HTTP adaptive streaming in mobile networks: characteristics and caching opportunities

International audienceCellular networks have witnessed the emergence of the HTTP Adaptive Streaming (HAS) as a new video delivery method. In HAS, several qualities of the same videos are made available in the network so that clients can chose the best quality that fits their bandwidth capacity. This has particular implications on caching strategies with respect to the viewing patterns and the switching behavior between video qualities. In this paper we present analysis of a real HAS dataset collected in France and provided by the country's largest mobile phone operator. Firstly, we analyse the viewing patterns of HAS contents and the distribution of the encoding bitrates requested by mobile clients. Secondly, we give an in-depth analysis of the switching pattern between video bitrates during a video session and assess the implication on the caching efficiency. We also model this switching based on empirical observations. Finally, we propose WA-LRU a new caching algorithm tailored for HAS contents and compare it to the standard LRU. Our evaluations demonstrate that WA-LRU performs better and achieves its goals