Wireless localizer means password-free WiFi, safer drones, and smarter homes

Tired of looking for WiFi? It's about to look for you.
Written by Greg Nichols, Contributing Writer

Tired of crossing your fingers while trying to locate a WiFi signal? What if, instead, the WiFi could locate us?

The smart cats at MIT are on it.

In a new paper, a research team led by professor Dina Katabi of MIT's Computer Science and Artificial Intelligence Lab (CSAIL) presents a system that enables a single WiFi access point to locate users to within tens of centimeters, without any external sensors. The group demonstrated the system in an apartment and a cafe, while also showing off a drone that maintains a safe distance from its user with a margin of error of about four centimeters.

According to researchers the technology could mean safer drones, smarter homes and password-free WiFi.

Experiments conducted in a two-bedroom apartment with four occupants show that the system can correctly identify which room a resident is in 94 percent of the time -- showing that it could have immediate use in smart-homes. For the cafe demo, the system was 97 percent accurate in distinguishing in-store customers from out-of-store intruders -- meaning it could be used by small businesses to prevent non-customers from stealing their WiFi. (32 percent of Americans have copped to this cyber-crime.)

The system locates users by calculating the "time-of-flight" that it takes for data to travel from the user to an access point. It's 20 times more accurate than existing systems, computing time-of-flight with an average error of 0.47 nanoseconds.

What's different is how that info is measured. Existing localization methods have required four or five WiFi access points. That's because today's WiFi devices don't have wide enough bandwidth to measure time-of-flight, so researchers have only been able to determine someone's position by triangulating multiple angles relative to the person.

What the new system adds is the ability to calculate not just the angle, but the actual distance from a user to an access point, as determined by multiplying the time-of-flight by the speed of light. Knowing both the distance and the angle allows you to compute the user's position using just one access point. This is encouraging news for the many small businesses and consumers that don't have the luxury of owning several access points.

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