A ground-to-air free-space optical link is studied for a hovering unmanned aerial vehicle (UAV) having multiple rotors. For this UAV, a four-quadrant array of photodetectors is used at the optical receiver to alleviate the adverse effect of hovering fluctuations by enlarging the receiver field-of-view. Extensive mathematical analysis is conducted to evaluate the beam tracking performance under the random effects of hovering fluctuations. The accuracy of the derived analytical expressions is corroborated by performing Monte-Carlo simulations. It is shown that the performance of such links depends heavily on the random fluctuations of hovering UAV, and, for each level of instability there is an optimal size for the array that minimizes the tracking error probability

中文翻译：

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带有四象限探测器的无人机辅助 FSO 链路的波束跟踪

研究了具有多个旋翼的悬停无人机 (UAV) 的地对空自由空间光链路。对于这种无人机，在光接收器处使用了四象限光电探测器阵列，通过扩大接收器视场来减轻悬停波动的不利影响。进行了广泛的数学分析，以评估悬停波动随机效应下的波束跟踪性能。派生的分析表达式的准确性通过执行蒙特卡洛模拟得到证实。结果表明，此类链路的性能在很大程度上取决于悬停无人机的随机波动，并且对于每个不稳定级别，都有一个最佳阵列尺寸，以最小化跟踪错误概率