Bidimensional ZCC/MD in underwater free space optics

The significance of non-terrestrial networks for ubiquitous connectivity in 6G systems has pro-voked substantial interest in underwater communication systems. Free space optics has garnered significant momentum in underwater communications owing to its high data rate. Nevertheless, it still faces restricted link distance, primarily driven by a notable increase in channel path loss attributed to absorption and scattering. These effects encompass factors such as chlorophyll, water-soluble salts, and minerals, and further compounded by fading induced by underwater optical turbulence. In our manuscript, a bidimensional ZCC/MD-OCDMA underwater free space optical system has been developed and evaluated under various underwater media. The assessment is conducted through the measurement of the bit error rate, Q-factor, and eye diagrams.