My work on smartphone handsets focusses on software interventions to prolog battery life. The principle goal is make sure that mobile software and applications have a minimal energy impact.
We built a testbed for making direct measurements of the phone power consumption. This works by intercepting the current flowing from the battery with a high-precision sense resistor. We sample the voltage across the battery and the voltage drop across this resistor to derive power consumption. Our hardware samples at 250Khz which is sufficient fidelity to see frames sent over the wireless interface.
The significance of many power savings depends on the real-world use of handsets. However, there is a lack of any large scale data set, up-to-date data set of smart phone use. The Device Analyzer project is our attempt to answer that need. We are aiming to build such a data set and then share it with research community. We collect the data using a free application available on the Android application store and have so far amassed data from more than 10,000 people world-wide. For some of these users we now have more than 12 months of information. We'll be publishing a paper describing our work in tandem with the data set. Please contact me if you'd like to be kept informed.
Mobile phones are complicated multi-layer devices and its often very hard to work out exactly what behaviour is being triggered on the device. We are currently investigating instrumentation approaches for mobile devices to allow us to analyze this behaviour better and to better control our experiments.
There is lots of advice for programmers for energy optimisation but it often requires significant expertise to understand it and apply it. In this project we are attempting to codify energy saving advice, check its validity and integrate it into the development process.