US researchers have developed a system called HUSH to reduce battery drain from smartphone apps which frequently wake up and run in the background.
HUSH identifies background activities that are not important to the user experience on a per-app basis and suppresses unnecessary activity when the screen is off.
The key insight is that not all background activities are equally important to users. For example, frequent Facebook updates during screen-off mode may be useful to a user who checks Facebook feeds and reacts to notifications often, but much less so for a user who rarely checks such updates.
The tool follows a study by researchers at Purdue University, Intel and Mobile Enerlytics, which looked at the use of 2,000 Samsung Galaxy S3 and S4 phones served by 191 operators in 61 countries.
Y Charlie Hu, a Purdue professor of electrical and computer engineering, explained that “apps wake the phone up periodically during screen-off to do useful things, but then afterward, they should let the phone go back to sleep.”
However, this does not happen “because of software bugs and, specifically, due to the incorrect use of Android power control application programming interfaces called wakelocks”.
“We presented the first study a few years back showing wakelock bugs could cause significant energy drain. But this is the first study showing that wakelock bugs appear prevalent on real users’ phone,” he added.
In screen-off mode, a smartphone also continues draining power for various legitimate maintenance purposes, such as to connect to Wi-Fi beacons or mobile networks. In efforts to extend battery life, the researchers will work to reduce energy drain from these legitimate functions.
The research is ongoing, with implications to the 5G wireless network design, according to a statement by Purdue University.
“The big picture is that we want to double the battery life for smartphones,” Hu said. “This is going to be a non-trivial journey because much of the battery drain is caused by various apps when the screen is on and also legitimate maintenance functions.”