Monte-Carlo based non-line-of-sight underwater wireless optical communication channel modeling and system performance analysis under turbulence
Peng Yue, XiangRu Wang, Shan Xu, YunLong Li
TL;DR
This work addresses the challenge of modeling non-line-of-sight underwater wireless optical channels by jointly accounting for sea-surface reflection and particle scattering under turbulence. It develops a Monte Carlo framework to obtain the fading-free impulse response $h_0(t)$ for the joint channel and introduces a weighted double gamma function (WDGF) to fit the derived CIR, with $h(t)=\frac{C_{1}C_{2}^{-\alpha}}{\Gamma(\alpha)}\Delta t^{\alpha-1}e^{-\Delta t/C_{2}}+\frac{C_{3}C_{4}^{-\beta}}{\Gamma(\beta)}\Delta t^{\beta-1}e^{-\Delta t/C_{4}}$ and $\Delta t=t-t_{0}$. Turbulence is modeled via a lognormal fading $\tilde h=\exp(2X)$ with $X\sim\mathcal{N}(\mu_X,\sigma_X^2)$ and $\mu_X=-\sigma_X^2$, where $\sigma_X^2=0.25\ln(1+\sigma_I^2)$ for weak turbulence. The WDGF model is fitted to MC results with RMSE typically below 0.05, enabling closed-form BER and outage analyses for coastal and harbor waters under varying link distances and receiver FOVs. The results offer design guidance for NLOS UWOC systems and quantify performance under turbulence, informing parameter choices like transmit beamwidth and aperture field-of-view. These contributions provide a practical framework for evaluating and optimizing NLOS UWOC links in realistic underwater environments.
Abstract
Compared with line-of-sight (LOS) communication, nonline-of-sight (NLOS) underwater wireless optical communication (UWOC) systems have garnered extensive attention because of their heightened suitability for the intricate and dynamic underwater environment. In the NLOS channel, photons can reach the receiver by sea surface reflection or particle scattering. However, research lacks comprehensive channel models that incorporate sea surface reflection and particle scattering. Moreover, the presence of ocean turbulence introduces random fluctuations in the received optical signal based on the average light intensity. Consequently, this paper adopts the Monte Carlo simulation method (MCS) to solve the fading-free impulse response of the joint reflection-scattering channel. Furthermore, a weighted double gamma function (WDGF) is proposed to characterize the channel impulse response (CIR). Based on the closed CIR model, the average bit error rate and the performance of the interruption probability of the UWOC system under turbulence are analyzed. The conclusions obtained are intended to assist in the design and performance evaluation of NLOS UWOC systems.