中文摘要：

大气湍流引起的闪烁效应会严重影响大气光通信系统的性能。自适应判决阈值技术虽然可以有效改善大气光通信系统的误码率（BER）,但是难以进行实时应用。提出了一种根据各种参数统计值,将阈值设置为常量的阈值优化方法。主要考虑乘性高斯噪声并假设闪烁满足对数正态分布,分析了湍流信道中大气光通信系统的最优常量阈值,并将数值分析结果与弱湍流条件下的实验数据进行对比。对比的结果显示,最优常量阈值方法是有效可行的,相对于自适应阈值的性能降低也是可以接受的。分析还显示,在忽略孔径平均效应条件下,最优常量阈值主要取决于对数光强起伏方差和平均接收光功率,而其他参数的影响基本可以忽略。基于分析结果,提出了可以在实际应用中估计最优常量阈值的非线性模型。

英文摘要：

Scintillation caused by atmospheric turbulence impairs the performance of the atmospheric optical communication system. Bit error rate （BER） of an atmospheric optical communication system can be improved by using an adaptive detection threshold, which is difficult to implement in real time. As a sub-optimum method, optimizing the threshold to a constant value according to statistics of parameters was proposed. Assuming multiplicative Gaussian noise and lognormal scintillation, the optimum constant threshold of an atmospheric optical communication in turbulence channel was analyzed. The result of numerical analysis was compared with experimental data obtained in weak turbulence. Results of experiment and numerical analysis show that optimizing constant threshold is necessary and the performance degradation compared to adaptive thresholding is acceptable. Neglecting aperture-averaging effects, the dependence of the optimum constant threshold on log amplitude variance and average received signal power was analyzed and the influence of other parameters was proved to be negligible. Based on previous analysis, a non-linear model was proposed to estimate the optimum constant threshold in pracuce