Experimental Study on Underwater Optical Wireless Channel Models

When a laser beam propagates underwater, it attenuates because of absorption, scattering, and turbulence; this results in light power attenuation and light intensity fluctuation. Considering that communication links have different water speeds, directions, and distances, an underwater optical wireless channel model is proposed to conduct field measurements in river and ocean nearshore waters. The light intensity fluctuation, received light power loss, and underwater structure constant were measured and analyzed in different water areas. The results showed that rivers have weak turbulence and offshore waters have moderate turbulence. The higher the water speed, the greater the scintillation index of the received optical signal power and the more unstable the signal. When transmitting horizontally, the scintillation index of the received optical signal power is independent of the water direction; the greater the scintillation index of the received optical signal power, the more unstable the signal.