StarBundler: Middlebox for Satellite-Independent Delay Control in LEO Constellation

LEO constellations are expected to provide low-latency communications, which enables applications such as video streaming even in remote areas. To enable these applications, we need to suppress the delay on the satellite links and avoid congestion to meet their latency requirement. However, managing link delay between each satellite requires scalability for the increasing number of satellites. Moreover, the propagation delay variation in LEO satellite links makes it difficult to control the delay because it is hard to distinguish congestion-related delay and propagation delay. We propose StarBundler: a traffic control middlebox for satellite networks without managing the traffic at the satellite. StarBundler exchanges information about RTT and throughput between ground stations with each other and controls the latency between StarBundlers using congestion control that is not affected by propagation delay variation. Evaluation of a simulated satellite link shows that we can preserve delay and bandwidth between StarBundlers with variable link capacity and propagation delay. In particular, StarBundler can reduce the 95th percentile of end-to-end RTT by 61% compared to the case without it.