Security is a critical concern in shared spectrum environments, where attacks can degrade service and influence market interactions between competing service providers (SPs). This work analyzes SPs’ strategic security investments against revenue-minimizing attackers in licensed shared bands. We model investment decisions under simultaneous and sequential competition, characterizing the existence and structure of equilibrium outcomes. Our results show that investment cost level, attack uncertainty, and risk aversion significantly impact market stability. Uncertain attacks and over-investment can shape equilibrium strategies and increase losses.
