The Evaluation of Modulation Techniques for Underwater Wireless Optical Communications

Currently, there are lots of efforts at using underwater vehicles, gliders and moorings for the spatial and temporal measurements in oceanography research. Sensor data collected by these platforms is usually internally recorded and then transmitted via a cable or wireless communication. Traditional acoustic links are fundamentally bandwidth limited to low rates of bit per second (bps). Optical methods are well posed to provide an alternative solution for high bandwidth communications in undersea. In this paper, we examined several modulation technologies for undersea environment application. Through modeling and simulation, the advantages and limitations of these modulating configurations are discussed. It is demonstrated that the pulse position modulation (PPM) is better suited for low powered undersea systems and the phase shift keying (PSK) yields the best performance in term of bandwidth and error performance with poor power efficiency.