How a Quick Wi-Fi Tweak Could Double Your Phone’s Battery Life

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The lowly battery: It’s one of the most important parts of any modern-day gadget, yet it’s been one of the slowest pieces of the technology puzzle to evolve. That smartphone in your pocket is exponentially more powerful than the first computer you ever used, yet you still have to plug it in every night.

We’ve had access to lithium-ion battery technology for more than 20 years now, and while batteries have gotten more efficient over time, it’s been advancements in power management tricks and ever-smaller components used by modern gadgets that have picked up most of the slack.

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When Apple announced the iPhone 4, for instance, the company touted its new “A4” processor as more nimble and efficient, but Apple also pointed out that the A4’s custom design meant that the chip could be shrunken down and, in turn, a larger, higher-capacity battery could be installed in the phone.

And when Samsung launched its 7-inch tablet, the Galaxy Tab, a teardown of the device revealed that its battery took up most of the internal space.

While shrinking internal components can lead to longer battery life thanks to the simple addition of bigger batteries, advancements in power management techniques can help increase battery life as well. You may have noticed that even relatively inexpensive laptops can clear eight hours with ease thanks to more efficient processors; some business laptops can even clear a whopping 30 hours when using extended battery configurations.

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Often at the heart of what causes a device’s battery to drain is the fact that even when it’s not in use, it’s still connected to some sort of network. Your phone may be in standby mode, but it’ll still ring if someone calls you and it’ll still ding if someone sends you an e-mail. That constant awareness plays a large part in draining your battery.

However, a team from the University of Michigan has developed a new method for keeping wirelessly-enabled devices constantly connected while in a very low-power state—so much so that it “could extend battery life by as much as 54 percent for users on the busiest networks.”

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The technique is being likened to a “subconscious mode” for smartphones and other connected devices, and entails ratcheting the power consumed by an idling device’s Wi-Fi chip down to a fraction of its normal level while still allowing it to receive incoming messages.

University of Michigan computer science and engineering professor Kang 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.” The team calls the concept “E-MiLi,” or Energy-Minimizing Idle Listening.

According to the University of Michigan’s article:

“Here’s how E-MiLi works: It slows down the WiFi card’s clock 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 challenge, however, “was getting the phone to recognize an incoming message while it was in this slower mode.”

University of Michigan computer science and engineering professor Kang 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.” The team calls the concept “E-MiLi,” or Energy-Minimizing Idle Listening.

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The team says “that E-MiLi is capable of reducing energy consumption by around 44 percent for 92 percent of mobile devices in real-world wireless networks.” Immediately-noticeable power savings for most devices that are currently available on the market? Sounds great. What’s the catch?

According to the team:

“In addition to new processor-slowing software on smartphones, E-MiLi requires new firmware for phones and computers that would be sending messages. 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.”

So you’d have to get the software installed on handsets and you’d have to get companies running the e-mail servers to install the software on their end. That could take some time and convincing, but perhaps the biggest selling point is that it wouldn’t require new hardware. And down the line, as the team points out, new products could ship with the modifications already in place.

The team will be presenting this research at a mobile device conference in Las Vegas tomorrow, and the University of Michigan is already “pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.”

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