Performance Analysis Of Satellite-to-ground Communication Link Based On Multi-aperture Coherent Optical Receiver

Compared with the microwave communication,free space optical communication has the advantages such as high transmission capacity,high transmission rate,long transmission distance,better information security and rich spectrum resource.In free space optical communication,the beam is affected by turbulence and weather conditions when transmitted in the atmospheric channel,while spatial diversity can effectively suppress channel fading,increase output signal-to-noise ratio(SNR),improve communication system performance.Furthermore,they have the advantages such as robustness to single element failures,easy to maintain and upgrade.This paper focuses on the performance of optical communication systems for multi-aperture coherent optical receivers.By using the Gamma-Gamma distribution model and the Beer–Lambert Law(BLL)under the atmospheric turbulence and atmospheric attenuation loss,a combined atmospheric channel model is established,which can be used to analyze the influence of intensity scintillation,beam wandering and various weather conditions(fog,cloud,rain,snow,etc.).Based on this,bit error rate(BER)model for multi-aperture coherent optical receivers is established,considering the maximum ratio combining(MRC),equal gain combining(EGC)and selection combining(SC),and the aperture averaging effect produced by the actual optical antenna size.Based on the model,the average received SNR in the uplink and downlink optical communication to satisfy certain BER requirement is calculated.Comparing the BER performance differences for the three combined techniques.Analyzing the influence of weather conditions and actual optical antenna aperture size on system performance.Contrasting the system performance between the uplink and downlink.Compared with the previous researches,this paper considers more factors in practice.The BER model of atmospheric channel and multi-aperture coherent optical receivers is improved.The research results have good practical guiding significance for designing optical communication systems based on multi-aperture coherent optical receivers.