Researchers see through walls with Wi-Fi

<div dir="ltr" style="text-align: left;" trbidi="on"><div style="background-color: white; font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 22px; margin-bottom: 20px; outline: none; text-align: justify;">MIT researchers have <a href="http://people.csail.mit.edu/fadel/wivi/" style="color: #05408f; outline: none; text-decoration: none;" target="_blank">demonstrated</a> the application of using Wi-Fi signals to track the movements, locations and number of people inside buildings. Dubbed Wi-Vi, the inexpensive and portable "through-the-wall" radar system could have practical applications in law enforcement, search and rescue operations and home security, even if it does present some potential privacy concerns.</div><div style="background-color: white; font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 22px; margin-bottom: 20px; outline: none; text-align: justify;">While listening in on radio signals transmitted by standard Wi-Fi routers and access points, a Wi-Vi transceiver<a class="vglnk" href="http://www.bizrate.com/blankets/index__af_assettype_id--4__af_creative_id--3__af_id--[AFF-ID]__af_placement_id--[AFF-PLACEMENT-ID].html" rel="nofollow" style="color: #05408f; outline: none; text-decoration: none;" target="_blank" title="Link added by VigLink">blankets</a> the area with its own low-power, directional, wireless transmissions. As objects move within the target area, signals are absorbed and reflected differently. The device monitors these slight changes, giving Wi-Vi operators the ability to determine the movements, locations, speeds and the number of moving objects (e.g. people) behind walls.</div><div class="video-container" style="background-color: white; font-family: Arial, Helvetica, sans-serif; font-size: 14px; height: 0px; line-height: 22px; margin-bottom: 10px; outline: none; overflow: hidden; padding-bottom: 401.625px; position: relative;"><iframe allowfullscreen="" frameborder="0" height="480" src="http://www.youtube.com/embed/uJkQzLjYBFI" style="height: 401.625px; left: 0px; margin-bottom: 12px; outline: none; position: absolute; text-align: justify; top: 0px; width: 714px;" width="640"></iframe></div><div style="background-color: white; font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 22px; margin-bottom: 20px; outline: none; text-align: justify;">Since Wi-Vi relies on physical radio waves instead of higher network layers, operators do not need access to a Wi-Fi network (i.e. no password is needed) in order to make use of signals emanating from a nearby Wi-Fi router or AP.</div><blockquote style="background-color: white; border-left-color: rgb(238, 238, 238); border-left-style: solid; border-left-width: 5px; font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 22px; margin: 10px 20px; outline: none; padding: 15px;"><div style="margin-bottom: 20px; outline: none; text-align: justify;">Wi-Vi can detect objects and humans moving behind opaque structural obstructions. This applies to 8" concrete walls, 6" hollow walls, and 1.75" solid wooden doors. A Wi-Vi device pointed at a closed room with 6" hollow walls supported by steel frames can distinguish between 0, 1, 2, and 3 moving humans in the room. Computed over 80 trials with 8 human subjects, Wi-Vi achieves an accuracy of 100%, 100%, 85%, and 90% respectively in each of these cases.</div><div style="outline: none; text-align: justify;">Source: <a href="http://people.csail.mit.edu/fadel/papers/wivi-paper.pdf" style="color: #05408f; outline: none; text-decoration: none;" target="_blank">people.csail.mit.edu</a> (pdf), <em style="outline: none;">See Through Walls with Wi-Fi!</em></div></blockquote><div style="background-color: white; font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 22px; margin-bottom: 20px; outline: none; text-align: justify;">While Wi-Vi doesn't provide anything that resembles an actual <em style="outline: none;">photograph </em>of what's behind a wall, the results are detailed enough to be used for detecting body gestures (e.g. hand waves) with a remarkable amount of accuracy.</div><blockquote style="background-color: white; border-left-color: rgb(238, 238, 238); border-left-style: solid; border-left-width: 5px; font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 22px; margin: 10px 20px; outline: none; padding: 15px;"><div style="outline: none; text-align: justify;">In the same room, and given a single person sending gesture based messages, Wi-Vi correctly decodes all messages performed at distances equal to or smaller than 5 meters. The decoding accuracy decreases to 75% at distances of 8 meters, and the device stops detecting gestures beyond 9 meters. For 8 volunteers who participated in the experiment, on average, it took a person 8.8 seconds to send a message of 4 gestures.</div></blockquote><div style="background-color: white; font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 22px; margin-bottom: 20px; outline: none; text-align: justify;">Unfortunately for potential voyeurs (and fortunately for privacy advocates), it remains a far cry from detailed airport scanners, X-ray vision or even Batman's implausible <a href="http://www.comicbookmovie.com/fansites/nailbiter111/news/?a=77546" style="color: #05408f; outline: none; text-decoration: none;" target="_blank">cell phone "sonar"</a> network, but it could prove to be an inexpensive way to gain life-saving insight for rescue operations and police busts. As with many technologies though, it's not difficult to imagine Wi-Vi being subverted by tech-savvy criminals, like burglars or kidnappers, to get the drop on unsuspecting victims.</div><div style="background-color: white; font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 22px; margin-bottom: 20px; outline: none; text-align: justify;"><a href="http://www.techspot.com/news/53073-researchers-see-through-walls-with-wi-fi.html" target="_blank">Read More...</a></div></div>

Researchers see through walls with Wi-Fi

MIT researchers have  demonstrated  the application of using Wi-Fi signals to track the movements, locations and number of people inside bui...

Read more »