McCormick School of Engineering, Northwestern University

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Group Optimizes Computers Based on User Satisfaction, Looks for Android Phone Users

May 13, 2009
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If you have a laptop, you’ve been there: While the manufacturer promised hours of available battery time, you find that after you’ve been working on the laptop for a short time, the screen goes black. Battery dead.

Improving battery life is the pursuit of many scientists around the world, but computer scientists at the McCormick School of Engineering and Applied Science at Northwestern University are taking a different approach: looking at how to save power by incorporating individual user perception, performance expectations, and usage behavior when controlling clients, servers, and networks.

The research, called the Empathic Systems Project and headed by electrical engineering and computer science professors Peter Dinda, Gokhan Memik, and Robert Dick, ultimately explores how to incorporate end-user satisfaction and guidance into computer systems and computer architecture design and implementation.

When it comes to computer power, the idea is that computer scientists can scale back the amount of power the system uses when additional power does not make a difference in user satisfaction.

“Typically, computer designers will just measure computer performance and won’t take users into account when they are designing the computer,” says Alex Shye, a graduate student involved in the project. “We try to take the individual user into account while optimizing the computer’s performance, as well.”

In addition to Shye, electrical engineering graduate students Yan Pan, Benjamin Scholbrock, and J. Scott Miller have studied user satisfaction using biometrics: measuring factors like pupil movement and how hard a user types on the keyboard to determine satisfaction, then changing the processor frequency to save power and seeing if that affected user satisfaction.

“We saw there were instances where scaling back the central processing unit frequency didn’t affect the user satisfaction, but it saved power,” Shye says. Some studies done by the group show that it is possible to save as much as 50 percent of total system power on a laptop by doing this.

But now the group wants to take their studies to another realm: cell phones and PDAs, and they’re looking for volunteers to help them.

“Cell phones, PDAs, and iPods are becoming more and more popular,” Shye says, “And they are even more power-constrained. We’re trying to see if we can understand how the system uses power based on what the user does.”

The group is looking for volunteers with Google Android phones to download their application, which logs activity relevant to understanding system performance and power consumption. By the time the data gets to the group’s server, it is anonymous, and users have the ability to turn off the logger at any time.

“By installing our logger, volunteers will help us collect real information about user activity and usage patterns on real devices; we can use this information to get a power breakdown of each of the components — the processor, wifi radio, the cell radio,” Shye says. “And that’s what is important. Once we understand the power consumption with respect to real usage patterns, we can develop new optimizations to save power while maintaining a high user satisfaction.”

For more information on the Empathic Systems Project, click here.
To participate in the Google Android project, install the NU Jamlogger For more information, click here.

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