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“Microsleep” Software Doubles Battery Life of Connected Gadgets

The views expressed are those of the author and are not necessarily those of Scientific American.

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smart phone,network,batteryNo matter how fancy mobile gadgets get, they’re useless when their batteries run out. With the push toward cloud computing and the always-on wireless culture gaining momentum every day, laptop, tablet and smart phone batteries are being asked to do more despite no real breakthroughs in battery technology hitting the market.

Consider: Twitter users send 200 million tweets daily, up from 65 million just a year ago. Meanwhile, Google is banking on the success of several new mobile apps to help its Google+ social network effort dethrone Facebook.

All of these services are draining enough to make any mobile device want to take a nap, which isn’t such a bad idea, according to one Duke University researcher. Justin Manweiler, a computer science graduate student at Duke’s Pratt School of Engineering, has developed software he calls SleepWell, which is designed to double the battery life of Internet-connected devices increasingly called on to upload and download music, images and video via WiFi.

Mobile devices today waste a lot of energy searching for a WiFi signal and then staying connected while overtaxed wireless networks ferry data to and from them. SleepWell allows a mobile device to slip into power-saving mode while it is waiting its turn to connect. This is no small matter, particularly when scores of caffeine-craving technophiles gather at the local Starbucks to take advantage of the free wireless access. Manweiler likens the competition for WiFi to big-city traffic. When workers leave their offices en masse at the end of the day, they clog up the roads and rail lines. If these workers staggered the times they left, the transit systems would be less crowded, and it would take less time to get home. Similarly, if mobile devices took their turn accessing WiFi access points, data would move faster and these devices would use less energy.

SleepWell is installed on the devices that create a WiFi network infrastructure, including WiFi routers and access points. As such, it is designed so that any mobile device—whether it uses Apple OS X, Google Android, Windows or some other platform—can take advantage of it.

The SleepWell software differs from the "sleep" mode already available in many devices. An operating system’s version of sleep is designed to work over long time scales—minutes, hours or days. "SleepWell is enabling short ‘sleep’ periods multiple times per second," says Manweiler, who works under the direction of Romit Roy Choudhury, a Pratt School assistant professor of electrical and computer engineering. "These sleep periods are so short, the user remains unaware and unaffected."

During testing, Manweiler found that SleepWell could double the battery life of mobile phones. "We ran lots of live experiments using real off-the-shelf smart phones, mostly Google Android phones," he says. "We tested with a variety of use cases, including the user watching a movie trailer on YouTube, playing music on Pandora and Last.FM Internet radio, and downloading a large file from the Web."

The extent to which battery life would be prolonged of course varies depending on the situation. Still, Manweiler hopes the brief naps that SleepWell affords mobile devices will add up to significant energy conservation when WiFi networks are in high demand.

Image courtesy of Martin McCarthy, via

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  1. 1. CarlTres 1:38 pm 07/1/2011

    So the question is, when will this be available for actual use?

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  2. 2. osmposm 5:26 pm 07/1/2011

    I can only wish never, Carl – about the only limiting factor on continuous mobile use currently is battery life, and if it gets doubled we’ll end up with anyone under 40 spending an even lower proportion of their waking life bothering to have full-on personal conversations with other people.

    Talking to infant children, for example, will become a thing of the past: even now I watch in despair as all too many are wheeled down the road in their buggies, ignored while their mothers chat to their far less demanding friends. And with everyone now leaving their cellphones on permanently, sustained conversations with friends over dinner will become even rarer.

    About the only peace and quiet we oldies get now is when we hear those blessed words "Sorry, gotta go – my battery’s about to die…"; when did you last hear someone say "Sorry, gotta go – there are other people next to me on the train, and I think they need some relief from my loud and incessant gabbling", or "Can’t talk, I need to explain to my three-year old why bare brown trees turn green in the spring"?

    Yes, I know I’m a dinosaur, but I’ll go extinct fighting!

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  3. 3. Xoxcatpl 11:28 pm 07/1/2011

    I wonder whatever happened to the fuel cell batteries that got so much publicity a few years ago. The claim was that one of these devices would give a laptop ten or twelve hours continual use. And instead of having to recharge it, you would just refill the methanol supply, like a refillable lighter. I guess this was another one of the oh-so-promising technologies that never arrived.

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  4. 4. StarvinMarvin 7:25 pm 07/7/2011

    If you are interested in getting something that helps your lifestyle then I have been using something called Sweet Dreams.

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