Efficient full duplex air to underwater communication using laser and acoustic links

Recent years have witnessed an increased interest in the applications of underwater acoustic networks (UWANs). The current research focuses on contemporary UWAN issues such as the limited acoustic bandwidth, the multi-path effect caused by signal reflections, efficient data dissemination given node mobility, etc. In legacy UWAN systems, floating nodes are used to interface the UWAN through radio links to off-water based stations and to and provide a global coordinate system for UWAN. However, such an approach could be impractical for extended missions, ineffective for rapid response scenarios, and/or undesirable for covert military operations. To address these issues and omitting the need of floating nodes, this proposal promotes the development of innovative architecture and reliable communication protocols for interfacing the underwater network via an airborne base-station (ABS). The research aims at establishing and maintaining a communication link to support the operation of underwater network where ABS can interface to UWAN. We propose developing protocols that will factor underwater dynamics and leveraging the optoacoustic (OA) effect to generate underwater acoustic signals. We aim to utilize such protocol to introduce a Global Positioning System (GPS) in the underwater environment that can be leveraged for localization and topology management. We intend to encode underwater acoustic signals by controlling the OA effect through directing airborne laser beams toward the water surface. The uplink is established by means of a coherent laser that will detect impinging and protrusion caused by an incident acoustic transmission from an underwater node onto the water surface. The main challenge is the underwater medium since this medium is categorized as being both dynamic and inhomogeneous. Inhomogeneity of the underwater medium is mainly due to the temperature variation of the sea water with depth while dynamicity is observed in the temperature change at specific depth due to solar radiation, wind, and underwater currents. The inhomogeneity causes the acoustic signal to refract and change direction while dynamicity suggests the propagation paths observed of an established channel at different time may change. We aim to sense the underwater inhomogeneity by leveraging established communication link