Sensing and Processing Across Networks at Utah

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 (Accepted)

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.

SPAN lab's journal article titled, Correlated Link Shadow Fading in Multi-hop Wireless Networks , authored by Piyush Agrawal and Neal Patwari appeared in the August 2009 issue of Transactions on Wireless Communication.

The research of SPAN researchers Jessica Croft and Joey Wilson is featured in the Summer 2009 ECE Communicator newsletter. The ECE Communicator is the newsletter of the University of Utah Department of Electrical and Computer Engineering and is read by department students, alumni, friends, employers, and others. Jessica Croft's research in using the radio channel to generate shared secrets between two radios for purposes of improved privacy is featured on page 4 of the newsletter. Joey Wilson's research in radio tomographic imaging (RTI), and his award at the ACM MobiCom 2008 conference as the Student Research Competition winner, is featured on page 5. Congratulations to these students for having their research selected as two highlights of the research being conducted in the ECE Department as a whole!

Prof. Neal Patwari will be the publicity chairperson for the 9th ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN) 2010. Naturally, he wants you to be there! The IPSN conference will take place from April 12 - 16, 2010 in Stockholm, Sweden. As in the previous two years, the conference will be part of Cyber-Physical Systems Week (CPS Week), which brings together five leading conferences - RTAS, IPSN, HSCC, CPSC and LCTES - as well as several workshops and tutorials on various aspects on the research and development of cyber-physical systems. The paper submission deadlines for IPSN 2010 are as follows:

• Abstract deadline: Friday, October 23rd, 2009
• Full papers due: Friday, October 30th, 2009

The journal paper, Correlated Link Shadow Fading for Multi-hop Wireless Networks, by Piyush Agrawal and Neal Patwari, which will appear in the IEEE Transactions on Wireless Communications is now posted as pdf for download.