Fabrication and Performance Evaluation of a LoRaWAN-Based Wireless Sensor Node for Greenhouse Environmental Monitoring

Greenhouse microclimates vary spatially, and thus, distributed environmental sensing is required; however, wired and short-range wireless networks are difficult to expand and maintain. In this study, a long-range wide-area network (LoRaWAN)-based wireless sensor node was designed, fabricated, and evaluated. Air temperature, relative humidity, carbon dioxide (CO2) concentration, and illuminance were encoded into one payload and transmitted through a gateway to a locally hosted network server. Environmental monitoring was conducted in a greenhouse simulator, and communication performance was evaluated through antenna-gain and node-density tests and an outdoor near-line-of-sight distance test (20–100 m). Packet delivery ratio (PDR), received signal strength indicator (RSSI), signal-to-noise ratio (SNR), and the server-side downlink enqueue-to-dispatch interval were analyzed. The node captured clear diurnal variations in all four variables. The 5 dBi antenna gave the highest observed PDR (100.00% with one and two nodes; 94.44% with four nodes). RSSI and SNR were comparatively stable from 20 to 60 m and deteriorated at 80 and 100 m. Under four-node Class C operation, the server-side downlink enqueue-to-dispatch interval ranged from 7 to 18 ms (mean 9.50 ms). This interval excluded LoRa radio airtime and end-node reception. The prototype demonstrated functional environmental monitoring in a small greenhouse simulator and preliminary communication performance with up to four nodes. The outdoor near-line-of-sight measurements provide site-specific propagation references; coverage and performance in commercial greenhouses remain to be validated.