LeoTCP: Low-Latency and High-Throughput Data Transport for LEO Satellite Networks

Low-Earth Orbit (LEO) satellite networks consist of thousands of satellites orbiting the Earth, enabling low-latency and high-throughput communications across the globe. Such networks present unprecedented challenges due to their dynamic nature, which state-of-the-art data transport protocols do not address. These challenges include: (1) non-congestive latency variation and loss, caused by continuous satellite movement and fluctuating link quality due to weather effects; (2) transient hotspots leading to buffer build-up, latency inflation, and potential packet loss; and (3) frequent handovers, which may result in temporary connectivity loss and re-routing through paths with unknown congestion and delay characteristics. In this paper, we introduce LeoTCP, a novel data transport protocol designed specifically to address these challenges. LeoTCP leverages in-network telemetry (INT) to gather congestion information on a per-hop basis. Using this information, LeoTCP (1) minimises both buffer occupancy and latency for end users, (2) maximises application throughput and network utilisation, and (3) swiftly reacts to network hotspots. We compare LeoTCP to state-of-the-art data transport protocols using a LEO satellite simulation model and targeted micro-benchmarks, both based on OMNeT++/INET. The simulation model captures RTT dynamics in a simulated LEO satellite constellation, while the micro-benchmarks isolate key LEO-specific characteristics, including non-congestive latency variation and loss, path changes, and congestion hotspots. Our results demonstrate that LeoTCP significantly increases goodput compared to existing state-of-the-art approaches, while simultaneously minimising latency.