| Due to the advantages of high bandwidth, good secrecy, and strong anti-interference ability, wireless laser communication has become a research hotspot in the field of communications. The intensity scintillation, beam wander, beam spreading and angle-of-arrival fluctuation caused by atmospheric turbulence, seriously affect the performance of laser communication system. In order to ensure the stability of communication system, it is significant to research the influence of atmospheric turbulence.The paper introduced the basic theory of coherent light diversity technology. Based on the modified Rytov method, using the logarithmic intensity variance, large and small scale, multi-beams transmission and arrays receivers can decrease the influence of atmospheric turbulence on BER and improve effectively the performance of laser communication system. Under the condition of turbulence, the BER of diversity is simulation. The SNR is25dB, compare BER of four beams with two beams, it can reduce0.5magnitude, BER of4apertures can reduce0.5magnitude than2apertures. For OOK and QPSK modulation, analysis and comparison of EGC, MRC and SC, considering the complexity of the signal energy utilization actual backend logic circuits, and EGC is more reliable and effective.Using the modified Rytov method to analyze the partially coherent light diversity technology. Under the same conditions, compared with the coherent light diversity, BER of the diversity of partially coherent light can reduce1.5magnitude. In the laboratory, turbulence simulation devices and the laser communication are firstly used to make the partially coherent optical communication system, a preliminary test of coherent optical communication and the BER under partially coherent optical communication in the presence of turbulence, Under the condition of same turbulence, the experimental results show that partially coherent optical communication had much better performance than coherent optical communication. |
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