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OPLIN 4cast #484: Locating Wi-Fi users

Posted in 4cast

Wi-Fi signalIt’s possible that just about every library in Ohio has had people sitting outside the library using their Wi-Fi when the library is closed. That happens so often, in fact, that administrators of the E-rate program call this “ancillary” use and consider it normal. Most libraries don’t seem to mind, but in some cases, a library may have a branch in a mall or otherwise in close proximity to other businesses and want to limit Wi-Fi use to actual library users. For those cases, MIT research announced last week may promise a solution.

  • Wireless tech means safer drones, smarter homes and password-free WiFi (MIT News | Adam Conner-Simons)  “In a new paper, a research team led by Professor Dina Katabi present a system called Chronos that enables a single WiFi access point to locate users to within tens of centimeters, without any external sensors. The group demonstrated Chronos 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.”
  • MIT’s wireless localizer could mean password-free Wi-Fi (PC Magazine | Angela Moscaritolo)  “Existing localization methods determine someone’s position by ‘triangulating multiple angles relative to the person,’ a process that requires multiple Wi-Fi access points. Chronos, on the other hand, can calculate not just the angle, but the distance from a user [to] an access point. ‘Knowing both the distance and the angle allows you to compute the user’s position using just one access point,’ PhD student Deepak Vasisht, who helped author a paper about the new technology, said in a statement.”
  • New wireless tech from MIT promises password-free Wi-Fi (PC World | Katherine Noyes)  “Making it all possible was Vasisht’s observation that signals travel over the air from transmitter to receiver at a different frequency than they do within a Wi-Fi device during the process of being detected, said Dina Katabi, an MIT professor who led the research team, in an interview on Tuesday. After coming up with an algorithm to exploit that fact, the researchers tested the technology in a two-bedroom apartment with four occupants and found that Chronos can correctly identify which room a resident is in 94 percent of the time. In a cafe, it was 97 percent accurate in distinguishing in-store customers from out-of-store intruders, meaning that passwords could be eliminated.”
  • MIT turns Wi-Fi into indoor GPS (IEEE Spectrum | Mark Harris)  “There are some limitations, however. Although Chronos can run on existing Wi-Fi devices using just an app (or a firmware upgrade for an access point), each device has to undergo a one-time distance calibration. And because Chronos takes around one-tenth of a second to sweep all the Wi-Fi bands, its accuracy plunges if the devices are moving relative to one another during this initial setup.”

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