University of Michigan computer science and engineering professor Kang Shin and doctoral student Xinyu Zhang have developed a power management approach to extend mobile wireless device battery life by up to 54% for users on the busiest networks. The approach is still in the proof-of-concept stage and is not yet commercially available.
The new technology is called E-MiLi, which stands for Energy-Minimising Idle Listening.
After extensive research they concluded devices spend 60 to 80 percent in ‘power-saving’ modes, in idle listening. They found the ‘power-saving’ mode consumes roughly the same amount of power as normal mode.
The E-MiLi technology under-clocks the WiFi card’s clock-speed by up to 1/16 its normal frequency, but jolts it back to full speed when the phone notices information coming in. It’s well known that you can slow a device’s clock to save energy. The hard part, Shin said, was getting the phone to recognize an incoming message while it was in this slower mode.
“We came up with a clever idea,” Shin said. “Usually, messages come with a header, and we thought the phone could be enabled to detect this, as you can recognize that someone is calling your name even if you’re 90 percent asleep.”
When used with power-saving mode, the researchers found that E-MiLi is capable of reducing energy consumption by around 44 percent for 92 percent of mobile devices in real-world wireless networks.
In addition to new processor-slowing software on smartphones, E-MiLi requires new firmware for phones and computers that would be sending messages (software upgrade only). They need the ability to encode the message header—the recipient’s address—in a new and detectable way. The researchers have created such firmware, but in order for E-MiLi use to become widespread, WiFi chipset manufacturers would have to adopt these firmware modifications and then companies that make smartphones and computers would have to incorporate the new chips into their products.
Shin points out that E-MiLi is compatible with today’s models, so messages sent with future devices that use E-MiLi‘s encoding would still be received as usual on smartphones without E-MiLi. E-MiLi can also be used with other wireless communication protocols that require idle listening, such as ZigBee.
This research was funded by the National Science Foundation. The paper is titled “E-MiLi: Energy-Minimising Idle Listening in Wireless Networks.” The university is pursuing patent protection for the intellectual property, and is seeking commercialisation partners to help bring the technology to market.
For more information:
Kang Shin: http://www.eecs.umich.edu/~kgshin/
Full text of conference paper: http://kabru.eecs.umich.edu//papers/publications/2011/xyzhang_kgshin_mobicom11.pdf
