El-Fikky Abd El-Rahman A, Eldin Maram Essam, Fayed Heba A, El Aziz Ahmed Abd, Shalaby Hossam M H, Aly Moustafa H
Appl Opt. 2019 Oct 20;58(30):8272-8281. doi: 10.1364/AO.58.008272.
In this paper, the impact of water channels under different communication link parameters is studied for underwater visible light communication (UVLC). The objective is to highlight the best results for non-line of sight (NLoS) communication links. In addition, NLoS links are studied under different parameters: LED colors, viewing angle, receiving angle, and data rates. The results are obtained and plotted using MATLAB simulation. The performance of the received power is first measured at different wavelengths and data rates. Then, the best results are further investigated at different viewing angles and receiving angles. The obtained results show that using cyan color provides more depth for the NLoS case, as well as a low bit error rate compared to the other colors. Most of the literature is concerned with unpractical configurations in underwater scenarios, such as an empty sea or assuming no human-object or blockage environment. We use the practical setup in Zemax Optics Studio to allow a precise description of ray tracing and high order of reflections inside a sea water environment. The channel impulse response (CIR) is obtained for static channel modeling, including a blockage environment to evaluate the best transmitters in sea water. Also, we are able to compare the average delay and the average delay spread of the source colors. The reflection characteristics of the sea water are considered as wavelength dependent. The CIR obtained by Zemax Solver and MATLAB indicates that cyan is the best source in sea water for different LED chips. Moreover, other previous studies assume perfect alignment scenarios between divers, which is not practical and not suitable for real channel gain results. Accordingly, we present a comprehensive dynamic channel modeling and characterization study for UVLC. Our study is based on Zemax programming language (ZPL) combined with Zemax Optics Studio. Using ZPL enables us to apply a mobility algorithm for divers and measure the channel gain variations due to random motion. We introduce a dynamic motion in a single-input single-output scenario and a single-input multiple-output scenario in the presence of blockage divers. Statistical analyses are studied for the appropriate distributions that can fit the data with various transmitter and receiver specifications. All dynamic scenarios are performed using cyan color in sea water, as it is proven to have satisfactory performance. The statistical results are beneficial for further analysis. As case studies, we consider various underwater scenarios, and the resulting parameters of statistical distributions can be used for future analysis in UVLC dynamic environments.
本文研究了不同通信链路参数下的水通道对水下可见光通信（UVLC）的影响。目的是突出非视距（NLoS）通信链路的最佳结果。此外，还研究了不同参数下的NLoS链路：LED颜色、视角、接收角和数据速率。使用MATLAB仿真获得结果并进行绘图。首先在不同波长和数据速率下测量接收功率的性能。然后，在不同视角和接收角下进一步研究最佳结果。所得结果表明，与其他颜色相比，使用青色可为非视距情况提供更大的深度，且误码率较低。大多数文献关注的是水下场景中不切实际的配置，例如空海或假设无人类物体或无障碍物的环境。我们在Zemax光学工作室中使用实际设置，以便精确描述海水环境中的光线追踪和高阶反射。针对静态信道建模获得信道冲激响应（CIR），包括用于评估海水中最佳发射器的障碍物环境。此外，我们能够比较源颜色的平均延迟和平均延迟扩展。海水的反射特性被视为与波长相关。由Zemax求解器和MATLAB获得的CIR表明，对于不同的LED芯片，青色是海水中的最佳光源。此外，其他先前的研究假设潜水员之间是完美对齐的场景，这在实际中并不实用，也不适用于实际信道增益结果。因此，我们针对UVLC提出了一项全面的动态信道建模与表征研究。我们的研究基于Zemax编程语言（ZPL）与Zemax光学工作室相结合。使用ZPL使我们能够为潜水员应用移动性算法，并测量由于随机运动引起的信道增益变化。我们在存在障碍物潜水员的单输入单输出场景和单输入多输出场景中引入动态运动。针对能够拟合具有各种发射器和接收器规格的数据的合适分布进行统计分析。所有动态场景均在海水中使用青色进行，因为已证明其具有令人满意的性能。统计结果有助于进一步分析。作为案例研究，我们考虑各种水下场景，所得统计分布参数可用于UVLC动态环境中的未来分析。
