Underwater localization with time-synchronization and propagation speed uncertainties

Underwater localization is a key element in most underwater communication applications. Since GPS signals highly attenuate in water, accurate ranging based techniques for localization need to be developed. In this paper we describe a sequential algorithm for time-synchronization and localization in the underwater acoustic channel. We consider the realistic case where nodes are not time-synchronized and the sound speed in water is unknown, and formalize the localization problem as a sequence of two linear estimation problems. Simulation results demonstrate that our algorithm compensates for time-synchronization and signal propagation speed uncertainties, and achieves good localization accuracy using only two anchor nodes.