Performance of heterodyne differential phase-shift-keying underwater wireless optical communication systems in gamma-gamma-distributed turbulence.

The analytical expressions for the average bit error rate and the outage probability of a heterodyne differential phase-shift-keying underwater wireless optical communication (UWOC) system are derived with proper consideration of all of the channel-degrading effects, including absorption, scattering, and turbulence-induced fading. The scintillation index of a spherical wave is evaluated in order to quantify the underwater system performance in a strong turbulence regime. The spherical wave propagating through the strong underwater turbulence environment is modeled as gamma-gamma distribution. Then, the system performance is simulated for various variations of the underwater turbulence, i.e., the rate of dissipation of kinetic energy per unit mass of fluid, the ratio of temperature to salinity contributions to the refractive index spectrum, and the UWOC system link length. The results show that the analytical expressions for describing the system performance are valid.