Energy Efficient Mobile Communication using Cloud Support
Overview
Cellular radio communication is a significant contributor to battery energy drain on smartphones, in some cases adding a factor of 5 or more times the energy cost of the base device. Stratus is a system that leverages resources in the cloud to reduce the energy consumed for data communication on smartphones. Using a cloud-based proxy, Stratus employs optimizations that adapt application’s incoming and outgoing traffic to better match the energy characteristics of the radio interface. The optimizations include an aggregation technique for bunching up sporadic transmissions, an asymmetric dictionary based compression for reducing the number of bits transmitted over the air and an opportunistic scheduling technique for avoiding communication during periods of poor signal reception. These optimizations can be used individually, or in combination, subject to application’s latency requirements. For example, using our Stratus prototype, aggregation and compression optimizations achieves up to 50% energy savings for web browsing, while aggregation and scheduling optimizations achieves up to 35% energy savings for a media streaming application.
Stratus Optimizations
Aggregation: Cellular communication exhibits an “energy tail”. Bursty communication helps amortize this overhead [part of ACM CoNext 2009]
Compression: Employ an asymmetric, lossless, dictionary-based redundancy elimination technique, with minimal decompression overhead – bandwidth savings translate to equivalent energy savings on clients [part of USENIX NSDI 2010]
Scheduling: Significant difference in energy draw between communication at good and bad signal locations. Schedule communication at best signal locations, subject to application latency requirements, leveraging cellular signal strength profiles and mobility prediction. [ACM Mobicom 2010]