1Multimedia Proxy Caching Mechanism for Quality Adaptive Streaming Applications in the Internet

Abstract — The Internet has witnessed a rapid growth in deployment of Web-based streaming applications during re-cent years. In these applications, server should be able to perform end-to-end congestion control and quality adapta-tion to match the delivered stream quality to the average available bandwidth. The delivered quality is limited by the bottleneck bandwidth on the path to the client. This paper proposes a proxy caching mechanism for layered-encoded multimedia streams in the Internet to max-imize the delivered quality of popular streams to interested clients. The main challenge is to replay a quality-variable cached stream while performing quality adaptation effec-tively in response to the variations in available bandwidth. We present a pre-fetching mechanism to support higher quality cached streams during subsequent playbacks and improve the quality of the cached stream with its popular-ity. We exploit inherent properties of multimedia streams to extend the semantics of popularity and capture both level of interest among clients and usefulness of a layer in the cache. We devise a fine-grain replacement algorithm suited for layered-encoded streams. Our simulation results show that the interaction between the replacement algorithm and pre-fetching mechanism causes the state of the cache to con-verge to an efficient state such that the quality of a cached stream is proportional to its popularity, and the variations in quality of a cached stream are inversely proportional to its popularity. This implies that after serving several requests for a stream, the proxy can effectively hide low bandwidth paths to the original server from interested clients