Cognitive radio is a promising paradigm for dramatically increasing the utilization of wireless spectrum to support the continuing exponential growth in wireless traffic. Research on cognitive networks has mainly focused on sensing of spectrum opportunities and managing radio resources such that the primary users' quality of service is not compromised. Much less attention has been paid to the coexistence of secondary users, which may be associated with different cognitive networks and seek to operate in the same frequency bands. Effective coexistence of such users is essential for the success of future cognitive networks, and is the main objective of this project. In addition, the particularly open nature of cognitive radio raises significant new issues for the security and privacy of the transmitted data, as well as new opportunities for malicious behavior among cognitive or outside entities. The project addresses all of these issues in a holistic framework.
Coexistence requires effective allocation of radio resources in time, frequency, and space among multiple cognitive secondary users, while respecting primary interference constraints. The investigators are developing theoretical bounds for such radio resource management schemes and designing low-overhead distributed algorithms, which account for the incentives of competing secondary service providers as well as the stronger security and privacy measures needed in a cognitive environment. Information-theoretic physical-layer security techniques are being utilized to develop provably secure paradigms for secondary cognitive users and game-theoretic models are being adapted to study the robustness of these networks to various jamming attacks and other malicious behavior.
