海洋湍流下波长分集无线光通信系统性能分析

由于海水的吸收、散射衰减以及海洋湍流效应会引起水下无线光通信（Underwater wireless optical communication，UWOC）系统接收端光信号的闪烁，导致UWOC系统传输性能下降。基于Gamma-gamma分布的海洋湍流信道模型，根据海洋湍流参数和各向异性因子表示的等效结构参数，推导出波长分集UWOC系统中断概率（Outage probability，OP）与平均误码率（Bit error rate，BER）封闭表达式。研究分析随着各向异性因子的增加，具有不同波长分集阶的水下无线光通信系统中断概率与平均误码率的变化，比较接收端使用最佳组合（Optimal combining，OC）与等增益组合（Equal gain combining，EGC）技术的水下无线光通信系统平均误码率，并仿真不同海洋湍流参数、传输距离对波长分集UWOC系统性能的影响。数值结果表明，随着各向异性因子的增加，海洋湍流对水下无线光通信系统产生的影响逐渐减弱，使用波长分集技术的UWOC系统比无波长分集技术的UWOC系统中断概率与平均误码率明显改善。

Performance analysis of wavelength diversity wireless optical communication system in ocean turbulence

Due to seawater absorption, scattering attenuation and ocean turbulence effects, the optical signal at the receiving end of the underwater wireless optical communication (UWOC) system will flicker. The flickering signal will result in a decrease in the transmission performance of the UWOC system. Based on the Gamma-gamma distribution of the ocean turbulence channel model, according to the equivalent structural parameters represented by ocean turbulence parameters and anisotropy factors, the closed expressions of the outage probability (OP) and the average bit error rate (BER) of the wavelength diversity UWOC system were derived. With the increase of the anisotropy factor, the changes in the outage probability and the average bit error rate of UWOC system with different wavelength diversity orders were analyzed. The average bit error rate difference of the UWOC system between the optimal combining (OC) and the equal gain combining (EGC) used at the receiving end technology were compared, and the influence of different ocean turbulence parameters and transmission distances on the performance of the wavelength diversity UWOC system was simulated. The numerical results show that the ocean turbulence effect on the UWOC system gradually weakens with the increase of the anisotropy factor. The UWOC system with wavelength diversity technology has significantly improved the outage probability and the average bit error rate than the UWOC system without wavelength diversity technology.