Propagation Models for VHF Conventional Land Mobile Radio Systems in Cauca and Valle del Cauca Colombia

Colombia must strengthen its mission-critical communication infrastructure. Therefore, an orderly and legal operation of the current and future Conventional Land Mobile Radio (CLMR) systems is essential to protect these systems against interference and ensure high-quality service provision. In interference analysis, the choice of a propagation model significantly impacts the estimated levels of desired and interfering signals, which determines the minimum Frequency Distance (FD) separation required for these systems. Consequently, defining a simple empirical propagation loss model that accurately describes the attenuation behavior of CLMR system signals under real operating conditions in various regions of the departments of Cauca and Valle del Cauca, Colombia, is crucial. This study presents such a model. A received power level measurement campaign was conducted on the uplink of real systems, considering Andean, valley, and urban propagation scenarios with line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. The experimental results reveal significant variability in the signal measurements.