An experimental LoRa performance evaluation in tree farm

Deployment of internet of things (IoT) devices, wireless sensors, and sensor networks, in agriculture can be a great help in monitoring environment and growing crops; and having a network to support those devices is necessary to successfully utilize those resources. Recently, low-power wide area network (LPWAN) have been recognized as an appropriate technology for agriculture use. LoRa is a representative network of low-power wide area network (LPWAN). It can be applied to IoT for agriculture due to its long range and low power capabilities. LoRa network performance is highly affected by physical layer parameters and the environment. While LPWANs have been around for a number of years, they are still considered an emerging technology and have had few scientific studies performed. Currently, most studies have shown LoRa communication capabilities in urban, mountainous, and maritime areas, with little focus on agriculture use cases. Tree farming is a long-term investment, requiring careful monitoring to mitigate loss; therefore, this paper provides an analysis about the impact of variant physical layer parameters on performance of LoRa networks in a tree farm. Overall, the LoRa communication range was smaller than the theoretically expected range. Some PHY factors, spreading factor and coding rate, showed a clear impact on LoRa performance. Actual data reliability was inconsistent at varying distances and PHY configurations, unlike the consistency found in the RSSI reported by the radios. Additional experiments show the Fresnel Zone still affects LoRa networks. All experiments were performed in an Indiana rural tree plantation in the United States. Each node was set differently by modulating spreading factor, bandwidth and coding rate using 915MHz and 13 dBm transmit power at variant distance.