Sensing and Processing Across Networks at Utah

The SPAN lab has published a public data set for radio tomographic imaging. This data is free to use for academic purposes. In publications using this data set, you must cite:

• Joey Wilson and Neal Patwari, Radio Tomographic Imaging with Wireless Networks,
  IEEE Transactions on Mobile Computing, (accepted), appeared online 8 Jan, 2010.

Commercial use of this data is strictly prohibited without written consent from the SPAN lab.

If you use this data set, we'd appreciate hearing how you used it. Please contact Joey Wilson and Neal Patwari.

The IEEE Signal Processing Society has announced that the article, "Locating the Nodes: Cooperative Localization in Wireless Sensor Networks", authored by Neal Patwari, Joshua N. Ash, Spyros Kyperountas, Alfred O. Hero III, Randolph L. Moses, and Neiyer S. Correal, has been awarded the 2009 Signal Processing Magazine Best Paper Award.

For those of you who are interested in RTI, Joey Wilson will be presenting at the Applied Mathematics Seminar at the University of Utah. Here's the details:

Speaker: Joey Wilson, SPAN PhD Candidate and Founder of Xandem Technology
When: January 25, 2009, 4:15PM-5:15PM (see http://www.math.utah.edu/applied-math/)
Title: Radio Tomographic Imaging: Using Simple Wireless Networks to See Through Walls and Locate People

Abstract: Radio Tomographic Imaging (RTI) is an emerging technology that is capable of detecting and locating humans behind walls and through obstructions. This presentation will discuss how RTI works, specifically detailing the inverse mathematical models and solutions. Current research and ideas for future mathematical research will be discussed.

The SPAN lab team hosted a class of 4th graders from Jackson Elementary School on Friday, Dec. 11. The 4th graders learned generally what electrical engineers do, and specifically, the mathematics and engineering of tomography. Tomography can be explained as finding numbers to solve addition problems, and the class worked on finding images given their row and column sums. Then, they conducted experiments using the radio tomographic imaging testbed. We thank the Adelante program and the students who visited for spending their time with us. Our tomography activity plan, slides, and worksheets are posted, along with photos from the event.

The video of SPAN researcher Joey Wilson conducting a variance-based radio tomographic imaging (VRTI) and tracking experiment has surpassed 100,000 views. As of Monday, Nov. 16, 2009, the video had 100,729 views, according to YouTube.com's statistics. The first large wave of views came after Wired.com's Kim Zetter published a story on the technology and linked to the video. International press also led to many views of the video, including Der Spiegel, The Economist, and the Finnish Science magazine Tiede.

The University of Utah is holding College of Engineering Day on October 31st in the Warnock Engineering Building (map), and the SPAN lab will perform a live demonstration of our radio tomographic imaging system. Yes, it's Halloween, but its no trick! We are actively recruiting the next generation of engineering students. COE Day is a half-day event, 9:00am - 12:30pm, open to high school students, undecided majors and transfer students interested in engineering. This event is designed to introduce students to a variety of engineering disciplines, and the SPAN demo is just one of many that you can see.

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

Video Courtesy of KSL.com

Joey 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", arXiv.org, Oct, 2009.

A paper by SPAN graduate student Joey Wilson, Andrew Nelson, and Behrouz Farhang has been accepted for publication in the IEEE Transactions on Circuits and Systems II. Joey performed most of the research for this paper while employed by L-3 Communications CSW in Salt Lake City, UT.

Modern implementations of discrete-time phase-locked loops (DT-PLLs) often contain delayed feedback. The delays are usually a side effect to pipelining, filtering, or other inner-loop mechanisms. Each delay increases the order of the system by introducing an additional pole to the closed-loop transfer function, and in many cases, makes the traditional type-2 loop equations obsolete. This paper describes how the second-order notions of damping and natural frequency can be applied to type-2 DT-PLLs in the presence of any number of delays. It provides equations for loop parameters that will provide a desired transient behavior based on damping and natural frequency, along with a test to ensure the accuracy of the results. The novelty of this work is that loop parameters can be found in closed-form and ensured to be accurate, without the need for human interaction, simulations, or numerical root-finding algorithms.

J Wilson, A. Nelson, B. Farhang, Parameter Derivation of Type-2 Discrete-Time Phase-Locked Loops Containing Feedback Delays, IEEE Transactions on Circuits and Systems II, Dec. 2009

The University of Utah's Lassonde center has selected the SPAN lab's radio tomographic imaging (RTI) technology for the 2009-2010 business development program. Each year, the Lassonde center chooses a few university-owned technologies that show promise of successful commercialization. Lassonde students studying business, law, and engineering form teams that research the commercial viability of the technologies, then prepare business plans.

Troy D'Ambrosio (director of the Lassonde program), Matt Dee, Deven Dustin, Vatsala Kaul, and Joey Wilson (from the SPAN lab) will make up the team. For more information about the Lassonde entrepreneur center, see their website at www.lassonde.utah.edu.