'Subconscious mode' could boost smartphone run times by over 50 percent
By Ben Coxworth
September 18, 2011
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.