Enhancing Underwater Optical Communications Using Spatial Diversity MIMO

Underwater optical wireless communication faces significant challenges, such as scattering, absorption, and turbulence, hindering data transmission. This article proposes countering turbulence-induced fading by employing spatial diversity in underwater optical links (UWOC). It integrates absorption and scattering considerations into the analysis and utilizes Multiple-Input Multiple-Output (MIMO) systems with Orthogonal Frequency-Division Multiplexing (OFDM) and On-Off Keying (OOK) signaling. The Bit Error Rate (BER) in MIMO-OFDM-UWOC is analytically addressed with repetition coding and Maximum-Likelihood (ML) detection. The channel impulse response considers absorption, scattering, and weak oceanic turbulence through Monte Carlo (MC) simulations. A lognormal fading coefficient is introduced, resulting in a remarkable BER of 5.78x10-9 at 30 dBm power per bit and an 11 Mbps data rate. This contribution enhances underwater optical communication technology, promising improved data transmission in challenging underwater environments.