Smartphone Advance Can Improve Efficiency, Extend Battery

Researchers at University of Michigan in Ann Arbor have devised a more efficient “idle mode” for smartphones and Wi-Fi devices that reduces power use and can extend battery life. Computer science and engineering professor Kang Shin and doctoral student Xinyu Zhang will present their discovery, still in proof-of-concept stage, next week at the ACM International Conference on Mobile Computing and Networking in Las Vegas.

Shin and Zhang’s invention, called Energy-Minimizing Idle Listening or E-MiLi, reduces the device’s energy consumption while waiting for incoming calls or data. In previous work, they showed that phones in idle listening mode expend roughly the same amount of power as they do when they’re fully awake. In their new research, Shin and Zhang conducted a trace-based analysis of real Wi-Fi networks, which demonstrated that devices in power-saving modes spend 60 to 80 percent of their time in idle listening, depending on the amount of traffic in the network .

This extensive block of idle time then offers an opportunity to significantly reduce a device’s use of power. During this period, E-MiLi slows down the Wi-Fi card’s clock by up to about six percent of its normal frequency, but brings it back to full speed when the device starts receiving data.

To wake up from this deep-idle mode requires the phone or device to read the data or call’s standard header field that has the device’s unique address. Shin and Zhang have developed firmware to enable phones and Wi-Fi devices to encode the message headers for detection by receiving units.

For E-MiLi to get traction, chip makers would need to add these firmware changes in their mobile device chipsets, and manufacturers would need to adopt these chipsets in their devices. Shin says devices supporting E-MiLi would still work with older or non-enabled smartphones.

The research by Shin and Zhang was funded by the National Science Foundation. The university is pursuing patent protection for their discovery, and seeks commercialization partners to help bring the technology to market.

Read more: Engineers Develop Wireless Spectrum-Sensing Algorithms

Photo: Richard Smith/Flickr

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