Finding Your Way


GPS is a fixture in so many connected devices these days, it can seem like it was always available. What would we do without GPS in our phones, PNDs (personal navigation devices), and personal trackers? But GPS has limitations. It can be difficult to always get a signal indoors. But tech firms and researchers are working on new ways to make location-based services more useful.

According to researchers from Duke University,, it’s been a challenge to attain GPS-level location quality indoors. At Duke, a team led by Romit Roy Choudhury has been working on indoor localization. Roy is associate professor of computer engineering at Duke’s Pratt School of Engineering and principal investigator for the Duke research team.

The team is creating a system that uses landmarks indoors to pinpoint location. The idea is similar to the way a person uses a specific landmark as a waypoint when directing someone.

“Our technique adopts the same intuition—it takes advantage of ‘invisible’ landmarks in indoor environments that a mobile phone can sense using its built-in sensors,” says Roy Choudhury. “Example landmarks could be distinct motion signatures created by elevators or stairwells, because the phone can detect motion, or certain dead spots where Wi-Fi or 3G signals are absent.”

The phone senses these landmarks and uses them to infer its current location. Once it has established a point, it can track its path using built-in motion sensors and compasses to continue to determine where it is. Researchers say over time, the location might become inaccurate, but additional landmarks allow the phone to correct its location.

The application is known as UnLoc, which is short for unsupervised indoor localization. The more the application is used, the better it becomes as it learns more about certain buildings or locations. Additionally, it can drain a phone’s battery less quickly than GPS.

There are a variety of proposed applications for the UnLoc technology. Researchers imagine it could someday be used to help people navigate in hospitals or smart homes, as well as shopping centers. Right now, the Duke team is testing the technology at Northgate shopping mall in Durham, N.C., as well as in the computer science and engineering buildings on Duke’s campus.

Perhaps one day all of our phones will include a version of UnLoc technology. Until then, we’ll just have to rely on GPS, and our own sense of direction.

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June/July 2014
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