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The realization of efficient, robust, and adaptable applications for the emergent Internet of Underwater Things enables the sustainable and effective conservation and exploitation of our oceans and waterways. Recent advances have fo- cused on Orthogonal Frequency-Division Multiplexing (OFDM) physical layers for supporting applications requiring high data rates and swift adaptation to changing underwater conditions. This prompts the need of tools for testing new OFDM-enabled underwater solutions. To this aim, this paper presents the implementation and evaluation of an OFDM-based physical layer module for the popular underwater network simulator DESERT. We aim at modeling the flexibility of the software-defined acoustic SEANet modem by realizing OFDM features that can vary in time, including the number and the selection of subcarriers and their modulation on a per-transmission basis. We demonstrate the usage of the proposed module through the DESERT-based simulation of three simple OFDM-enabled cross-layer MAC protocols in underwater acoustic networks of different sizes. The diverse and detailed set of results are obtained by using our physical layer module simply and swiftly. Our results also confirm the advantages of using the OFDM technology in solutions for underwater networking in challenging environments. 

Underwater wireless communication and network- ing are becoming key enablers of a number of critical marine and underwater applications. Experimentation is underway, in controlled environments as well as at sea, that concerns the deployment of several underwater devices providing wireless communication capabilities to sensors of different nature. Con- trolling the deployment at sea of these devices, remotely and efficiently, is paramount for enabling expedite testing of hardware and protocol development. To address this need, this paper presents the design, development, and testing of a Smart Buoy for real-time remote access to underwater devices and for provision of power and extended computational capabilities. Experimental results are shown concerning the time needed to connect with the Smart Buoy, the power consumption of its operations, and the energy harvesting intake (via solar panels) in time. We also investigate the buoy lifetime when powered by solar panels and supporting acoustic modems over varying traffic scenarios.