Ra-MobiSys10 - Energy-Delay Tradeoffs in Smartphone...

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Unformatted text preview: Energy-Delay Tradeoffs in Smartphone Applications * Moo-Ryong Ra Jeongyeup Paek Abhishek B. Sharma Ramesh Govindan Martin H. Krieger * Michael J. Neely Computer Science Dept. School of Policy, Planning, and Development * Electrical Engineering Dept. University of Southern California, Los Angeles, CA, USA {mra, jpaek, absharma, ramesh, krieger, mjneely} @ usc.edu ABSTRACT Many applications are enabled by the ability to capture videos on a smartphone and to have these videos uploaded to an Internet- connected server. This capability requires the transfer of large vol- umes of data from the phone to the infrastructure. Smartphones have multiple wireless interfaces 3G/EDGE and WiFi for data transfer, but there is considerable variability in the availability and achievable data transfer rate for these networks. Moreover, the en- ergy costs for transmitting a given amount of data on these wireless interfaces can differ by an order of magnitude. On the other hand, many of these applications are often naturally delay-tolerant, so that it is possible to delay data transfers until a lower-energy WiFi connection becomes available. In this paper, we present a prin- cipled approach for designing an optimal online algorithm for this energy-delay tradeoff using the Lyapunov optimization framework. Our algorithm, called SALSA, can automatically adapt to channel conditions and requires only local information to decide whether and when to defer a transmission. We evaluate SALSA using real- world traces as well as experiments using a prototype implementa- tion on a modern smartphone. Our results show that SALSA can be tuned to achieve a broad spectrum of energy-delay tradeoffs, is closer to an empirically-determined optimal than any of the alter- natives we compare it to, and, can save 10-40% of battery capacity for some workloads. Categories and Subject Descriptors C.4 [ Performance of Systems ]: Design Studies Energy Manage- ment on Smartphones * This research was sponsored by the USC/CSULB METRANS Trans- portation Center and by the Army Research Laboratory under Cooperative Agreement Number W911NF-09-2-0053. The views and conclusions con- tained in this document are those of the authors and should not be inter- preted as representing the official policies, either expressed or implied, of the METRANS center, the Army Research Laboratory or the U.S. Gov- ernment. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation hereon. In addition, the first author, Moo-Ryong Ra, was supported by An- nenberg Graduate Fellowship. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific...
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This note was uploaded on 08/25/2011 for the course EEL 6788 taught by Professor Boloni,l during the Spring '08 term at University of Central Florida.

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Ra-MobiSys10 - Energy-Delay Tradeoffs in Smartphone...

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