Design and development of a LoRa-based Ground Sensor Terminal for L-band satellite IoT applications

In remote equatorial regions such as Malaysia, reliable connectivity remains a critical challenge for Internet of Things (IoT) deployment, particularly in areas where terrestrial infrastructure is unavailable or unreliable. Despite the rapid growth of satellite-assisted IoT, the absence of validated design parameters, reproducible Ground Sensor Terminal architectures, and empirical performance data tailored to Malaysia’s equatorial environment introduces significant uncertainty in predicting reliable link budgets, operating margins, and end-to-end performance of hybrid LoRa–Iridium L-band IoT systems. This thesis presents a reproducible two-hop LoRa–Iridium GST architecture for equatorial deployment in which LoRa in the sub-GHz band is used exclusively for the terrestrial sensor-to-Ground Sensor Terminal (GST) link, while the GST provides the satellite backhaul via Iridium Short Burst Data in the L-band. This study aims to investigate and optimise the critical design parameters, develop a functional prototype, and experimentally validate the performance of a LoRa-based Ground Sensor Terminal (GST) for L-band satellite IoT applications. A Design–Develop–Research methodology is employed. The design stage involves theoretical link-budget estimation and Doppler shift analysis to establish feasible operating margins under low Earth orbit (LEO) satellite dynamics. A GST prototype is then developed using an ESP32-class microcontroller, an SX1262 LoRa transceiver, and a RockBLOCK Mk2 modem based on the Iridium 9602 chipset. Field evaluations assess system performance using Received Signal Strength Indicator (RSSI) and Signal-to-Noise Ratio (SNR) for the LoRa terrestrial link, and end-to-end node-to-server delay for the satellite backhaul, across varying distances and satellite pass conditions. Theoretical analysis indicates an Iridium uplink link margin of approximately 7.53 dB at an assumed 10.93 dBW EIRP, while Doppler analysis shows a typical frequency offset of ±2.2 kHz, with a worst-case of ±6.8 kHz. Experimental results confirm RSSI and SNR degradation with distance and reveal an inverse relationship between satellite signal strength and transmission delay. This study contributes a reproducible and experimentally validated two-hop LoRa–L-band Ground Sensor Terminal architecture with empirical RSSI, SNR, and end-to-end delay measurements under equatorial operating conditions. These findings provide an evidence-based foundation for the practical deployment of satellite-assisted IoT systems in equatorial regions, where terrestrial connectivity is limited and reliable low-power data delivery is required.