Rain Rate Retrieval Test from Millimeter-wave Measurement in Beijing

There are many advantages of using millimeter-waves in present and future 5G communication networks: larger available bandwidth, the greater capacity to carry information and much smaller antennas. Millimeter-wave technology has also been considered as challenging. The main limitation is range. This is due to the channel characteristics of millimeter-wave spectrum, i.e. large path loss, impact of atmospheric absorption CO2, O2 and attenuation due to rain, water vapour, fog and snow. This paper presents our millimeter wave link measurement results in Beijing, China and studies of the atmospheric impacts on millimeter-wave transmission. We analyze the feasibility of assisting rainfall monitoring and retrieving rain rate from the propagation measurement. Compared to existing studies which mainly focus on rain rate retrieval from commercial microwave backhaul links, our measurement design is an exemplary LOS transmission link. Many existing studies use commercial microwave link data extracted from the operator's network performance monitoring platform, and the availability of such received signal level data is restricted to every 15 minutes or longer. In our a more controlled measurement, it enables and data to be recorded more frequently and instantaneous recordings are available. Our results show that the rain variations could also be revealed from link attenuation using transmission link in addition to backhaul links. We also conclude that in order to quantify the measurement uncertainty caused by fading, the received signal need to be monitored for a sufficient long period of time for a better estimate of the reference level.