  Localization of underwater networks is important in many military and civil
applications. Because GPS receivers do not work below the water surface,
traditional localization methods form a relative topology of underwater nodes
(UWNs) and utilize either anchor nodes or floating gateways with dual
transceivers in order to determine global coordinates. However, these methods
introduce logistical complications and security risks in deploying the anchor
and/or surface gateways. This paper tackles such an issue by proposing new
localization techniques which can remotely localize UWNs using optoacoustic
signals. In our approach, GPS coordinates are transmitted from air to the UWN
via creating an underwater temporary isotropic acoustic transmitter with the
optoacoustic process. We analyze the process of controlling the shape and size
of the plasma to create the isotropic acoustic transmitter and experimentally
validate the generation of isotropic acoustic signals. Then two methods of
localization are proposed for static and dynamic UWNs. Finally, the simulation
results with experimental values show the effectiveness of our approach.
Comparing to the traditional techniques, our approach achieves the same
accuracy without using any surface or underwater anchor nodes.
