湍流大气对无线光通信影响分析及解决方案

分析了湍流大气光传输特性,讨论了光信号闪烁对宽带光无线通信误码率的影响及解决方案。从湍流大气的经典功率谱模型与修正功率谱模型出发,分析了Rytov指数与光场波长的变化关系,讨论了其对传输光场强度起伏的影响,以及分别在球面波与平面波时的差异。从实验上模拟考察了湍流大气对宽带光通信的影响,提出了一种新的从光链路上矫正波前畸变、减弱信号闪烁进而降低通信系统误码率的技术方案。该方案基于遗传算法和无模型盲优化的方式,以Zernike多项式系数为向量,对波前畸变进行编码,根据畸变波前的Zernike多项式的系数实现波前重构。其特点是没有预先测量波前相位畸变信息,而是采用施特列耳比作为遗传算法的适应度评判标准,通过优化达到最佳的波前畸变补偿效果。分析结果表明,该方案对中等强度以下的湍流大气光传输具有明显改善效果。

Analysis and resolution for wireless optical communication in turbulent atmosphere

According to the classical and modified model of power spectrum for turbulent atmosphere,the variation of Rytov index in different wavelenths,and the Rytov index impacted on intensity fluctuation of light beam,also the differences of Rytov index in the case of plane wave and spherical wave were analyzed and discussed.In order to overcome those effects of turbulent atmosphere,the influence of the turbulence atmosphere on width band transfer system was simulated in experiment,and a novel technique that can correct the distortion of wavefront and eliminate the scintillation from optical path was presented.In this scheme,the wavefront sensor could be omitted comparing with the traditional adaptive optics,practically,the phase aberration information of beam was predicted by using a statistical method and the distortion wavefront was corrected by taking the Strehl ratio as the performance metric,and based on a real number encoding genetic algorithm,by means of the coefficients vector set of Zernike polynomials and modeless blind optimization,the reconfiguration of distortion wavefront were realized at middle intensity turbulent atmosphere.It improves the performances of communication system efficiently.