Coordinated UL/DL Multi-Beam Scheduling for Latency-Reduced Satellite Data Relay

Low Earth Orbit (LEO) satellite constellation systems are expected to be integrated with terrestrial networks for future communication services over wide areas. For real-time applications, direct data relay between users is effective to minimize the propagation delay via LEO satellites, where multi-beam control is an essential function in LEO satellites to efficiently allocate beam resources over the areas. However, no previous works considered the satellite’s buffer limitations and the differences in throughput between uplink (UL) and downlink (DL) which caused queuing delays. This paper proposes a coordinated UL/DL multi-beam scheduling to minimize the end-to-end latency of data relay by considering the available buffer space of the satellite and variations in UL/DL throughput due to satellite movement. An optimization problem is formulated for the scheduling design to minimize the end-to-end latency. We demonstrate with simulation results that the proposed scheduling method reduces the latency by 16.0%, compared to the conventional methods.