Achieving Secure Communication in CRN with Malicious Energy Harvester Using Game Theory

In this paper, an underlay based cognitive radio network (CRN) consisting of a secondary base station (SBS), a secondary receiver (SR), an energy harvesting node (EHN), and a primary transmitter-receiver (PT-PR) pair, is considered. The EHN is assumed to have a power splitter (PS) at the receiver to decode information and harvest energy simultaneously from the SBS transmission, thus reducing the secrecy capacity of SBS. Since both the SBS and the malicious EHN are selfish with conflicting interests, we model the interaction between them as a non-cooperative Stackelberg game. The objective of the SBS is to maximize the secrecy rate and minimize its interference at the PR, whereas the EHN aims at maximizing both the energy it can harvest and the information it can decode from the received SBS signal. The existence of a unique equilibrium point is proved through mathematical analysis. Further, a distributed algorithm is proposed, following which the players will attain the equilibrium of the game as predicted by analytical results. Analytical and simulation results demonstrate that both SBS and EHN can achieve their optimal utilities by adopting the equilibrium strategy.