International Research Journal of Education and Technology

As IoT applications expand rapidly, devices are increasingly being deployed in remote areas requiring satellite networks, particularly Low-Earth Orbit (LEO) satellites, to deliver global connectivity for use cases such as disaster response, precision agriculture, and environmental monitoring. A key challenge in direct-to-satellite (DtS)-IoT is enabling energy-efficient and spectrum-efficient multiple access. This paper introduces two novel scheduling methods for DtS-IoT networks, both derived from the LoRa to LEO satellite scheduling algorithm (SALSA), which allocates time slots on a first-come-first-served basis to minimize collisions. However, SALSA’s performance diminishes in high-density scenarios. The proposed techniques enhance uplink efficiency by utilizing multiple frequency channels and adjusting transmission scheduling within visibility windows, resulting in up to an 80% increase in system uplink efficiency with smaller packet sizes and more available channels. By combining the two approaches, system performance improves further, ensuring over 50% uplink efficiency across four, six, and eight channels.

Key Words: Direct-to-satellite IoT (DtS-IoT), Low-Earth Orbit (LEO) satellites, Multiple access scheduling, Uplink efficiency, LoRa to LEO satellite scheduling algorithm (SALSA).