If your smartphone was allowed to be just barely awake, it could extend battery life by as much as 54 percent. That's the claim of a research team at the University of Michigan that has invented a new "subconscious mode" for smartphones and other WiFi enabled mobile devices.
Computer science and engineering professor Kang Shin and doctoral student Xinyu Zhang found that, even when devices are in a power-saving mode and not actively sending or receiving data, they're still actively listening for incoming information and spending energy looking for a clear channel of communication on busy networks. Phones in power-saving modes were found to be performing these functions up to 80 percent of the time.
"This idle listening often consumes as much power as actively sending and receiving messages all day," says Shin.
How It Works
Shin and his team developed a way for smartphones to listen more efficiently, called Energy-Minimizing Idle Listening, or E-MiLi. Basically, a piece of software would be added to smartphones to slow down the clock on the WiFi card to 1/16th its normal speed. Shin says the challenge was how to allow the phone to recognize an incoming message while it was slowed down to a crawl.
"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."
There's a catch though. All headers would need to be encoded in this new and detectable way, and that has to occur on the sending end. Shin and his team have created new firmware to do the encoding, but it needs to be in all mobile devices on a network for E-MiLi's use to become widespread and have the maximum battery-saving impact. That means device manufacturers need to adopt the firmware modifications and incorporate new chips in their products. That's not quite as easy as downloading a new app.
Shin points out that E-MiLi would be backwards compatible, so phones without the new firmware and software would still be able to receive E-MiLi encoded messages in the future, if its use ever becomes widespread.
Shin and Zhang will be making their pitch to the industry when they present their concept next week at the ACM International Conference on Mobile Computing and Networking in Las Vegas.