Securing Small Cell Networks Under Interference Constraint: A Quasi-Variational Inequality Approach

Abstract

Small cell networks are envisioned as one of the critical enabling technologies for the next-generation wireless systems. However, due to the limited capability of small cell base stations as compared with the macro-cell base stations, the secure wireless communication faces significant challenges. Towards this issue, we target at enhancing the wireless security for small cell networks by employing the physical layer security techniques. Specifically, we maximize the secrecy rate for each individual small cell in a distributed manner, while protecting the transmissions in the macro-cell by imposing the aggregate interference constraint over the small cell transmissions. The distributed secrecy competition is formulated as a generalized Nash equilibrium problem, for which we adopt its equivalence in the form of the quasi-variational inequality to analyze the existence and uniqueness of the Nash equilibrium. Furthermore, we tackle the interference constraint as the penalty over the secrecy rate of the small cells and introduce the Nash equilibrium problem formulation. Then, the distributed algorithm is proposed based on the best-response strategy to solve for the Nash equilibrium of the secrecy competition game. Finally, simulation results are provided to corroborate our theoretical findings.