冰云对量子卫星通信性能的影响

Influence of Ice Cloud on Performance of Quantum Satellite Communication

冰云由微小的冰晶粒子组成,一般出现在6 km以上的高空,冰晶粒子和光量子信号相互作用会对量子卫星通信链路造成严重影响。为了研究冰晶粒子对量子卫星通信性能的影响,首先,根据冰云光散射模型和米散射理论,定义了冰云内冰晶粒子的平均消光系数,并建立了链路衰减系数、冰云冰水含量(IWC)和量子信号在冰云内传输距离的关系;然后,针对振幅阻尼信道,建立了信道容量、信道平均保真度、信道生存函数、信道误码率和冰云IWC以及量子信号在冰云内传输距离的关系。理论分析和仿真实验结果表明,当量子信号在冰云内的传输距离为20 km时,随着冰云IWC的增加,链路衰减因子从4.6 dB增加到14.7 dB,量子信道容量由0.250 bit/s减小到0.089 bit/s,信道平均保真度也急剧降低,生存函数值由1.00减少到0.58,量子信道误码率从0.015增大到0.075。这表明冰云内的冰晶粒子对量子卫星的通信质量有明显影响,为了提高量子卫星通信系统的可靠性,需根据冰云的相关参数,自适应调整量子卫星通信系统的参数。

Ice cloud is composed of tiny ice crystal particles,which generally appear at an altitude of more than 6 km.The interaction between ice crystal particles and light quantum signals will seriously affect the quantum satellite communication link.To study the influence of the ice crystal particles on the performance of quantum satellite communication,in this paper,first,according to the ice cloud light scattering model and the Mie scattering theory,the average extinction coefficient of the ice particles in the ice cloud is defined,and relationship between the link attenuation coefficient,ice cloud ice water content(IWC)and the transmission distance of quantum signal in the ice cloud are established;then,for the amplitude damping channel,the relationship between channel capacity,channel average fidelity,channel survival function,channel error rate and ice cloud IWC and the transmission distance of quantum signal in ice cloud are established.Theoretical analysis and simulation results show that when the transmission distance of quantum signal in ice cloud is 20 km,with the increase of ice cloud IWC,the link attenuation factor increases from 4.6 dB to 14.7 dB,the quantum channel capacity decreases from 0.250 bit/s to 0.089 bit/s,the average channel fidelity decreases sharply,the survival function decreases from 1.00 to 0.58,and the quantum channel error rate increases from 0.015 to 0.075.This shows that the ice crystal particles in the ice cloud have a significant impact on the communication quality of the quantum satellite.In order to improve the reliability of the quantum satellite communication system,the parameters of the quantum satellite communication system should be adjusted adaptively according to the relevant parameters of the ice cloud.