Generalised Switching Protocol of Energy Harvesting for Enhancing the Security of AF Multi‐antenna Relaying Systems

In this study, the authors propose a generalised switching protocol (GSP) for increasing the flexibility of energy harvesting (EH) protocol and enhancing the security of amplify-and-forward (AF) multi-antenna relaying system. The proposed GSP-based relaying [generalised switching relaying (GSR)] system is established with target node assisted interference and EH technologies. In phase I, while the source transmits certain signal to the relay, the destination transmits an artificial noise to interfere the passive eavesdropper. In this phase, the relay harvests energy from the two nodes. In phase II, the relay node processes the two different received signals, which are from the source and destination, then AF them by utilising the harvested energy. The authors also derive a new analytical formula for the proposed protocol on ergodic secrecy capacity. The effect of the number of relay antennas N, the source transmitted power P-s, the destination transmitted power P-d and EH efficiency factors eta(t) and eta(p) on ergodic secrecy capacity are investigated. The simulation results show that as N, P-s, P-d, eta(t) and eta(p) increase, the ergodic secrecy capacity of GSR system increases accordingly. Moreover, the GSR protocol can provide higher ergodic secrecy capacity than both time switching relaying and power splitting relaying protocols.