Relay selection for secure backscatter wireless communications

The growing demand for anti-eavesdropping security has inspired the study of physical-layer security in wireless communications. Relay-assisted secure backscatter communications are considered. The secrecy rate of the system is studied and the condition for a positive secrecy rate is analysed. The optimal relay selection algorithm and a suboptimal selection algorithm with much lower computational complexity are proposed. Simulation results show that the designed selection algorithms significantly outperform random selection in terms of average secrecy rate. The suboptimal selection approximately achieves the same average secrecy rate as the optimal selection.