Remember superheroes scanning buildings using x-ray vision. Those comic heroes could see through walls, boxes and even clothes. Among them, superman’s’ x-ray eyes were exceptional. Thanks to MIT’s Wi-Vi technology, at least seeing through walls is soon to be a reality. In the not too distant future, you will witness devices and smartphones capable of seeing through the walls.
Will you believe if I tell you superman’s x-ray eyes were also a topic of interest to a bunch of research people? There are a handful of publications on the same. Of these, J.B. Pittenger’s publication entitled ‘On the plausibility of superman’s x-ray vision’ in 1983 is quite famous. He have discussed two possible theoretical solutions in his paper. If you are interested to know more on similar works, you can check out the publications listed right below.
- Pittenger, John B. “On the plausibility of Superman’s x-ray vision.” Perception12, no. 5 (1983): 635-639.
- Wininger, Kevin L. “A Look at Superman’s X-ray Vision.” Radiologic technology84, no. 5 (2013): 530-535.
- Livingston, Mark A., Arindam Dey, Christian Sandor, and Bruce H. Thomas. “Pursuit of “X-ray vision” for augmented reality.” In Human Factors in Augmented Reality Environments, pp. 67-107. Springer New York, 2013.
Imagine Tom using Wi-Vi technology to see Jerry behind the wall :D. Seems really cool, right?
Let’s swing back to the topic of concern, which is Wi-Vi. It’s always good to know about people behind such amazing technologies. Before knowing about the details about Wi-Vi, lets exactly do that.
People Behind Wi-Vi
Dina Katabi is a Professor in the Department of Electrical Engineering and Computer Science at MIT and co-director of the MIT Center for Wireless Networks and Mobile Computing. Most of her works revolve around wireless networks and she explores the new possible uses of wireless networks. She is also a recipient of “MacArthur fellow” award. Her work on Sparse FFT was chosen by the Technology Review as one of the 10 emerging technologies in 2012.
More at http://people.csail.mit.edu/dina/
Fadel Audib is a Ph.D. scholar in the Department of Electrical Engineering and Computer Science at MIT and his research supervisor is Dina Katabi. His most works are on tracking of objects and humans using radio signals.
More at http://people.csail.mit.edu/fadel/
//Above two pictures are properties of MIT
How does Wi-Vi works?
I will try not to dive into the superficial details so that this post serves the purpose as a good read for both enthusiasts and geeks. Being a researcher myself, I am partly sure I won’t be able to show full justice to that policy and hence people who don’t like details are welcomed to click SKIP .
Wi-Vi makes uses of Body Radio reflections of low power Wi-Fi signals. Thanks to the penetration ability of Wi-Fi signals, one could study about the reflections bouncing from human bodies behind the wall. Devices capture these reflections and using them they could be decode the motions of objects behind the wall. But as mentioned in the paper by MIT researchers, the power of Wi-Fi signals get reduced by an order of 3 to 5 times. Another challenge is to filter out the reflections from wall itself. So altogether all these makes the realization of Wi-Vi difficult. (An info for real enthusiasts: The reflections from walls will naturally overshadow the signals from bodies behind the walls like a camera flash on mirror prevents from capturing actual objects and hence, this effect is known as “Flash Effect”.)
Like its counterparts, Wi-Vi too overcomes these challenges by using MIMO (Multiple Input Multiple Output) radios. But unlike other systems, it uses a small antenna array (2 Tx + 1 Rx) and uses MIMO nulling technique to filter out reflections from static objects including walls. The motion is actually captured by spatial correlation techniques. It also discuss on tracking motions without using antenna array at reception side by making use of a radar technology known as ISAR (Inverse Synthetic Aperture Radar) method. It helps them to emulate a large antenna array setup.
You can understand the experimental setup by watching the working demo. For more details, you are encouraged to read the paper mentioned at the bottom of this post.
The features of Wi-Vi are listed below.
- Track motions of moving objects and humans
- Determine the number of human or any other moving objects (like robots with navigational facilities)
- Recognize simple gestures shown behind a wall
- Application scenarios could be intrusion detection, robot navigation, communication via gestures written in air
Wi-Vi really seems to be a promising technology. I really believe that if the technology is really developed to it’s true potential, it can realize most of the hi-fi technologies shown in Sci-Fi movies. People who happen to take this as research topic could try collaborating two or more Wi-Fi devices to recognize the gestures. May be think on developing a Wi-Fi router which have advanced capabilities. As a start, consider converting a Raspberry Pi (a single-board computer) to a router . It will surely add to the precision in the recognition process of gestures and other actions done in air 😀 .
- Adib, Fadel, and Dina Katabi. “See through walls with WiFi!.” In Proceedings of the ACM SIGCOMM 2013 conference on SIGCOMM, pp. 75-86. ACM, 2013.
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