Greedy Cache Management Techniques for Mobile Devices

Mobile devices are configured with one or more wireless cards that provide limited radio-range and unreliable transmission. These energy-constrained devices are configured with a fixed amount of storage. A device may set aside a fraction of its local storage as a cache to minimize use of the network when servicing requests, enhancing metrics such as startup latency and data availability. In this paper, we focus on a repository of continuous media (audio and video) clips and study several greedy cache management techniques and their cache hit rates. This metric reflects what percentage of requests for clips is serviced when a mobile device is disconnected from the network. The device becomes network detached due to factors such as residing in a densely populated geographical location with over committed network bandwidth or travels to geographical areas with no base station coverage. We investigate repositories of both equisized and variable-sized clips, identifying limitations of the current techniques. Our primary contribution is development of three novel techniques to address these limitations. They are adaptable and provide competitive cache hit rates. One technique, called Dynamic Simple, provides a higher-cache hit rate and adapts faster to changing patterns of access to clips when compared with other techniques.