On the scattering-induced fading for optical wireless links through seawater: statistical characterization and its applications

Recent research has shown that an accurate underwater channel characterization is necessary for underwater optical wireless communication (UOWC) in order to improve its current limitations related to the achievable data rate and the link distance, as required in undersea optical networks. This paper presents a new statistical model to characterize the scattering effect in terms of a fading never considered before. In this way, the probability density function of the scattering-induced fading channel is derived by means of a Gamma distribution by using only one degree of freedom in clear ocean and coastal waters. The developed fading model is employed to compute the performance of UOWC systems in terms of bit error rate and outage probability along with turbulence-induced fading modeled by a Weibull distribution. The results prove that smaller diversity order values are achieved when scattering-induced fading is the dominant effect, i.e., when the condition sigma(2)(s)>1/ss(1) is satisfied, where sigma(2)(s) and beta(1) are parameters related to the Gamma and Weibull distributions, respectively. Moreover, the optical power penalty due to scattering-induced fading is analytically evaluated in several turbulence conditions to provide a deeper insight. Optical power penalty values of up to 6 dB and 9 dB are achieved when compared with no scattering scenarios at moderate distances for clear ocean and coastal waters. As a key feature, scattering should be always considered in terms of fading for future designs of advanced UOWC systems. The analytical results are verified by Monte Carlo simulations. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Recent research emphasizes the importance of accurate underwater channel characterization for improving the performance of underwater optical wireless communication systems. A new fading model is proposed to analyze the impact of scattering-induced fading on system performance. Results show that smaller diversity order values are achieved when considering scattering-induced fading, highlighting the need to always consider scattering in fading analysis for advanced UOWC system designs.