Positioning Error Analysis and Experiments on Underwater Optical Wireless Communication Induced by Light Beam Bending

For an underwater optical wireless communication (UOWC) system, alignment between transmitter and receiver is indispensable, which raises high requirements on the positioning technique. In the practical marine environment, light travels in a bending trajectory rather than in a straight line due to the non-uniformity of the refractive index of seawater, which leads to the position error. In this work, the position error under light beam bending due to refraction index variation is investigated concerning a UOWC system, and a simplified layered model is introduced to approximate the continuous refractive index variation in the practical ocean scenario. Besides, an approximated bending light path function is derived as well. Experimental results showed that a great consistency exists between the predicted positioning error and the measured one, and the potential causes of derivation between these results are further analyzed.