Ergodic Channel Capacity Analysis for Underwater OWC under Different Detection Schemes

Underwater Optical Wireless Communications (UOWC) are emerging as an intriguing technology that can provide several advantages as compared to acoustic and radio waves. High data rates and medium propagation ranges are the main benefits of UOWC, although they suffer from absorption and scattering-induced attenuation losses. There are severa statistical distributions that model the effect of underwate turbulence on optical wireless communication, and how to model the UOWC channel with higher accuracy is still a topic to investigate. In this paper, we present a unified channel model for UOWC, which works both for heterodyne and Intensity Modulated/Direct Detection (IM/DD) schemes. A closed-form expression of channel capacity is then derived including the combined effect of attenuation, turbulence, and pointing error Numerical results show the channel capacity is strongly affected by geometrical parameters, as well as the water turbulence level. Also, the benefits of heterodyne detection over IM/DD is evinced