SatPipe: Deterministic TCP Adaptation for Highly Dynamic LEO Satellite Networks

Low-Earth-Orbit (LEO) satellite networks (satnets) hold significant potential for providing global internet access with high throughput and low latency. However, the high mobility of the satellites and the associated handovers cause high dynamics at the link layer, which in turn degrades end-to-end network throughput and stability. In this work, we first present a measurement profiling of the handover behaviors of the Starlink satnet, so as to better understand its dynamics and accurately determine handover timings with millisecond precision. We then introduce Satpipe, a new mechanism to enhance TCP and make it robust against satnet dynamics. Satpipe exposes the link layer handover schedule to the TCP sender, which then adapts to the link interruptions in a deterministic rather than trial-and-error manner. Our implementation and experiments over Starlink indicate that Satpipe delivers an average throughput gain of 9.4% to 38%, achieves up to a 127.8% enhancement in the 10% lower throughput, and exhibits a 24.7% reduction in retransmission ratio, compared to the state-of-the-art TCP BBR. This advantage further propagates to the application layer, leading to a 10.8% increase in bitrate and 33.5% reduction in rebuffering time for video streaming applications.