Optical-acoustic hybrid network toward real-time video streaming for mobile underwater sensors

Underwater sensor networking is generally regarded as an emerging technology in conducting oceanic exploration and research in an automated and effective manner. As underwater operations become more sophisticated and Autonomous Underwater Vehicles (AUVs) become more advanced, there is an increasing demand for real-time video streaming from AUVs to remotely steer them and to probe the environment. However, real-time video streaming requires high bandwidth. To help overcome this obstacle, we propose a hybrid solution that combines acoustic and optical communications. In our hybrid solution, optics provide good quality real-time video streaming. Acoustic maintains a “thin” channel for the network topology and transmission control. The acoustic channel is also used for still frame video delivery when the optical channel fails. In particular, we enable optical communications by acoustic-assisted alignment and use acoustic communications as a backup when the optical signal is interrupted. The main contribution of this research is to enable reliable, real-time video streaming without underwater optical cables. Another important contribution is the smooth transition between the acoustic and optical video delivery mode, by leveraging image processing algorithms to compress the key frames before transmitting them on the acoustic channel.