1Motorola Mobility, 600 US Highway 45, Libertyville, IL 60048, USA;
2Faculty of Technical Sciences, UNS, Trg Dositeja Obradovica 6, 21000 Novi Sad, Serbia;
3La Citadelle Inzenjering, Narodnog Fronta 35, 21000 Novi Sad, Serbia;
Content Delivery Networks (CDNs) play an important role in today’s video distribution solutions. While the need for efficient content delivery is well understood, the energy consumption of various video CDN topologies deserves extra attention since energy considerations are increasingly becoming a key performance factor for system designers and operators. This paper investigates the energy efficiency aspect of a special class of video CDN system, namely pervasive wireless CDN based on wireless mesh network implementation. We start by analyzing and defining the energy efficiency of a generic video CDN system. Then we introduce mathematical analysis and simulation model description for wireless CDNs exploring the idea of content placement among wireless access points which serve as local video servers. Computer simulation analysis, based on mixed integer linear programming model, is used to derive “optimal” content placement and caching strategies while minimizing the energy consumption subject to a constraint in terms of the storage size at each mesh router. The objective function of the mathematical model captures the desire to optimize multiple performance factors. In this particular case we are focusing on the QoS/latency time and power consumption. The results demonstrate trade-off dependency between QoS and power consumption. In summary, the paper offers additional insight into the content diffusion strategies as related to a pervasive wireless CDN, and implications of the placement strategies relative to its energy efficiency.
Keywords: Wireless Mesh Network (WMN), energy efficiency, CDN, video streaming, caching, average delivery tree length
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