IoT Traffic Allocation in Hybrid LEO-GEO Satellite Networks for Latency Minimization

Motivated by the advent of heterogeneous satellite networks comprised of satellites at different orbits, we study a scenario in which IoT devices that are in coverage of both, a low Earth orbit satellite (LEO) and a geostationary Earth orbit satellite (GEO), have sporadic and packetized transmissions via the satellite return channel. The uplink channels are orthogonal for the two satellite types and the transmission policy employed is slotted ALOHA with retransmissions. The average successful transmission latency is investigated and a latency-minimizing allocation is identified, which assigns the IoT devices among the two satellite types. Our results show that a careful allocation of the devices greatly reduces the average end-to-end latency when compared to 1) a system with a single GEO satellite and 2) a heterogeneous LEO-GEO system with a naïve allocation while avoiding congestion in the LEO access channel.