Analysis of LoRa Signal Characteristics at Maize and Cocoa Crops in Tropical Regions

In this research work, experimental propagation models were developed for LoRa wireless networks operating at the 900 MHz ISM band, covering maize and cocoa crops at ESPOL University GEA-Farm (Agroproductive Experimentation Farm) located in the tropical city of Guayaquil, Ecuador. Each terminal node with its corresponding antenna reported the Received Signal Strength Indicator (RSSI) data to a central processing unit, including a gateway and a data broker made with open hardware and software components. The maize crop had a density of 3.25 plants /m
²
, with an average plant height of 2 meters, and a total area of 13,034 m
²
. On the other side, the cocoa crop had a density of 0. 67 plants / m
²
, with an average height of 1.6 meters, and a total area of 5,100 m
²
. The resulting experimental propagation models were compared with empirical ones such as: Standford University Interim (SUI), Weissberger, ECC-33, and the ITU-R Early Vegetation Model. In addition, it was implemented a correlation analysis to preliminarily assess the influence of climatic variables over the signal strength.