Physical Layer Security improvement of wireless sensor networks in the presence of an untrusted user

Abstract

In this project, Physical Layer Security (PHY{Security) is increasingly being adopted to guarantee secure wireless communications because it takes advantage of the imperfections of wireless channels such as fading, noise and interference to secure communication between the Base station and legitimate nodesthe.A secure transmission in wireless sensor networks consisting of one multiple-antenna base station, multiple single antenna legitimate nodes, one single-antenna eavesdropper and one multiple-antenna cooperative jammer is investigated. In order to maximize the secrecy performance of the network, the Selection Combining scheme is exploited over the legitimate nodes. In the meantime, the transmit antenna selection is employed at the BS and cooperative jamming is adopted at the jammer node, aiming at reducing scheduling complexity at the BS and achieving satisfactory secrecy performance. Furthermore, depending on whether the jammer node has the channel state information of both the main and wiretap channels, it explores a zero-forcing beamforming (ZFB) scheme to confuse the eavesdropper while avoiding interference to the legitimate nodes. Subsequently, a novel hybrid secure transmission scheme is proposed, denoted as TAS-SC-ZFB, for WSNs. The exact closed-form expressions for the secrecy outage probability and the e ective secrecy throughput for this scheme are derived to characterize the secrecy performance. Using these closed-form expressions, the optimal power allocation factor between the BS and jammer is determined to minimize the secrecy outage probability, while the optimal secrecy rate is decided to maximize the e ective secrecy throughput for this scheme. Numerical results are provided to the validate the theoretical analysis and show the impact of key system parameters on the secrecy performance.