Performance analysis of underwater wireless optical communication systems over a wide range of optical turbulence

Abstract

The propagation of optical signal under water is affected by three major degrading phenomena, namely absorption, scattering, and turbulence. The statistical distribution of turbulence-induced fading though has not yet been well characterized. In this paper, in order to investigate the effect of different probability density functions (PDFs) proposed for the statistical behavior of fading under water, we evaluate the performance of underwater wireless optical communication (UWOC) systems with respect to the well-known statistical distributions for the optical turbulence such as lognormal, Gamma, K, Weibull, and exponentiated Weibull distributions. For the sake of accuracy, we adopt a general channel model where both absorption and scattering effects are appropriately taken into account based on the Monte Carlo (MC) numerical method, and consider the fading effect as a multiplicative coefficient with the aforementioned PDFs. We derive the closed-form expressions for the average bit error rate (BER) and outage probability, as the system performance metrics, with respect to all of the channel degrading effects and the aforementioned statistical distributions. Our results demonstrate that as the turbulence strength, measured by the scintillation index value, increases, the gap between the system performance predicted by different statistical distributions becomes more, and this gap mainly appears in the form of changing the slope of average BER or outage probability curves versus the average transmitted power per bit. This further emphasizes the importance of accurate channel models for the design of UWOC systems.