Caching IPTV

IPTV services are the fastest growing television services in the world today. This is a bandwidth intensive service, requiring low latency and tight control of jitter. To guarantee the quality of service required, service providers opt to multicast all TV channels at all times to everywhere. However, a significant number of channels are rarely watched, which makes this a very inefficient delivery system. In this paper, we present the first caching system for live streaming IPTV. We consider three different caching strategies: caching all TV channels, caching only the active channels, or maintain a fixed-size cache. We have evaluated these different strategies by means of trace-driven simulations using a large dataset from a commercial nationwide IPTV service. The dataset comprises 255 thousand users, 150 TV channels, and covers a 6-month period. The overall conclusion of this study is that we can save a considerable amount of bandwidth affecting only a very small number of TV channel requests. For instance, if the ISP we analysed cached only half the number of TV channels in each DSLAM, thus saving 50% of the bandwidth, it would affect on average only 2% of all requests. Also, by caching only the active channels in regional routers, the bandwidth savings could add up to 33% in most regions, affecting less than 0.2% of all requests.