New Invention Puts Smartphones in Half-asleep State, Cuts Down Power Consumption by 44%

September 16, 2011

A professor and a student at the University of Michigan may have found a way to let you squeeze more power out of your smartphones and Wi-Fi-enabled mobile gadgets. The solution is called E-MiLi, which stands for Energy-Minimizing Idle Listening, and which its news release described as a “subconscious mode” for smartphones and other Wi-Fi-powered devices.

Computer science and engineering professor Kang Shin and doctoral student Xinyu Zhang, both of the University of Michigan, worked jointly on E-MiLi. Shin and Zhang’s research found that E-MiLi can cut down energy consumption by about 44% for 92% of mobile devices in real-world wireless networks.

The duo found that smartphones continue to engage in “idle listening” even if the phones are in power-saving mode. When in power-saving mode, smartphones are not actively sending or receiving messages, but they still have their ears on the alert (“idle listening”) for incoming data and clear communication channels.

According to Shin and Zhang, “idle listening” occurs about 60 to 80 percent of the time that a phone is in power-saving mode. They also found that smartphones in idle listening mode consume roughly the same amount of power as when the smartphones are fully awake.

Their solution, E-MiLi, can help the smartphone save energy when it is in idle listening mode. E-MiLi works by slowing down the Wi-Fi card’s clock speed to about 1/16 of its normal frequency when the phone is in idle listening–which is analogous to having a person half-asleep. When the phone detects incoming information, it awakens and goes back to full speed.

The Shin-Zhang tandem found a way to enable the phone to recognize an incoming message even while the phone is in a semi-conscious, half-asleep state. They did it by using a new message header that the phone can detect even while in a slower mode. The message header, analogous to a recipient’s address, can be recognized by the half-asleep, idle-listening smartphone–just as you can “recognize that someone is calling your name even if you’re 90 percent asleep,” said Shin.

However, new firmware for gadgets is required so that the devices can “hear” the E-MiLi message headers. Shin and Zhang have succeeded in creating a prototype, although it is not yet commercially available. Hardware and device manufacturers will also need to adopt the firmware modifications so that their products can take advantage of E-MiLi.

If you want to read more about this new invention, you can check out Shin and Zhang’s paper entitled “E-MiLi: Energy-Minimizing Idle Listening in Wireless Networks” (PDF).

If you could choose which Android device to slap this new invention on, what Android device would it be?

Image credit: Rachel Calamusa (Flickr)

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