Cooperative self-localization in asynchronous sensors networks based on TOA from transmitters at unknown locations

We consider self-localization in an ad-hoc, asynchronous sensors network. A mobile beacon transmits a short wideband signal from a few locations, unknown to the sensors. Each of the sensors receives the transmissions and estimates their Times of Arrival (TOAs) relative to its own timebase, which has an unknown relative synchronization offset. If the positions of the beacon were known, each sensor could estimate its own time-offset and position. Since the beacon's positions are unknown, the sensors need to collaborate in order to estimate these positions along with their own. We propose a collaborative iterative scheme, where in each iteration each sensor announces its current estimate of the beacon's positions, along with an associated uncertainty covariance matrix. This information is received by neighboring sensors, and each sensor exploits the received information to refine its own estimates of the beacon's positions, as well as of its own time-offset and position. We show simulation results indicating successful self-localization using this scheme.