Technical Reports

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Technical reports by members of the SPAN lab.

SPAN gets press for networks that "See Through Walls"

A new SPAN technical report on Variance-based Radio Tomography posted on Wednesday September 30 to was reported on by a variety of local, national, and international media. The report was first picked up by the MIT Technology Review Physics Blog, with later stories from The Economist, Slashdot and Gizmodo. Other articles on the technical report appeared in Ars Technica,, Discover, and On Sunday, October 4, a report by KSL TV in Salt Lake City appeared during the local news broadcast.

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Technical Report Posted: Through-Wall Tracking Using Variance-Based Radio Tomography Networks

variance-based radio tomographic imagingJoey Wilson and Neal Patwari have posted a new technical report. The abstract reads:

This paper presents a new method for imaging, localizing, and tracking motion behind walls in real-time. The method takes advantage of the motion-induced variance of received signal strength measurements made in a wireless peer-to-peer network. Using a multipath channel model, we show that the signal strength on a wireless link is largely dependent on the power contained in multipath components that travel through space containing moving objects. A statistical model relating variance to spatial locations of movement is presented and used as a framework for the estimation of a motion image. From the motion image, the Kalman filter is applied to recursively track the coordinates of a moving target. Experimental results for a 34-node through-wall imaging and tracking system over a 780 square foot area are presented.

J. Wilson and N. Patwari, "Through-Wall Motion Tracking Using Variance-Based Radio Tomography Networks",, Oct, 2009.

Tech Report: Radio Tomographic Imaging With Wireless Networks

Joey Wilson and Neal Patwari of the SPAN lab have published a technical report entitled "Radio Tomographic Imaging With Wireless Networks." RTI is a technology that is capable of imaging and tracking objects within a wireless network. This report discusses the linear formulation and reconstruction algorithms that can be implemented using only received signal strength, and describes some results that we've obtained with a prototype implementation. This is still a work in progress, so please report any corrections that you find.

Radio Tomographic Imaging with Wireless Networks
Joey Wilson and Neal Patwari, , University of Utah, 17 Sep 2008

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