LoRa LPWAN Channel modelling in palm oil plantation for smart agriculture applications

Abstract

The palm oil plantation is the main cash crop of tropical Asia and implementation of LPWAN (Low Power Wide Area Network) technologies for smart agriculture applications in palm oil plantations will benefit the palm oil industry in making more revenue. Prior to the implementation of LoRaWAN, it is important to investigate the propagation channel quality in palm oil foliage environment. The plantations are covered by densely scattered palm oil canopies which may cause significant propagation loss. To find the foliage loss the existing empirical foliage loss models are reviewed and a site specific pathloss model is proposed. This research attempts to characterize the LoRa 433MHz frequency channels for the available spreading factors (SF7-SF12) and Bandwidths (125 kHz, 250 kHz and 500 kHz). The LoRa channel modelling in terms of path-loss calculation uses empirical measurements of RSS (Received Signal Strength) in palm oil plantation located in Selangor, Malaysia. In this research, about 2700 LoS (line of sight) and 300 NLos (Non line of sight) propagation data are collected for pathloss modelling. Using the empirical data, a prediction model is constructed. The pathloss exponent for LoS propagation of the proposed prediction model is found 2.34 and 2.9 for 125 kHz -250 kHz bandwidth and 500 kHz bandwidth respectively. Again, for the NloS propagation links, attenuation per trunk is found 7.58dB, 7.04dB, 5.35dB, 5.02dB, 5.01dB, 5dB for SF7-SF12 respectively and attenuation per canopy is found 9.32dB, 7.96dB, 6.2dB, 5.89dB, 5.79dB, 5.45dB for SF7-SF12 respectively. Results indicate that the proposed multiwall model is found to be the better choice (avg. RMSE 2.74dB) when benchmarked with the existing empirical foliage loss models (Weissberger’s and ITU-R) to predict the pathloss in palm oil plantation.