给出了一种全光双跳自由空间光通信(FSO)系统的基本结构,建立了包含大气损耗、大气湍流和瞄准误差的复合衰落信道模型,考虑背景噪声和放大器自发辐射噪声对系统性能的影响,推导了在全部信道状态信息时,采用副载波强度调制全光中继系统的中断概率和误码率闭合表达式,对比分析了全光双跳FSO与直传链路的中断概率以及信噪比、源节点发射的光子数、光自由度等参数对系统中断概率及误码率的影响。仿真结果表明,全光双跳放大转发中继能够明显改善系统的性能。 The basic structure of an all-optical, double-hop free-space optical communication (FSO) system is given. A composite fading channel model including atmospheric loss, atmospheric turbulence and aiming error is established. Considering background noise and spontaneous emission noise of amplifier, Influence and deduce the closed-form expression of interrupt probability and bit error rate of sub-carrier intensity-modulated all-optical relay system when all the channel state information is deduced, and compare and analyze the interruption probability of all-optical double-hop FSO and direct-link link, Noise ratio, the number of photons emitted by the source node, the degree of freedom of light and other parameters on the system interrupt probability and bit error rate. Simulation results show that all-optical double-hop amplification and repeater relay can obviously improve system performance.