Variable Rate Caching for Video Delivery in Heterogeneous Environment

Caching video objects at the edge of the back-bone network has become a hot spot in the video delivery research. Some researchers proposed segmentation-based caching algorithms to improve the disk utility in the homogeneous environment. Other researchers proposed caching algorithms with video layering or transcoding to improve the perceptual quality in the heterogeneous environment. However, for a low cost proxy, these systems are suffering from either inflexible structures or high computation. In this paper, the overall quality hit ratio(QHR) is proposed to measure how well the clients´ requests on the quality are satisfied. Aiming to achieve the highest QHR, an intelligent caching algorithm is designed to determine the appropriate perceptual quality of the segments cached in the proxy. This innovative approach takes not only the access bandwidth distribution into account, but also the segment popularity distribution. Simulation results demonstrate that our variable rate caching(VRC) algorithm not only achieves the highest QHR but also keeps its complexity at an acceptable level.