无线光中继通信在弱湍流时的性能估计方法  

Approximations to the Performance of Wireless Optical Relaying Communications over Weak Turbulence Channels

作　　者：陈晓 胡晓英 CHEN Xiao;HU Xiao-ying(Shanghai Shenhe Energy Engineering Technology Company,Shanghai 200233,China)

机构地区：[1]上海申核能源工程技术有限公司,上海200233

出　　处：《光通信研究》2021年第1期58-62,共5页Study on Optical Communications

基　　金：国家重大专项大型先进压水堆及高温气冷堆核电站—CAP1400核电厂智能运维关键技术研究资助项目(2019ZX06002022)。

摘　　要：对数正态信道是描述弱湍流条件下无线光通信衰落的有力数学工具。然而精确的对数正态信道性能表达式带有无法化简的多重积分,难以揭示信道参数和性能的联系,不利于性能估计。针对该问题,Wilkinson和Fenton近似被广泛应用于对数正态信道的性能分析,但Wilkinson和Fenton近似的应用范围却缺乏标准,这导致了系统设计时对理论性能的错误预判。为此,文章基于原点矩的积分表达式讨论了Wilkinson和Fenton近似的特点,提出了基于Wilkinson和Fenton近似来估计自由空间光通信中继性能的方法,对比了Wilkinson和Fenton近似在此类性能分析中的适用范围。仿真结果表明,在中低信噪比情况下,Wilkinson比Fenton近似更准确;在高信噪比情况下,Fenton比Wilkinson近似更精确。此外,仿真结果还表明,Wilkinson近似方法的精度和对数正态信道的方差密切相关。Lognormal channel is a powerful mathematical tool in modeling fading effects for wireless optical communications over weak turbulence channels.However,exact analysis involving lognormal channels involves multi-fold integrals,which reveal little insights into the relation between the system performance and the channel parameters.Therefore,Wilkinson Approximation(WA)and Fenton Approximation(FA)are widely applied to approximate the performance of lognormal fading channels.However,their ranges of applications are not fully studied,which causes discrepancies in performance evaluations.In this work,we compare WA and FA based on the expressions of moments,and propose an approach to approximate the performance of Free-Space Optical Communications(FSO)relaying systems over the lognormal weak turbulence channels,and discuss the ranges of applications for WA and FA.It is shown that at low and medium Signal-to-Noise Ratio(SNR),error probability approximation based on WA is more accurate.However,at large SNR,Fenton’s approach will provide better approximation accuracy compared to the WA.Simulation results indicate that the approximation error depends on the discrepancies between the variances over FSO links as well as the scintillation level of the channels.

关 键 词：自由空间 激光通信 性能分析 湍流信道 对数正态信道 

分 类 号：TN929.12[电子电信—通信与信息系统]