Influences of wind and rain on radio wave propagation in foliated fixed wireless access at 5.8 GHz

Abstract

Movement of objects due to wind and rain in the vicinity of fixed wireless access introduces an adverse environment for high frequency radio wave propagation. In recent years, fixed wireless access deployed in suburban and rural areas are surrounded by large number of trees and hills. Although the transmitter and receiver of fixed wireless access remain in stationary positions, movement of trees in this foliated fixed wireless access would scatter, diffract and absorb the wireless signal causing signal fading. In this study, the focus was on the measurement temporal scale of the received signal strength in foliated fixed wireless access operating at the 5.8 GHz frequency of the Unlicensed National Information Infrastructure band. Based on the temporal scale of the measured received signal strength profiles of three different links comprising one line-of-sight and two non line-of-sight links, it was observed that line-of-sight link worked well even when it rained. The existence of trees in the vicinity of the transmission path caused signal deterioration where the received signal strength faded from 3 dB to 16 dB as the rain intensity increased. The wetness in the trees caused by rain had affected the received signal strength. To characterize the measured received signal strength, statistical characterization of the combined effects of several typical weather phenomena often experienced in a tropical region was also presented. The Rician distribution was used to characterize the fast fading effect due to both wind and rain. A smaller K-factor of the distribution represented more intense wind and rain conditions. Meanwhile, Lognormal distribution was found to be suitable in describing the slow fading characteristics in a foliated channel. The work reported in this thesis has determined the effects of wind and rain in the deployment of fixed wireless access in foliated channel to ensure optimized links be provided for end users.