Sea-Trial of a Real-Time Underwater Wireless Optical Communication System in Shallow Turbid Water With Wave Fluctuation

Underwater wireless optical communication (UWOC) is attracting increasing interests and attention due to high communication bandwidth compared to underwater wireless acoustic communication (UWAC). However, as UWAC has been widely used for undersea research and developments, most UWOC studies are still conducted in ideal laboratory condition through offline signal processing tests, lacking real-time sea trial studies in realistic environment, where the influence of sea wave fluctuation and water turbidity on the system performance cannot be neglected. Moreover, unlike deep-sea UWOC systems under calm and clean sea conditions, shallow seawater UWOC performance is affected by wave fluctuation, high turbidity and other severe factors, limiting the communication distance and stability. In this article we demonstrate a real-time UWOC system, with 6.25 Mbps real-time communication data rate and large receiver dynamic range of 84.32 dB. Sea-trial experiment is conducted in shallow turbid seawater under condition of 0.2443 m-1 water attenuation, sea state 4 and 1.5 m wave height. Under such condition, the UWOC system realizes 6.25 Mbps Ethernet packet transmission over 80 m communication distance, supporting real-time video streaming with 640×360 resolution. To the best of our knowledge, this is currently the longest communication distance of real-time UWOC based video transmission in shallow water sea-trial. The received optical power scintillation index caused by wave fluctuation in sea-trial is 0.024, which result in 0.019% packets loss, and 7.5% of BER statistics exceeding the FEC threshold of 3.8×10-3.