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University of Hawaii

Electrical Engineering

Indoor navigation - using WiFi access points and time of flight of electromagnetic signals

Date: 2019-02-26           Add to Google Calendar
Time: 6:30pm - 8:00pm
Location: Holmes Hall 389
Speaker: Berthold K.P. Horn, Professor of Computer Science and Engineering and at CSAIL, MIT

Co-Sponsored by the IEEE Hawaii Microwave Theory & Techniques Society and Young Professional Affinity Group, and the University of Hawaii IEEE Student Branch

Abstract:  Being able to accurately locate one’s position indoors has several useful applications, such as guiding one to a lecture hall in an unfamiliar building --- particularly when it is not a building based on a simple rectangular design. GPS signals do not penetrate structures well and in any case do not provide the accuracy needed for application such as locating a person using a cell phone for a 911 call. A new protocol for WiFi, IEEE 802.11mc, provides for round-trip time measurement with nanosecond resolution. Knowing the position of several access points and the distance to them should provide all the information needed to solve for the position of the user. But the problem is more interesting than that, since round-trip time can be considerably longer than expected due to the high relative permittivity of typical building materials. We’ll discuss this and related issues, such as good placement of access points for low “dilution of accuracy”.  The method will be demonstrated using an app for an Android phone and a few Wifi access points located in the lecture hall.


Berthold K.P. Horn is a Professor of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology (MIT). He received the B.Sc.Eng. degree from the University of the Witwatersrand in 1965 and the S.M. and Ph.D. degrees from MIT in 1968 and 1970, respectively. He is the author, coauthor or editor of books on the programming language LISP and machine vision, including Robot Vision and Shape from Shading.

Dr. Horn was awarded the Rank Prize for pioneering work leading to practical vision systems in 1989 and was elected a Fellow of the American Association of Artificial Intelligence in 1990 for significant contributions to Artificial Intelligence. He was elected to the National Academy of Engineering in 2002 and received the Azriel Rosenfeld Lifetime Achievement Award from the IEEE Computer Society for pioneering work in early vision in 2009. His current research interests include machine vision, computational imaging and intelligent vehicles.

In the 1980s, Dr. Horn spent a sabbatical at the University of Hawaii, Manoa, and worked with Prof. Edward Weldon of the Electrical Engineering Department and Professor Hugh Hilden of the Department of Mathematics. This collaboration led to a now widely referenced paper on a closed-form method for absolute orientation using unit quaternions.