|A 2002 change in Federal Communications Commission (FCC) regulations has opened the door to the use of ultra-wideband (UWB) technology for communications, which researchers believe might be useful in high-data-rate, low power communication systems.
Ultra-wideband is a technique used in radar applications that employs narrow, fast rise time pulses (typically less that 1 nsec.) rather than conventional modulated carrier signals. UWB pulses occupy a large frequency band and were previously restricted due to interference concerns.
Ultra-wideband has been proposed as a technique for tactical communication systems due to its low power spectral density and its immunity to interference (e.g., jamming) and multipath, said Mike Buehrer, who is investigating UWB propagation properties. It has also been proposed for commercial systems due to its ability to achieve large data rates in frequency bands allocated to other applications while ostensibly causing little to no interference to existing applications.
Buehrer outlined several issues that must be resolved before UWB can be used effectively, including limitations in the size and efficiency of wideband antennas, lack of understanding of the UWB channel, and absence of channel models for performance and link budget evaluation, and a lack of knowledge of the interaction of signal processing algorithms with other aspects of UWB system design. We have a lot to learn about UWB for communications, Buehrer said. Right now, we dont fully understand how the propagation of UWB signals will impact system design. The channel has a tremendous impact on the efficiency of the system design, and right now there is no consensus on how to model the UWB channel, he added.
ECE researchers with expertise in electromagnetics and wireless communications are collaborating on several UWB efforts, including a recently funded project for the Defense Advance Research Project Agency (DARPA). Initial UWB work involves characterizing the UWB channels and creating channel models for simulation, with plans to extend UWB investigations to antenna designs, communication system design, and developing signal processing approaches to maximize the energy efficiency of UWB systems.
Faculty members currently involved in UWB include Buehrer, Jeff Reed, Bill Davis, Ahmad Safaai-Jazi, Warren Stutzman, Sedki Riad, Charles Bostian, Dong Ha, and Dennis Sweeney.