大气环境严重影响了自由空间光通信系统的性能。考虑到天气环境、大气湍流以及指向性误差等因素对激光通信的影响,建立了联合信道统计模型,并利用Meijer-G函数推导出基于开关键控调制的自由空间光通信系统的平均误码率、平均信道容量和中断概率等性能参数及其闭合表达式。在不同类型的M湍流、不同的归一化指向性误差以及能见度为5 km和20 km天气的联合信道条件下,对系统性能参数进行仿真与分析。结果表明:指向性误差越小,通信系统性能参数受湍流影响越大;指向性误差越大,越可能存在最佳光束发散角使得通信系统达到最佳性能。

The atmospheric environment seriously affects performance of the free space optical communication system. Considering the influence of weather environment, atmospheric turbulence and directivity error on laser communication, we establish a joint channel statistical model, and derive the performance parameters of free space optical communication system based on on-off keying modulation, such as average bit error rate, average channel capacity and outage probability and their closed expressions, using Meijer-G function. The performance parameters of the system are simulated and analyzed under different M turbulences, different normalized pointing errors and visibilities of 5 km and 20 km. The results show that the smaller the directivity error, the greater the influence of turbulence on the performance parameters of the communication systems; the bigger the directivity error, the more likely for a best beam divergence angle existing to make the communication system achieve the best performance.