic sources may have a variable bit rate (VBR) with a high degree of burstiness, the network must carefully allocate its resources in order to ensure a high achievable network utilization. The talk presents two recent results: (1) a traffic characterization method for VBR video, and (2) a novel scheduler that transmits packets without violating the worst-case delay bounds. The traffic characterization method is designed to accurately specify the traffic of stored VBR video sources, with low computational overhead. Using actual MPEG traces, we demonstrate that using our method achieves higher network utilizations than any other known characterization scheme. We present a new packet scheduling discipline, referred to as Rotating-Priority-Queues+ (RPQ+), that attempts to combine the low implementation overhead of a priority scheduler with the high efficiency of the optimal Earliest-Deadline-First (EDF) scheduler. RPQ+ is the only known packet scheduler that is both superior to a priority scheduler and has an achievable network utilization that increases with queue rotation frequency, approaching that of EDF in the limit. Short Bio: Jorg Liebeherr received the Diplom-Informatiker (M.S.) degree from the University of Erlangen, Germany, in 1988 and the Ph.D. degree in Computer Science from the the Georgia Institute of Technology in 1991. During 1990 and 1991 he did his dissertation work partly at the IBM T. J. Watson Research Center. In 1992 he was a Postdoctoral Fellow in the Computer Science Division at the University of California, Berkeley. Since September 1992 he is an Assistant Professor in the Computer Science Department at the University of Virginia. He received an NSF Research Initiation Award in 1993 and an NSF CAREER Award in 1996.