Performance Analysis of Radio Prediction Tools for the Determination of Diffraction Losses and Under-Coverage in some Mountainous Topologies of Northern Nigeria.

Abstract

Signal under-coverage due to diffraction losses, is fundamentally considered to be responsible for the hues and cries of communities residing behind mountainous topologies in Taraba and Niger State. Performance analyses of these radio tools are rudimentary for technical radio dimensioning and optimization. The epicenter of this study is to predict the depth of diffraction losses and under-coverage in mountainous areas of the study. To achieve this, an Open Source Geographical Resources Analysis Support System (GRASS) and other conventional diffraction models were employed. The result indicated that the transmitted radio signals were received via the mechanism of diffraction, as the mountain was found to obstruct the signal line-of-sight (LOS) and the ensuing effective ellipsoids of the Fresnel Zones in the analysis. Consequently, it was apparent that there was deep under-coverage in all the radio cells of the study location, as illustrated in the maps created with ArcGIS. The depth of under-coverage in Taraba State was relatively more severe than Niger State. Empirically, the skip distances of the shadow zone cast by the mountains for both States were 35.8km and 29.92km respectively. However, for ease of prediction in analogous topology and to cater to the discrepancies of the conventional models of diffraction used in this work, linear regression models were fitted to predict the measure of received signal strength (RSS) level and diffraction losses. In evaluating the validity of these models, it was realized that the measured and the calculated values were incongruent.