An Updated Comparison of Four Low Earth Orbit Satellite Constellation Systems to Provide Global Broadband

Twenty years of technological improvements have raised once again the question of the economic viability of offering Internet access from space using non-geostationary orbits (NGSO). Trying to answer this question, many established satellite operators (e.g., SES, Telesat) and newcomers (e.g., SpaceX, Amazon) have recently filed applications for these types of constellations, with SES currently operating a NGSO constellation in MEO. The new architectures rely on thousands of high-throughput satellites, combined with an even-larger ground segment, which will compete with and complement the terrestrial Internet infrastructure where it is inefficient or non-existent.This paper provides an updated comparison of four of the largest LEO mega-constellations, namely Telesat’s, OneWeb’s, SpaceX’s, and Amazon’s, in terms of throughput estimation. First, we present the configuration of each constellation as described in their FCC filings (as of January 2021), including pending propositions. Then, we briefly describe the methodology and models used for the system performance analysis, which includes statistical analyses of each system’s throughput, as well as orbit dynamics and atmospheric conditions. Finally, we discuss the results and argue how the changes in the filings affected the overall throughput estimation and satellite efficiency, in terms of average capacity utilization.Despite having the fewest satellites, Telesat achieves a similar throughput as SpaceX thanks to their dual gateway connection and wider field of regard. OneWeb manages to achieve second-to-highest throughput thanks to their largest constellation, despite having the lowest satellite utilization. The reduction in minimum elevation angle and altitude improves SpaceX’s previous results in both total throughput and satellite utilization. Amazon achieves the highest throughput at around 53.4 Tbps, at the cost of a larger ground segment. Finally, all architectures benefit from the usage of ISL, achieving improvements between 13% and 42% when using 20 Gbps connections.