Real-time transport and adaptation for multimedia traffic over ATM and IP networks

grantor: University of TorontoThe research work in this thesis addresses different issues related to the transport and adaptation for multimedia traffic over ATM and IP networks. We first present a characterization of multimedia applications with respect to their transport architectures and associated Quality of Service (QoS) requirements. In particular, we study the architectural components of Distributed Video Production (DVP) systems, which encompass a variety of multimedia applications with a diverse set of characteristics and QoS requirements. Based on this study, we realize the need for flexible network-level real-time adaptation, in order to deliver the requested QoS on an end-to-end basis. We then focus on real-time transport and QoS adaptation in ATM and IP networks. Both ATM and IP networking technologies attempt to provide QoS-enabled transport for their users. For ATM, we propose an integrated implementation model for ATM Adaptation Layer type 1 (AAL1) with Forward Error Correction (FEC) capabilities. We also propose an enhancement for the AAL1 protocol in order to support Variable Bit Rate (VBR) traffic that exhibits a Piece-wise Constant Bit Rate (PCBR) behavior, such as in the case of VBR MPEG video. We conduct a performance verification study based on a comprehensive simulation model for an end-to-end connection carrying CBR and VBR MPEG video over ATM networks. The results confirm the suitability of our implementation models for typical video applications under different network conditions. We then turn our attention to real-time transport and QoS adaptation in IP networks. We present a novel approach for providing flexible and configurable transport and adaptation functions. In particular, we propose a Generic Real-time transport and Adaptation Protocol (GRAP), which enables IP networks to transport real-time multimedia with a variety of QoS requirements under different network conditions. We explain the features and capabilities provided by GRAP and explain their role in providing QoS for the applications. For a proof of concept, we describe a reference implementation for GRAP in the form of a socket-based Application Programming Interface (API), similar to the popular Berkeley Software Distribution (BSD) sockets programming model. We also demonstrate the use of GRAP sockets by developing a client-server real-time video streaming application. Finally, we perform an experimental performance verification study for GRAP. We describe the methodology of our experimental study and discuss the results obtained. Our experimental results confirm the validity of the GRAP model in achieving its design goals. In particular, we demonstrate the efficiency of the timing recovery and error control schemes in enhancing the overall Quality of Service delivered to the application. We also provide guidelines for the selection of GRAP profiles by studying the effect of different profile parameters on the delivered QoS of the GRAP connection.Ph.D