Effects of Suspended Material on the Bit Error Ratio of Underwater Wireless Optical Links

Visible light communication (VLC) in the underwater environment has the potential to significantly enhance the performance of underwater networks by improving energy efficiency and channel capacities. This study investigates how suspended particulates affect the Bit Error Ratio (BER) in VLC links. A Literature review, series of simulations and practical experiments were conducted using a test tank and an optical communication system to evaluate received power characteristics and BER performance over short-range links through water with varying levels of particulate matter. The study also explored the impact of forward error correction (FEC) techniques, including Reed-Solomon and Hamming codes, to assess their effectiveness in improving link reliability. The results showed that, as expected, the red wavelength laser diode outperformed the green wavelength laser diode over discrete link distances in the scattering medium. Regarding BER and FEC, the cloudy water environment exacerbated BER issues. However, the Reed-Solomon code solved the errors to successfully recover the original data across the link in both clear and cloudy water, whereas the Hamming code reduced errors, but not sufficiently to eliminate all error propagation. Thus, the Reed-Solomon code proved to be the most effective in both clear and cloudy waters. Despite this, the experiment highlighted the inherent challenges of maintaining a reliable VLC link, as significant BER remained even in clear water with short-range communication.