Secure transmission solutions in energy harvesting enabled cooperative cognitive radio networks

In this paper, we investigate secure communications in energy harvesting enabled cooperative cognitive radio networks (CCRNs). In such CCRNs, a pair of primary users (PUs) can only communicate with each other through a relay. To protect data transmission between PUs, we propose a cooperative jamming strategy with energy harvesting technology. In the first phase, a PU as the source (PU-S) broadcasts signals, while another PU as the destination (PU-D) sends artificial noise (AN) and all secondary uses (SUs) harvest energy from the received mixed signals. In the second phase, one SU selected as a relay (SU-R) uses its harvested energy to forward PU's signals, while another SU selected as a jammer (SU-J) employs its harvested energy to send AN. According to this, we formulate a non-convex problem aiming to improve the secrecy rate of PUs and divide this problem into three optimization subproblems. Finally we provide a feasible joint solution by a two-tiered iterative algorithm. Numerical results demonstrate the secrecy performance of our proposed jamming strategy.