Secure Communication with Energy-Harvesting Buffer-Aided Jammer

Information security and self-sustainability are crucial to resource-limited wireless networks. In this paper, we assess the secrecy performance of the legitimate link without having eavesdropper's channel state information (CSI) while considering an energy harvesting (EH) jammer with finite and infinite energy buffer sizes. The EH jammer utilizes accumulated energy from its buffer and transmits artificial noise (AN) to ensure secure communication. To manage the uncertainty in harvested energy and consumption, we analyze on-off (OO) jamming and always-on (AO) jamming schemes. The analytical expressions are obtained for secrecy outage probability (SOP). This analysis models the energy arrival and departure process by a discrete-time continuous-state Markov chain to eliminate the computational complexity and inaccuracy of a discrete-state Markov chain. Both the schemes are compared using SOP and secure throughput. This analysis shows the adequacy of a finite buffer for an EH jammer and also the fact that the availability of jamming power has a more pronounced effect on SOP as compared to a larger number of antennas at the jammer.