Frequency scaling of Ku-band signal for rain attenuation prediction and radio link applications over Akure, Nigeria

Abstract

To get the best performance for a broadband wireless access, this research aims to scale a Ku-band real-time rain attenuation data to higher frequencies and estimate the degree of fading that can be observed under such conditions. Data of simultaneous measurement of satellite radio beacons and rainfall parameters, carried out between January 2017 and December 2018, at Physics Department, Federal University of Technology (07.17°N, 05.18°E, 358 m) Akure, were used for the work. The radio beacon measurement, of horizontally polarized Eutelsat W4/W7 satellite signals at 12.245-GHz frequency, and received through a 90-cm parabolic antenna positioned at 53-deg elevation angle, was conducted at 1 s integration time using Tektronix Y400 NetTek spectrum analyzer. Measurement of rainfall parameters was done at 1-min sampling intervals using Davis Vantage Vue automatic weather station, which is co-located with the receiving antenna of the satellite receiver unit. Comparing measured and estimated attenuation values at 12.245 GHz for 1%, 0.1%, and 0.01% exceedance margins result in about 64%, 40%, and 55% relative error, respectively. Similarly, relative error values between estimated and scaled attenuation values for the same exceedance margins are 72%, 53%, and 27% for 16-GHz frequency, respectively, with similar values for the 20-, 30-, and 40-GHz frequencies as well. A power-law relationship between measured rain attenuation and rain rate was developed and used to generate a location-specific expression for computing rain attenuation. This was equally found to give better performance than the International Telecommunication Union model. The results obtained in this work provide useful information for radio engineers on the rain-induced attenuation needed for the design of radio communication system that can withstand poor weather conditions.