Hybrid Testbed for Leo Mega-Constellations: Ground Station Placement Study

Abstract

Evaluating end-to-end network performance in Low Earth Orbit (LEO) satellite mega-constellations requires systemlevel testbeds capable of capturing extreme satellite mobility, rapidly evolving topologies, and realistic protocol behavior at scale. Existing approaches rely on analytical models or eventdriven simulations that abstract away protocol-level interactions and time-varying orbital dynamics. This paper demonstrates the capability of our developing hybrid emulation-simulation testbed for end-to-end system-level evaluation of LEO megaconstellations, using ground station placement as a representative case study. The testbed instantiates each satellite as an isolated network namespace with a real protocol stack, computes all propagation delays from instantaneous satellite distances and the speed of light, and evaluates performance across a full orbital period rather than a single static snapshot. Using the testbed, we evaluate four placement strategies across Starlink Gen1, OneWeb, and Amazon Kuiper architectures. The results reveal previously unreported system-level insights, including latency saturation beyond approximately 100 ground stations, a reduction in orbital sensitivity from 10-15 ms to less than 1 ms, and fundamental performance differences between ISL-enabled and non-ISL architectures.