Secrecy Energy Efficiency for Distributed-IRSs Assisted Uplink Networks

In this correspondence, we aim at achieving the energy-efficient secrecy transmission for an uplink network assisted by distributed intelligent reflecting surfaces (D-IRSs). The secrecy energy efficiency (SEE) maximization problem is investigated through jointly optimizing the discrete reflecting phase shifts, the transmit power, and the IRS switching status. To handle this non-convex problem, we decompose it into three subproblems, and then the majorization-minimization based algorithm, the Dinkelbach method and the Lagrangian dual method are adopted to obtain the solutions of reflecting phase shifts, transmit power and IRS switching status, respectively. The subproblems are alternatively optimized based on the iterative algorithm. Simulation results show that the proposed scheme can significantly improve the SEE compared to the centralized IRS, especially when the eavesdropping channel is stronger.