Invisible Hands Behind 3.5 GHz Spectrum Sharing

There has been considerable discussion surrounding the barriers to spectrum sharing in the literature. Among those is the ‘trust gap’ that exists, according to the PCAST report. Trust is a complex human construct that significantly includes risk. In this paper, we examine the risks faced by the different user classes proposed by the FCC for sharing in the 3.5 GHz band. We argue that the “invisible hands” of spectrum sharing in this band is the balance between spectrum sharing gain and associated risks. We find that both gains and risks can be linked to the distance between incumbents’ systems and Citizen Broadband Radio Services (CBRS)’ systems. The risk portfolio is linked to spectrum rights that each tier has, since the rights they have determine risks and risk mitigation strategies. We further propose a model to calculate spectrum sharing utilities for different tiers. The optimized utility determines the distance between incumbents and CBRS systems.