In general, a buoy relay is used to connect the underwater communication to the terrestrial network over a radio or optical wireless communication (OWC) link. The use of relay deployment may pose security and deployment issues. This paper investigates the feasibility of direct air-to-underwater (A2UW) communication from an over-the-sea OWC system to an underwater submarine without deploying a relaying node. We analyze the statistical performance of the direct transmission over the combined channel fading effect of atmospheric turbulence, random fog, air-to-water interface, oceanic turbulence, and pointing errors. We develop novel analytical expressions for the probability density function (PDF) and cumulative distribution function (CDF) of the resultant signal-to-noise ratio (SNR) in terms of bivariate Meijer-G and Fox-H functions. We use the derived statistical results to analyze the system performance by providing exact and asymptotic results of the outage probability in terms of system parameters. We use computer simulations to demonstrate the performance of direct A2UW transmissions compared to the relay-assisted system.

翻译：一般而言,浮标中继器用于通过无线电或光学无线通信连接水下通信与地面网络连接,使用中继部署可能带来安全和部署问题。本文件调查了从一个海面OW系统直接从一个海面OW系统向一个水下潜水艇直接空对水通信的可行性,而没有部署中继节点。我们分析了大气动荡、随机雾、空对水界面、海洋动荡和指针错误的综合通道衰减效应的直接传输的统计性能。我们用衍生的统计结果分析系统性能,提供系统参数参数方面外延概率的精确和微量结果。我们用计算机模拟来显示与中继系统相比的直接A2W传输的性能。