Cooperative Jamming-Aided Secure Communication in Wireless Powered Sensor Networks

Cooperative jamming (CJ) is a promising technique for enhancing the physical-layer security in wireless powered sensor networks. The secrecy performance of CJ-aided wireless powered sensor networks is affected by three issues including disguised eavesdropper as cooperative node, estimation error of the channel between sink node and each sensor node, and distance-related limitation on the transmit power of cooperative nodes. To address the above issues, this paper proposes a CJ-aided secure communication scheme for wireless powered sensor networks with disguised eavesdropper and imperfect channel estimation. Since each cooperative node could be the disguised eavesdropper, the proposed scheme incorporates all possible cases of the eavesdropper disguising itself as unfixed cooperative jamming node. The maximization of secrecy rate over all possible cases is formulated for designing secrecy optimization problem. The imperfect channel estimation and distance-related jamming power limitation are both integrated as constraints into the secrecy rate maximization problem. Since the original optimization problem is complex and non-convex, a two-level optimization algorithm is proposed to solve it. Simulation results show that the proposed scheme achieves significant secrecy rate improvement over typical existing schemes.