为了在现有条件下对无人机遂行对地光通信任务的调制传输速率有一个准确的衡量, 需要建立合适的机载光通信大气信道模型。首先划分空域范围, 将影响要素限定在对流层内; 之后基于对流层典型大气效应建立了综合影响模型, 又进一步建立了无人机对地光通信的信道传输模型。在现有条件下进行无人机参数设置, 并对不同高度条件下无人机对地光通信的有效信息总量进行仿真, 得到了遂行光通信任务的最佳通信高度为2 660 m; 在此高度条件下, 通过选取合适调制速率点对信道传输模型进行仿真。结合临界有效信息总量的设置及仿真结果, 在满足光通信系统反馈检验需求的基础上, 将无人机光通信临界调制速率需求锁定在1.12 Gbps。为现有条件下光通信调制系统的设计提供了评估标准, 具有较强的指导意义。

In order to have an accurate measure about modulation transmission rate of UAV′s optical communication tasks to ground in the current conditions, a channel model which is suitable for airborne atmospheric optical communication needs to be established. Firstly, the airspace range was divised, the influencing factors was limited in the troposphere. Then the comprehensive influence model was established based on tropospheric typical atmospheric effect, and further the channel transmission model was established under UAV′s optical communication to ground. Parameters setting about UAV was made under the existing conditions, and total amount of effective information was simulated under UAV′s optical communication to ground on different heights, the best height for carrying out optical communication tasks was obtained which was about 2 600 m. At this altitude, the channel transmission model was simulated by selecting appropriate modulation rate points. Combined with the critical effective total information′s setting and the simulation results of channel model, on the basis that the needs for feedback test about optical communication system was met, the critical modulation rate needs of UAV′s optical communication was locked in 1.12 Gbps. The result provides the evaluation standard for the design of the optical modulation system under existing conditions and it has a strong guiding significance.