Underwater communication presents many challenges in order to transmit data with large bandwidth and over long distance and/or over a wide area. Indeed, water absorption, scattering and turbidity prevent radio waves to be used similarly as in air. Acoustic transmission has therefore been the standard technology for decades, but suffers from a very small bandwidth (less than 1 Mbps), whereas a video stream or conventional large data stream requires a bandwidth higher than 10Mbps. Free Space Optical systems have been developed and tested underwater lately taking advantage of the development of lasers and LEDS with wavelengths around 500nm. In this range, water absorption is minimal and optical communication range could theoretically reach 150m with a bandwidth in the tens of Mbps. Large distance communication and correct alignment between the transmitter and the receiver remain however challenging.
UC Berkeley researchers have developed a new method for long-distance and/or widearea underwater wireless communication using Autonomous Underwater Vehicles (AUVs) equipped with a Free Space Optical system allowing high bandwidth communication. The high stability and agility of the AUV allows to maintain a correct alignment between the receiver and the transmitter of two different AUVs keeping the data communication operational.