Coalitional game based joint beamforming and power control for physical layer security enhancement in cognitive IoT networks

In this paper, the physical layer secure transmission in multi-antenna multi-user cognitive internet-of-thing (IoT) network is investigated, where the coalitional game based joint beamforming and power control scheme is proposed to improve the achievable security of cognitive IoT devices. Specifically, the secondary network consisting of a muti-antenna secondary transmitter, multiple secondary users (SUs), is allowed to access the licensed spectrum resource of primary user (PU) with underlay approach in the presence of an unauthorized eavesdropper. Based on the Merge-Split-Rule, coalitional game is formulated among distributed secondary users with cooperative receive beamforming. Then, an alternative optimization method is used to obtain the optimized beamforming and power allocation schemes by applying the up-downlink duality. The simulation results demonstrate the effectiveness of our proposed scheme in improving the SU's secrecy rate and system utility while guaranteeing PU's interference threshold.