Indoor GPS Makes Strides

Efforts to develop an indoor version of GPS use smart phones and existing wi-fi. Larry Greenemeier reports

Join Our Community of Science Lovers!


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


GPS is utterly useless for finding your wife or kids (or even locating yourself) at the mall. What we need is an indoor equivalent of GPS. And researchers have been working on it.

Most recently a team of Stanford students launched a project called WiFiSLAM. Their goal is to develop mobile applications that let your smart phone pinpoint its location in real-time to within 2.5 meters. It would do it by sensing ambient WiFi signals already present in buildings. The phone's internal compass and accelerometer also come into play to help determine its location.

The students also want to create apps that could be use for marketing, depending upon what store a smart phone user is standing near. Another app might connect the user's location to social networks.

Other indoor positioning systems try to find a user's position using radio, ultrasound or infrared signals. But these approaches require special radio-frequency tags. WiFiSLAM's approach is promising because it uses existing wireless networks and the smart phone already in your pocket.

—Larry Greenemeier

[The above text is a transcript of this podcast.]

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American

Subscribe