Physical-Layer Security for Energy-Harvesting Multiuser Systems Under Hardware Impairments and Channel Estimation Errors

This paper considers a typical system composed of multiple energy-constraint users, a destination, and a passive eavesdropper who may intercept confidential information. Each communication time frame is divided into two phases. The first phase is that the energy-constraint users harvest energy from a power beacon. To safeguard the legitimate transmissions, we propose two multiuser scheduling schemes, namely selection combining scheduling (SCS) scheme and switch-and-examine combining scheduling with post-selection (SECSPS) scheme, which only depend on the channel state information of main links spanning from energy-constraint users to the destination. We derive the closed-form expressions of outage probability, intercept probability, and effective secrecy throughput under hardware impairments and channel estimation errors for the SCS and SECSPS schemes. As a baseline, we exploit the system performance for the round-robin scheduling (RRS) scheme. The numerical results verify the correctness of our derivations, demonstrating that the proposed SCS scheme achieves the best performance while the RRS scheme performs the worst in terms of system performance. Furthermore, our proposed SECSPS scheme consumes less computation overhead than the SCS scheme if a suitable threshold is adopted and it requires more computation overhead than the RRS scheme regardless of the threshold.