Cache Replacement Techniques for Streaming Media in Wireless Home Networks

Wireless home networks are widely deployed due to their low cost, ease of installation, and plug-and-play capabilities with consumer electronic devices. Participating devices may cache continuous media (audio and video clips) in order to reduce the demand for outside-the-home network resources and improve the average delay incurred from when a user references a clip to the onset of its display (startup latency). In this paper, we focus on a home network consisting of a handful of devices. A device may manage its cache at the granularity of either a clip or individual blocks of a clip by employing either a clip-based or a block-based cache replacement technique. It may employ a technique in either stand-alone mode to enhance a local metric such as cache hit rate or make its state dependent on other devices in the home network to enhance a global metric such as average startup latency. These two variants are named greedy and cooperative, respectively. The primary contribution of this paper is to evaluate these alternatives using realistic specifications of a wireless home network. Our key finding is as follows. Our proposed cooperative block-based technique enhances startup latency when compared with clip-based alternatives. With multiple devices where each device acts greedy, clip-based caching is superior. In addition, we show our proposed block-based replacement policy materializes appropriate fraction of each clip across devices dynamically, eliminating the need to compute and place prefetch portions statically.