Bandwidth Efficient Cooperative TDOA Computation for Multicarrier Signals of Opportunity

Source localization, the problem of determining the physical location of an acoustic or wireless emitter, is commonly encountered in sensor networks which are attempting to locate and track an emitter. Similarly, in navigation systems that do not rely on the global positioning system (GPS), ldquosignals of opportunityrdquo (existing wireless infrastructure) can be used as ad hoc navigation beacons, and the goal is to determine their location relative to a receiver and thus deduce the receiver´s position. These two research problems have a very similar mathematical structure. Specifically, in either the source localization or navigation problem, one common approach relies on time difference of arrival (TDOA) measurements to multiple sensors. In this paper, we investigate a bandwidth efficient method of TDOA computation when the signals of opportunity use multicarrier modulation. By exploiting the structure of the multicarrier transmission, much less information needs to be exchanged between sensors compared to the standard cross correlation approach. Analytic and simulation results quantify the performance of the proposed algorithm as a function of the signal-to-noise ratio (SNR) and the bandwidth between the sensors.