2009 Research Summary

RF Time of Flight Ranging for Wireless Network Localization

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Kristofer Pister and Steven Michael Lanzisera

Berkeley Sensor and Actuator Center

An enabling technology for large scale sensor networks is the ability to determine a sensor node’s location after deployment. Some applications, such as inventory management, use sensors that move regularly, and this spatial information is crucial to the network's operation.

A device to wirelessly measure the distance between two network nodes using an RF transceiver will be developed. The distance measurement is performed by calculating a cross correlation between a received and an expected signal. Methods for reducing the effects of noise, clock offset, and multipath propagation have been studied, and mitigation techniques have been implemented. We have demonstrated round-trip time of flight (TOF) ranging using an FPGA, 2.4 GHz radio, and a custom PCB. Meter level accuracy has been demonstrated both indoors and outdoors. The end goal is to provide low power, accurate, self-contained, ad hoc localization to mobile sensor nodes.

A new platform, dubbed Waldo by KP, is under development for RF TOF ranging experiments. A location-aware wireless network using Waldo devices is currently being tested in order to fully demonstrate the capabilities of the proposed system. Technique development to mitigate the effects of multipath interference is ongoing.

[1]

S. Lanzisera and K. Pister, "Burst Mode Two-Way Ranging with Cramer-Rao Bound Noise Performance," Proceedings of the IEEE Global Communications Conference (GLOBECOM), December 2008.

[2]

S. Lanzisera, D. Lin, and K. Pister, "RF Time of Flight Ranging for Wireless Sensor Network Localization," Workshop on Intelligent Solutions in Embedded Systems (WISES), June 2006.