Generic empiric propagation model for low power wireless networks operating at the 868 MHz band in smart cities

The tremendous growth of low power wireless technologies oriented to smart city applications has conduced to evaluate the propagation aspects under typical communication scenarios in urban environments where in contrast to cellular technologies the transmitter and or the receiver antenna can be deployed at different heights near ground. Thus, the authors introduce a unified empiric parametrised propagation model with validated parameters from the measurements to study the propagation characteristics in near-ground scenarios. The proposed model considers the antenna´s height as well as external power losses because of objects that may block the line-of-sight to the receiver. The main results of this research demonstrate that in near-ground wireless links, the wireless range is severely reduced because of diffraction caused by ground. However, in scenarios where the receiver is always higher than the transmitter the diffraction is null and the path loss slope is less than free space, with the consequence of a considerably higher wireless range. The propagation model presented here is a valuable tool for network planning where typical cellular propagation models might not be appropriate.