Latency Analysis for Satellite IoT in Remote Areas

Internet of Things (IoT) systems are becoming an interesting solution to be deployed in remote areas of the Earth with no terrestrial Internet connectivity and no energy supply. This paper investigates the cases where Low Earth Orbit (LEO) satellites are used to collect data from dispersed sensors with low density, thus supporting the so-called Internet of Remote Things (IoRT). This approach can be useful for monitoring the environment and smart agriculture on a large scale. In these circumstances, relatively cheap CubeSats systems can collect the sensor data transmitted by the ground IoT nodes. This work focuses on the feasibility of the link budget referring to LoRa radio technology for direct transmissions from ground nodes to LEO satellites. Since CubeSats have a very simple technology onboard, they do not use inter-satellite links. Therefore, a satellite collecting data from a ground node needs to store the data onboard until it reaches the visibility of a ground gateway station to forward these data onto the Internet. Focusing on this Store & Forward (S&F) approach, we have investigated the latency performance for the data delivery into the Internet considering both Kepler and the Swarm Technology CubeSat constellations and the impact of node location and minimum elevation angle allowed by the system.