Game Theoretic Analysis of Citizens Broadband Radio Service

The Citizens Broadband Radio Service (CBRS) is a spectrum sharing framework on the 3.5 GHz tier with three priority tiers: the incumbents, priority commercial users (PAL), and general commercial users (GAA). Thus, commercial users compete for resources within the second and third priority tiers. The interaction between commercial providers and customers is complicated by the presence of the incumbents, who impact the availability of spectrum but bypass the market entirely. In particular, PAL customers are themselves subject to preemption even with the priority purchase. In this paper, we propose a game-theoretic framework to shed light into the equilibrium outcomes and the impact of the incumbents into these. We determine that there exist several possible equilibrium regions, including one with a unique mixed equilibrium which is stable in the evolutionary stable strategy sense, and others featuring unstable mixed equilibria and stable pure equilibria. We show that for fixed parameters, the maximum possible revenue a provider can obtain is associated with a stable equilibrium and is thus guaranteed. However, changes in incumbent behavior can result in phase changes which have a sizable impact on the maximum potential revenue.