Generalized Non-linear Energy Harvesting Protocol for Enhancing Security of AF Multi-Antenna Relaying Systems

Abstract

In this paper, we proposed a generalized energy harvesting (GEH) protocol and utilized a non-linear energy harvesting (EH) model for AF Multi-Antenna Relaying Systems. In particular, the GEH protocol is a optimal EH protocol based on time switching relaying (TSR) and power splitting relaying (PSR) protocols. The whole communication process contains two phases. In phase I, the source transmits certain signal to the relay, meanwhile the destination transmits an artificial noise (AN) to interfere with the passive eavesdropper. The relay harvests energy from the two nodes. In phase II, the relay node processes the two different received signals, which are transmitted from the source and destination. Then the relay amplify-and-forward them by utilizing the harvested energy. To accurately reflect the non-linear nature of the practical EH circuit of GEH-based systems, we apply a special kind of quasi-concave function named logistic (sigmoidal) function to model the input-output characteristic. We also derive a new analytical formula for proposed generalized non-linear energy harvesting protocol on ergodic secrecy capacity. The effect of the number of relay antennas N, the source transmitted power Pthe destination transmitted power Pd on ergodic secrecy capacity are investigated. The simulation results show that as N, P s , Pd increase, the ergodic secrecy capacity of GEH system increases accordingly. Moreover, the GEH protocol can provide higher non-linear ergodic secrecy capacity than time switching relaying (TSR) protocol and almost perform as better as power splitting relaying (PSR) protocol.