Considering the important applications of wireless sensor networks in target monitoring, it has received attention in the civil and military fields. For the problem that the working nodes die early, the network energy consumption is large, and the node energy distribution is uneven, especially the impact of the monitored target on the network performance, this study is based on the traditional low-energy adaptive clustering hierarchy (LEACH) and target location constraint, an improved LEACH target location constraint (LEACH-TLC) algorithm is proposed. First, under the premise of monitoring accuracy, this study constructs a network monitoring performance parameter model. Second, the wake-up/dormant threshold of the network node is obtained based on the network performance parameter model, and the network node dormant strategy is constructed utilising the threshold, and then the working node set is constructed. Finally, based on the proposed network energy uniform mechanism, combined with the distance factor between the node and target/base station, a new cluster head selection rule is proposed. The simulation results show that the LEACH-TLC algorithm can decrease the number of working nodes, reduce network energy consumption, uniform node energy consumption distribution, and prolong network lifetime.
Physical layer security of non-orthogonal multiple access (NOMA) system which uses simultaneous wireless information and power transfer (SWIPT) technique is deeply dicussed in this paper. Generally, eavesdropper in the downlink of NOMA system may use successive interference cancellation technology (SIC) to obtain the secrecy information of receiver. To tackle this problem, we propose a physical layer security scheme to minimize the transmit power of the base station (BS) while the secrecy rates of receivers are guaranteed. Moreover, semidefinite relaxation (SDR) method and successive convex approximation (SCA) technique are combined to solve above non-convex problem. Simulation results show that in comparison with other methods, our method can effectively reduce the transmit power of the BS.
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