Millimeter Wave Propagation Loss In The Atmosphere And The Effect On 5G Communication

The problem of tropospheric propagation is a necessary factor of the scientific planning and design of ground-to-air communication systems.In order to make the 5G communication system reliable,it is necessary to analyze the influence of all factors on electromagnetic wave propagation path of in the troposphere.Propagation prediction is an important guarantee to ensure the communication of the system under bad weather conditions.Therefore,it is important to study the tropospheric propagation environment firstly when study the propagation of millimeter wave in the troposphere.Then it can provide a strong reference for the corresponding research and preventive measures to ensure the normal and efficient operation of the system communication.In this paper,the effects of oxygen molecules and water vapor molecules absorption on the radio wave are studied.Cloud,rainfall attenuation and scintillation are also be considered.A composite attenuation model is proposed.Combined with the path loss model under 5G communication condition,the total attenuation on line-of-sight and non-line-of-sight is calculated.Finally,the capacity and bit error rate on 5G communication are calculated.The main results of the research include: 1.Referring to the ITU Recommendation,using simple approximation and line-by-line accumulation to calculate transmission loss in the atmosphere with wider frequency range,which including the characteristic attenuation,zenith attenuation,high and low elevation angle attenuation.It is found that atmospheric gas absorption has a strong selectivity.The effects of pressure,temperature and water vapor density on the atmospheric gases attenuation are also analyzed.It indicates that they are all the factors that affected the atmospheric attenuation and the water vapor density is the most important one.2.Based on the ITU Recommendation,the characteristic attenuation of the millimeter wave in the cloud and fog is calculated with the Rayleigh approximation method.The attenuation and attenuation prediction of the cloud along the slant path are calculated and supplemented.Considering the influence of rainfall intensity,the characteristic attenuation,attenuation of the inclined path and the attenuation prediction are calculated.After analyzing the influence of the liquid water density and the rainfall rate on the attenuation,it is found that rainfall rate has the greatest influence on the attenuation at high frequency.3.Based on the ITU Recommendation,the change in refractive index due to humidity and temperature is considered,which resulting in scintillation attenuation when radio wave propagates in the atmosphere.There scintillation models including ITU,Karasawa and Vande Kamp are introduced and compared.Influence of each factor on the scintillation attenuation is analyzed.ITU scintillation attenuation model is supplemented and the calculated frequency is raised to 1000 GHz.ITU model also makes a prediction on attenuation.It is found that the scintillation attenuation value of the electromagnetic wave with low frequency or even up to 1000 GHz is very small and is almost negligible in the actual communication.4.Considering the complex attenuation caused by multi-source atmospheric,the prediction of compound attenuation model and the prediction of compound attenuation with the change of time percentage are proposed.Combined with the characteristics of 5G communication,the modified FS,modified SUI,CI,FI and Dual-slop path propagation loss model are introduced.Finally,the total path loss model considering the meteorological factors in urban is proposed and he capacity and bit error rate of the digital communication system are calculated.The results indicate that the path loss in two cases is related to frequency,antenna height,path length and path selection and the path loss exponent has the greatest influence.The results show the Dual-slop model is in good agreement with the actual measurement data and the capacity of 5G system is very large and the number of modulation has an vital effect on 5G communication.The number of modulation can be selected according to the specific situation.