Quality-Aware Cooperative Proxy Caching for Video Streaming Services
By applying a proxy mechanism widely used in WWW systems to video streaming systems, low-delay and high-quality video distribution can be accomplished without imposing extra load on the system. The video streaming system proposed in this paper consists of a video server and multiple proxy servers. In our mechanism, proxies communicate with each other and retrieve missing video data from an appropriate server by taking into account transfer delay and offerable quality. In addition, the quality of cached video data is adapted appropriately at a proxy to cope with the client-to-client heterogeneity in terms of the available bandwidth, end-system performance, and user preferences on the perceived video quality. Through simulation experiments, it is shown that our proposed mechanism can provide users with low-delay and highquality video streaming services. Furthermore, to verify our mechanism, we implement a real system for MPEG-4 video streaming services and show that our proxy caching system can provide users with a continuous video distribution under dynamically changing network conditions.