降雪对地表附近自由空间量子信道的影响及参数仿真

量子通信具有覆盖面广、安全保密的优势,是当前通信领域国内外的研究热点.在自由空间量子通信过程中,光量子信号需要在地表上空一定高度进行传输,因此各种环境因素,例如降雪、沙尘暴、降雨、雾霾、浮尘等,不可避免地会影响量子通信性能.然而,迄今为止,降雪对地表附近自由空间量子信道影响的研究尚未展开.为此,根据降雪的强度,将降雪分...

Influence of snowfall on free-space quantum channel near earth surface and parameter simulation

Quantum communication has the advantages of wide coverage and security,and is currently a hot research topic in the field of communication.In the process of free space quantum communication,quantum signals need transmitting at a certain height above the surface.Various environmental factors in free space,such as snowfall,sandstorms,rainfall,haze and floating dust,will inevitably affect quantum communication performance.However,so far,the influence of snowfall on the performance of quantum channels in free space near the surface has not been investigated.Thus,according to the intensity of snowfall,the snowfall is divided into four levels:light snow(S1),medium snow(S2), heavy snow(S3) and blizzard(S1).When the snow is falling in the air,it has an energy absorption effect on the light quantum signal,which is called the extinction effect.The different intensities of snow extinction have different effects on free space optical quantum signal.In this paper,first,a mathematical model for the extinction effects on optical quantum signal at different levels of snowfall is presented;then the quantitative relationship between snowfall and free space extinction attenuation,as well as the relationship between snowfall and channel limit survival function is established,channel capacities under different snowfall intensities,and quantum bit error rate are also given.Finally,the mathematical models of snowfall intensity,transmission distance and link attenuation,amplitude damping channel capacity,channel survival function and channel error rate are established.Simulation results show that when the snowfall intensity is 2.1 mm/d(S1) and the transmission distance is 2.2 km,the communication link attenuation is0.0362,the channel capacity is 0.7745,the channel survival function is 0.2329,and the channel error rate is0.0105.When the snowfall intensity is 3.8 mm/d(S2) and the transmission distance is 3.5 km,the communication link attenuation is 0.1326,the channel capacity is 0.4922,the channel survival function is0.2099,and the channel error rate is 0.019.Thus,different snowfall intensity has different influence on the performance of free space quantum communication.Therefore,in practical applications,the communication parameters should be adjusted adaptively based on the snowfall intensity to improve the reliability of free space quantum communication.