A direct-to-ground architecture for supporting commercial communications from the International Space Station

We outline the first steps of an effort to start defining a communications architecture for supporting broadband data communications from the International Space Station. We focus on a direct-to-ground architecture, which could serve as an intermediate solution to satisfy the near term communications needs of commercial experiments and payloads on the ISS and overcome certain limitations of the current ISS communications infrastructure. We address three communications options and evaluate an architecture for the direct-to-ground option, focusing on a particular user´s requirements, communications links, and coverage availability. We also discuss system, mobility support and protocol issues that need to be addressed for this solution to be a feasible alternative.