Propagation studies at 5.8 GHZ within vegetated environment for point-to-multipoint applications

Abstract

This thesis presents an empirical study for fixed wireless links based on IEEE802.16 standard in vegetated residential environment. Simulation and field measurements were conducted for suburban microcell channel by utilising 5.8 GHz of Unlicensed National Information Infrastructure (UNII). A set of comprehensive measurement that covered 13 point-to-multipoint links surrounding Universiti Teknologi Malaysia were selected to investigate the impact of vegetation on propagating radio waves. The aim of this study is to develop a path loss model that incorporates vegetation effect. Received Signal Strength (RSS), Signal-to-Noise Ratio (SNR) and factors influencing performance of the signal strength are highlighted here. Performance of RSS during daytime and night is also evaluated. The accuracy of proposed prediction model is analysed which quantifies that path loss is proportional to the distance of tree to the receiver, size, density and number of trees within the vicinity of transmitting and receiving antennas. Observation found that terrain and external effect, such as wind will significantly affect the signal performance too. Depending on the dynamic characteristics of trees presence between the communication links, the measurement results show that the path loss is increased from 5.69 dB to 33.67 dB. The results obtained are compared to Free Space Loss model, Weissberger model, and ITU-R model. Those established models are used to validate the applicability result obtained by means of Root Mean Square Error (RMSE). In view of this research work, a good agreement of the proposed excess loss model achieves the smallest RMSE for links obstructed by a single tree, row of trees, row of trees and road as well as row of trees, road and building.