This study focuses on the analysis and modeling of microwave line-of-sight (LoS) link fade margin for mobile communication networks in Nigeria. It aims to evaluate the fade margin, which is the major drawback associated with microwave LoS link operation, especially in tropical regions. The fade margin is the amount of excess signal power above the minimum required to maintain a reliable communication link in microwave LoS systems. Three states in Nigeria were examined: Kogi State, Edo State, and Imo State, over a period of two years. The parameters affecting fade-margin evaluation in mobile communication networks were determined, and the related data were measured using Web LCT software installed on a laptop. The received signal data for nine links were collected from March 2020 to February 2022, along with nine link-budget parameters and local rain data from Nigeria Meteorological Agency (NiMet) covering two years (2020–2022). Chebil’s model was used to determine the 0.01% rain rate (mm/hr) from the recorded rain volume (mm). The rain attenuation (Ar) for the nine links was calculated using the field data obtained. A mathematical model was developed and translated into a block diagram using MATLAB Simulink. The developed fade margin was compared with the existing fade margin, and a GUI was created based on the developed fade-margin model, accommodating all possible variable inputs. The results showed that the fade margin is not linear but undulating due to the influence of atmospheric factors such as haze, smoke, mist, dust, rain, fumes or smog, equipment malfunction, atmospheric temperature, and mountainous environments. The variation between the existing fade-margin model and the developed model is attributed to rain attenuation, which was intentionally considered while developing the new fade-margin model suitable for Nigeria’s tropical region. A fade-margin calculator was also designed to compute the developed fade margin, taking into account key parameters such as link distance, frequency, antenna polarization, transmit power, antenna gain, and regional rain rate. This developed fade-margin model will be particularly useful to Line-of-Sight (LoS) microwave link engineers in achieving reliable and efficient fade-margin estimation, ultimately improving the quality of service of microwave communication networks.
Idim et al. (Thu,) studied this question.