Video on Demand will be one of the dominant payload types both in fixed and mobile networks. In the absence of multicast support from the network, traditional client-server based architectures require at least linear scaling of the server capacity. In this talk, I will present a hybrid video on demand (VoD) system that combines CDN type infrastructure with P2P delivery. Such hybrid systems combine the reliability and availability of CDN with the scalability of P2P delivery. In the proposed system, each video file is chopped into a number of segments and video clients (i.e., peers) are allowed to cache only one segment at a time. When peer service capacity lags behind the overall demand, the excess demand is compensated by the CDN servers. A central controller regulates the peering decisions as well as decides on the use of peer upload bandwidth and cache space by solving a supply-demand based optimization problem. In the first part of the talk, I will provide more details on the proposed architecture and show the performance results in comparison with various alternative solutions. In the second part, I will present how we can incorporate scalable video into our hybrid architecture under limited server bandwidth scenarios. As time permits, in the final part of the talk, I will provide a synopsis of our current efforts in terms of proto-typing and integration with an elastic computing facility.

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Ulas C. Kozat is a senior researcher and project manager at DOCOMO USA Labs located in Palo Alto, CA. He received his Ph.D. degree in 2004 from the Department of Electrical and Computer Engineering at the University of Maryland, College Park. He conducted research under the Institute for Systems Research (ISR) and Center for Hybrid and Satellite Networks (CSHCN) at the same university. He also worked at HRL Laboratories and Telcordia Technologies Applied Research as research intern during the same period. He received his M.S. degree in Electrical Engineering from the George Washington University, Washington, DC and his B.S. degree in Electrical and Electronics Engineering from Bilkent University, in 1999 and 1997, respectively. He has conducted research in the broad areas of wireless communications and communication networks. He has published mainly on cross-layer optimization, network modeling and performance analysis, and algorithm/protocol design.