An intelligent satellite multicast and caching overlay for CDNs to improve performance in video applications

Over the past decade, video has become the dominant form of traffic consumed over content delivery networks (CDNs). This trend, coupled with the ever-increasing subscriber base, has caused an explosion of data demands in a wide variety of scenarios. Such trends have resulted in heightened levels of congestion within today's terrestrial networks and are expected to become more acute in the coming years. To combat network congestion, we propose a satellite-based overlay for existing terrestrial CDNs. Satellite networking has distinct advantages over terrestrial networks in being able to distribute delay-tolerant high bandwidth content across a wide geographic area simultaneously, with few limitations to the distance between requestor and source, nor the number of locations being served. Additionally, our solution calls for cache storage at local proxy servers one-hop from the end users, which in most instances will improve the response time of current network architectures. The proposed cache algorithm leverages the homogeneous coverage area provided by satellite to allow each proxy server to compare its local network view to the global picture, learn the popularity distributions quickly, and make its own caching decisions. Through simulations of two CDN case studies-Cellular and Video on Demand-we find that multicasting can provide significant reductions in required network bandwidth as compared to terrestrial-based unicast, for situations dominated by video traffic. Further, by leveraging advantages offered by our caching algorithm, we show that the multicast solution scales well, both with increasing cache storage and coverage area. Our solution appears robust as relevant traffic parameters, such as heavy-tail characteristics and global file popularity, are varied. The work presented in this paper is the result of an ongoing collaboration between Princeton University and SES. We believe that our solution incorporates the technologies best suited for the networking challenges being faced today and is forward looking in its ability to scale with demand, content type and size, which enables new market opportunities for the satellite industry.