11/4/2014 Susan Mumm, Media Specialist
Written by Susan Mumm, Media Specialist
Two papers from Gao’s group garnered Best Presentation of the Session Awards at the recent Institute of Navigation Global Navigation Satellite System (ION GNSS+) conference.
Gao’s graduat student Daniel Chou presented the first award-wining paper on “Robust GPS-Based Timing for Phasor Measurement Units, A Position-Information-Aided Vector Tracking Approach.”
The use of Phasor Measurement Units (PMUs) to monitor electrical oscillations within power grids is ramping up because of the stability PMUs provide. While 500 were in use in March 2012, about 1,000 networked PMUs are projected by the end of this year.
GPS robustness and reliability directly influence how PMUs do their jobs: PMU measurements are time-stamped using GPS receivers. Such GPS-based timing provides a common time reference to the oscillation phase measurements across a wide area. However, GPS receivers are vulnerable to interfering electromagnetic fields, jamming, and spoofing attacks (situations in which the attacker falsifies the data received).
Gao’s group has counteracted these vulnerabilities through a technique called Position-Information-Aided (P.I.A.) Vector Tracking. This approach utilizes the fact that GPS receivers in PMUs are stationary in position. A vector tracking method is used to predict GPS code and carrier measurements by projecting the positions and velocities of GPS satellites on their line-of-sight directions to enhance tracking performance. In a field test, Gao and her students have demonstrated improved robustness against noise and jamming, as well as the ability to successfully detect record-and-replay spoofing attacks.
Gao’s postdoctoral research associate, Liang Heng, and Chou as second author presented the group’s second award-winning paper on “Cooperative GPS Signal Authentication from Unreliable Peers.” This paper introduces a signal authentication architecture based on a network of cooperative receivers. A receiver in the network crosschecks its signal with those received by others in the network to detect spoofing attacks. The approach explores both the network and the geographical redundancy of the networked GPS receivers.
The group conducted field experiments in San Francisco, California and Rantoul, Illinois as well as on the University of Illinois campus to check the theory’s performance in urban canyon and open space terrain, and under static and moving conditions.
“We feel honored to have received these awards. They are definitely encouraging for the students in my research group”, Gao said.