5G毫米波短距离链路雨衰减特性分析

雨衰减严重影响第5代(the 5th Generation，5G)移动通信系统性能.在路径长度小于1 km的短距离链路情况下，现有雨衰减预测模型调整因子大于1，导致预测雨衰减随路径变短而增大，无法支撑毫米波短距离链路系统设计.通过分析国际电信联盟无线电通信部(Radiocommunication Sector of International Telecommunication Union，ITU-R)短距离链路雨衰减试验数据，发现湿天线衰减与路径雨衰减相当，得到毫米波短距离链路必须考虑湿天线衰减的结论.建立了湿天线衰减与降雨率的关系模型，分频段对模型参数进行了拟合，拟合结果与实测数据吻合得较好.提出了考虑湿天线衰减的短距离雨衰减建模新思路，可解决短距离雨衰减预测问题.研究结果有助于提高5G毫米波系统余量设计的可靠性.

Rain attenuation characterization on 5G millimeter wave links with short distances

Rain attenuation can severely affect the performance of the 5th generation(5G)mobile communication millimeter wave systems.By using the existing rain attenuation prediction models,we observed an anomalous phenomenon that when the link is shorter than 1 km,the adjustment factor is bigger than 1,which means that the predicted rain attenuation increases in spite of the path length shortened.By analysing the measured rain attenuation data supplied by ITU-R,we found that the effect of wet antenna attenuation is comparable with that of the path rain attenuation,thus it must be considered in short links.A wet antenna attenuation model related to the rainfall rate is proposed,and parameters in different frequencies are given,which fit well with the measured data.The method also provide a novel thought for short-link rain attenuation modeling by taking wet antenna attenuation into account,which can solve the anomalous phenomenon mentioned above.Results of this research helps to enhance the reliability of the margin design of 5G millimeter wave systems.