Comparison of TCP Congestion Control Performance over a Satellite Network

While satellite Internet bitrates have increased, latency can still degrade TCP performance. Realistic assessment of TCP over satellites is lacking, typically done by simulation or emulation, if at all. This paper presents experiments comparing four TCP congestion control algorithms – BBR, Cubic, Hybla and PCC – on a commercial satellite network. Analysis shows similar steady state bitrates for all, but with significant differences in start-up throughputs and round-trip times caused by queuing of packets in flight. Power analysis combining throughput and latency shows during steady state, PCC is the most powerful, due to relatively high throughputs and consistent, relatively low round-trip times, while for small downloads Hybla is the most powerful, due to fast throughput ramp-ups. BBR generally fares similarly to Cubic in both cases.