Mobile Industry: Battery Life Technique Described

Apple iPhone 4 
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In the mobile industry, a new "subconscious mode" for smartphones and other WiFi-enabled mobile devices could extend battery life by as much as 54 percent, U.S. researchers say.

University of Michigan computer scientists say even when mobile devices are in power-saving modes and not actively sending or receiving messages, they're still on alert for incoming information and searching for a clear communication channel, which uses up battery power.

This energy-taxing "idle listening" is occurring during a large portion of the time phones spend in power-saving mode and uses roughly the same amount of power as when they're fully awake, they say.

UM computer science and engineering Professor Kang Shin and doctoral student Xinyu Zhang say their new power-management approach can make smartphones perform this idle listening more efficiently, reported.

Their Energy-Minimizing Idle Listening strategy slows the WiFi hardware's clock by up to 1/16 of its normal frequency but jolts it back to full speed when the phone notices information coming in.

The challenge, 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."

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