Integrating LEO Satellites and Multi-UAV Reinforcement Learning for Hybrid FSO/RF Non-Terrestrial Networks

Integrating low-altitude earth orbit (LEO) satellites (SATs) and unmanned aerial vehicles (UAVs) within a non-terrestrial network (NTN), we investigate the problem of forwarding packets between two faraway ground terminals through SAT and UAV relays using either radio-frequency (RF) or free-space op...

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Bibliographic Details
Published in:IEEE transactions on vehicular technology 2023-03, Vol.72 (3), p.3647-3662
Main Authors: Lee, Ju-Hyung, Park, Jihong, Bennis, Mehdi, Ko, Young-Chai
Format: Article
Language:English
Subjects:
Autonomous aerial vehicles
Deep learning
hybrid FSO/RF
LEO satellite
Links
Low altitude
Low earth orbits
Maximization
multi-agent deep reinforcement learning
Multiagent systems
Network topologies
non-terrestrial network
Optimization
Orbits
Radio frequency
Reinforcement learning
Relays
Satellites
Throughput
UAV
Unmanned aerial vehicles
Wireless communication
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Summary:Integrating low-altitude earth orbit (LEO) satellites (SATs) and unmanned aerial vehicles (UAVs) within a non-terrestrial network (NTN), we investigate the problem of forwarding packets between two faraway ground terminals through SAT and UAV relays using either radio-frequency (RF) or free-space optical (FSO) link. Towards maximizing the communication efficiency, the associations with orbiting SATs and the trajectories of UAVs should be optimized, which is challenging due to the time-varying network topology and a huge number of possible control actions. To overcome the difficulty, we lift this problem to multi-agent deep reinforcement learning with a novel action dimensionality reduction technique. Simulation results corroborate that our proposed SAT-UAV integrated scheme achieves 1.99x higher end-to-end sum throughput compared to a benchmark scheme with fixed ground relays. While improving the throughput, our proposed scheme also aims to reduce the UAV control energy, yielding 2.25x higher energy efficiency than a baseline method only maximizing the throughput. Lastly, thanks to utilizing hybrid FSO/RF links, the proposed scheme achieves up to 62.56x higher peak throughput and 21.09x higher worst-case throughput than the cases utilizing either RF or FSO links, highlighting the importance of co-designing SAT-UAV associations, UAV trajectories, and hybrid FSO/RF links in beyond-5 G NTNs.
ISSN:0018-9545
1939-9359
DOI:10.1109/TVT.2022.3220696