Abstract
We consider a three-tier spectrum sharing framework, recently adopted in the United States for the Citizens Broadband Radio Service, which enables commercial users to share this spectrum with the incumbent users. This sharing can be further assisted by environmental sensing capability operators (ESCs) that monitor the spectrum occupancy to determine when the incumbents are absent. Two key aspects of this framework that impact how spectrum access firms (SAs) using this spectrum may compete are the differences in information provided by different ESCs and how different firms bundle their services using the licensed and unlicensed band. We show that if the SAs tend to use the unlicensed band more, they will prefer to obtain information from different ESCs. On the other hand, if one of the SAs uses the licensed band more, both the SAs tend to obtain information from the same ESC. If both the SAs tend to differ more in accessing the unlicensed bandwidth, they tend to obtain information from the same ESC more. Our analysis reveals that regulation is required if there is a single ESC, as the unlicensed spectrum may be unused if the user's valuation is high.