Integrating the Skies for 6G: Techno-Economic Considerations of LEO, HAPS, and UAV Technologies

The combination of airspace and non-terrestrial networks (combined ASN), leveraging low Earth orbit (LEO) satellites, high-altitude platform stations (HAPSs), and unmanned aerial vehicles (UAVs), creates a transformative 6G connectivity infrastructure. The envisioned architecture combines the strengths of these technologies in a hierarchical network, addressing coverage, especially in remote areas not served today. In this article, we conduct a techno-economic analysis of the non-terrestrial enabling technologies of combined ASN. First, we identify and categorize a set of use cases ranging from rural connectivity through maritime scenarios to augmenting terrestrial networks, which could be implemented with different combinations of LEO satellites, HAPSs, and UAVs. Second, we provide a detailed total cost of ownership (TCO) analysis for these technologies, and find that a LEO constellation plus well-controlled UAVs are fit to provide global connectivity (TCO of a LEO satellite is 1.5 million USD) and on-demand network augmentation (10 million USD of TCO to serve a densely populated city), while a HAPS is best suited for regionally focused services with a TCO figure of 4.4 million USD. Finally, we provide an overview of the technological, regulatory, and economic challenges of HAPS, and outline specialized use cases where HAPS might be a good alternative.