Diffuse-LOS Optical Wireless Communication Across Wavy Water-Air-Interface Using UVA Light

Underwater Wireless Optical Communication (UWOC) holds significant implications in the realms of marine scientific observation, marine military security, and marine resource utilization. Overcoming the challenges associated with cross-medium information transmission represents a pivotal research frontier within the domain of underwater Internet of Things (IoT). This paper investigates the across water-air-interface ultraviolet light uplink communication in the presence of waves. Different degrees of diffuse-line-of-sight and different sizes of waves are studied in the communication link to assess their impact on transmission performance. Using non-return-to-zero on-off keying (NRZ-OOK) modulation, a data transmission of 17.4 Mbit/s is achieved with a lateral displacement of 5 cm in still water, and 17.1 Mbit/s data transmission is achieved under aligned 12 mm wave amplitude condition. A method is proposed to reduce the dependence on relay in across water-air-interface communication when the optical transmitter and receiver are not aligned, and the effectiveness of using ultraviolet light communication under large wave conditions is demonstrated. Bit error rate and received optical power indicate that increasing wave size and deviation of the transceivers both result in channel attenuation in the water-air-interface channel, thus degrading link performance.