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'Subconscious mode' could boost smartphone run times by over 50 percent


September 18, 2011

A new system that puts smartphones into 'subconscious mode' could boost battery run times by over 50 percent (Photo: gailjadehamilton via Flickr)

A new system that puts smartphones into 'subconscious mode' could boost battery run times by over 50 percent (Photo: gailjadehamilton via Flickr)

University of Michigan researchers have proposed a new power management system for smartphones that could dramatically improve battery life. Working with doctoral student Xinyu Zhang, computer science and engineering professor Kang Shin has created a proof-of-concept system known as E-MiLi, or Energy-Minimizing Idle Listening, that addresses the energy waste that occurs when "sleeping" phones are looking for incoming messages and clear communication channels. For users on the busiest networks, it could extend battery life by up to 54 percent.

E-MiLi slows down the clock of a phone's WiFi card by up to 1/16 its normal frequency in order to save power, but then kicks it back up to full speed when information is coming in. The phone uses the header of the incoming message to wake itself up from its "subconscious mode," so the clock is at full speed to receive the main message.

Not only would the system require processor-slowing software to be loaded onto smartphones receiving calls, but it would also require firmware to be installed on phones and other devices that would be sending them. This is because the header would need to be encoded in such a way that the receiving phone could detect it. Shin and Zhang have created such firmware, but WiFi chipset manufacturers would have to adopt it, and then smartphone manufacturers would in turn have to start using those chips. If that were to all come together, older phones without E-MiLi would reportedly still be able to receive calls made by newer phones running the firmware.

While 54 percent was the high mark, the U Michigan system was found to reduce energy consumption by approximately 44 percent in 92 percent of mobile devices when tested using real-world wireless networks.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Doesn\'t Android\'s Juice Defender already do something similar? I use the app, and it boosts my battery life (on average) in excess of 55%. So is this (E-MiLi) really something new? Or an adaptation of something that already exists?

Timmy Toady

I can\'t actually believe that the smartphone manufacturers hadn\'t already come up with this idea, it\'s so obvious. I have worked on low power products before and reducing clocking speed is one of the first things you do! Do companies invest anything in their own R&D anymore or are the bean counters taking over the whole world?



There has to be more to this than just modifying the different operation modes of the mcu on the phone..modern day mobile chipsets already have extremely low power runtime modes. We\'ve begun testing with new chipsets that operate at only .9V to wake and consume barely any power in sleep. The real issue is what level the phone has to operate at in order to stay in contact with the cell tower. We\'ve begun using cell phones in our business to hargest energy from the ambient radio energy that the phone gives off. Its not much but it will recharge small electronics.

Rocky Stefano

WIFI??? That\'s not the main battery killer!

Most phones do not have that running most of the time anyway - my current favorite, XV6900 (AKA HTC Touch/Vogue) does not even have wifi. Hoping that meant cellular radio since that is what runs down most phone batteries (although Slashdot discussion indicates this technique has been applied, several times, to cellular technology over the last 2+ decades or so).


I\'m with Timmy, Juice Defender on Android works like a charm! The beta is free to use too.


@Rocky any idea what percentage battery life the RF uses? I previously presumed the RF was very efficient and that the LCD sucked the battery juice?


how about a nice graph showing what percentage each component of a phones uses?

Jamie Palmer
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