TAILIEUCHUNG - An Analysis of Power Consumption in a Smartphone

Despite its importance, prior work on event causality extraction in context in the NLP litera- ture is relatively sparse. In (Girju, 2003), the au- thor used noun-verb-noun lexico-syntactic patterns to learn that “mosquitoes cause malaria”, where the cause and effect mentions are nominals and not nec- essarily event evoking words. In (Sun et al., 2007), the authors focused on detecting causality between search query pairs in temporal query logs. (Beamer and Girju, 2009) tried to detect causal relations be- tween verbs in a corpus of screen plays, but limited themselves to consecutive, or adjacent verb pairs. In (Riaz and Girju, 2010), the authors first cluster sentences into topic-specific scenarios, and then fo- cus on. | An Analysis of Power Consumption in a Smartphone Aaron Carroll NICTA and University of New South Wales Gernot Heiser NICTA University of New South Wales and Open Kernel Labs gernot@ Abstract Mobile consumer-electronics devices especially phones are powered from batteries which are limited in size and therefore capacity. This implies that managing energy well is paramount in such devices. Good energy management requires a good understanding of where and how the energy is used. To this end we present a detailed analysis of the power consumption of a recent mobile phone the Openmoko Neo Freerunner. We measure not only overall system power but the exact breakdown of power consumption by the device s main hardware components. We present this power breakdown for micro-benchmarks as well as for a number of realistic usage scenarios. These results are validated by overall power measurements of two other devices the HTC Dream and Google Nexus One. We develop a power model of the Freerunner device and analyse the energy usage and battery lifetime under a number of usage patterns. We discuss the significance of the power drawn by various components and identify the most promising areas to focus on for further improvements of power management. We also analyse the energy impact of dynamic voltage and frequency scaling of the device s application processor. 1 Introduction Mobile devices derive the energy required for their operation from batteries. In the case of many consumerelectronics devices especially mobile phones battery capacity is severely restricted due to constraints on size and weight of the device. This implies that energy efficiency of these devices is very important to their usability. Hence optimal management of power consumption of these devices is critical. At the same time device functionality is increasing rapidly. Modern high-end mobile phones combine the functionality of a pocket-sized communication device with PC-like

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