Gamma-Gamma大气湍流中部分相干光通信系统性能研究

部分相干光在湍流大气中传输时，可以有效抑制湍流所引起的光强闪烁效应，从而改善通信链路性能。针对Gamma-Gamma大气湍流信道模型和部分相干光的光束特性，得到了采用OOK调制方式下部分相干光通信系统的平均误码率、中断概率和平均信道容量三个性能指标的解析表达式；在此基础上，分析了光束的空间相干长度和通信距离对通信链路的性能影响。计算结果表明，在相同的大气湍流条件和传输距离下，随着部分相干光的空间相干长度的减小，系统的误码率和中断概率逐步降低，在平均信噪比为30 dB时，系统的误码率可以达到10-5，中断概率低于10-6；另外，系统的平均信道容量会随着光束相干长度的减小而增加，在信噪比等于12 dB时，平均信道容量达到3.8 b/sHz-1。分析结果为部分相干光在湍流大气中实现可靠通信提供了理论依据。

Performance analysis of partially coherent optical communication system in Gamma-Gamma atmospheric turbulence

When a partially coherent beam is transmitted in turbulent atmosphere channel, the optical intensity scintillation effect caused by atmospheric turbulence can be effectively suppressed, and accordingly performance of communication link is improved. According to Gamma-Gamma atmospheric channel model and characteristics of partially coherent beams, the analytic expressions of average bit error rate(BER), outage probability and average channel capacity were obtained for partially coherent optical communication system. Based on these results, the influence of spatial coherence length and communication distance on performance of communication link was analyzed. Numerical results show that as the spatial coherence length of a partially coherent beam decreases, the system BER and outage probability decrease gradually under the same atmospheric turbulence conditions and transmission distance, and the outage probability is lower than 10-6 and system BER is 10-5, when average signal-to-noise ratio (SNR) is 30 dB; Meanwhile, as the spatial coherence length of the partially coherent beam decreases, average channel capacity of the system increases, and the average channel capacity is up to 3.8 b/sHz-1 when SNR is 12 dB. The analytical results provide a theoretical basis for the realization of the communication of partially coherent light in the turbulent atmosphere.