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Title: Enhancing Physical-Layer Security in Wireless Powered Communication Networks
Keywords: Physical-layer security;wireless energy harvesting;cooperative jamming full-duplex;inperfect channel state information;smart grid
Publisher: University of Sydney;Faculty of Engineering and IT;School of Electrical and Information Engineering
Description: In modern society, the communications sector is a critical enabler of economic and social activity. Despite the benefit of the improved ubiquitousness, the rapid diffusion of communications technologies is driving one to question the security of communications networks and systems. It is this situation which has motivated the research and development work to be reported in this thesis. Especially, this thesis consists of two parts: The first part focuses on our main research under the umbrella of physical-layer security (PLS), and the second part presents our work on security and data management in Smart Grid communication networks (SGCNs). Security technologies embedded at the physical layer of the communication systems can provide additional countermeasure against the inherent interception threat associated with a wireless transmission medium. Unlike traditional cryptographic solutions, which usually handle security at the network and application layer, the PLS techniques exploit the randomness that is intrinsic to the physical communication channel. Specifically, the first part of this thesis addresses the problem of defeating passive eavesdroppers in wireless-powered communication networks (WPCNs). The primary concern is to develop and analyze secure transmission protocols based on PLS and radio frequency energy harvesting techniques in WPCNs. This thesis starts with investigating the problem of secure transmission between a wireless-powered transmitter and a receiver in the presence of multiple eavesdroppers. To counteract eavesdropping, a transmission protocol named accumulate-then-transmit (ATT) is proposed. Specifically, the proposed protocol employs a multi-antenna power beacon (PB) to assist the transmitter with secure transmission. First, the PB transfers wireless power to charge the transmitter's battery. After accumulating enough energy, the transmitter sends confidential information to the receiver, and simultaneously, the PB emits jamming signals (i.e., artificial noise) to interfere with the eavesdroppers. A key element of the protocol is the perfect channel state information (CSI), with which the jamming signals can be deliberately designed to avoid disturbing the intended receiver. Based on the assumption that the eavesdroppers do not collude, the secrecy performance of the proposed protocol is evaluated in terms of secrecy outage probability and secrecy throughput. This study reveals that cooperative jamming (CJ) is a critical enabler of physical-layer security in WPCNs. After investigating the use of a multi-antenna PB with perfect CSI, this thesis exploits the employment of a wireless-powered full-duplex (FD) jammer to enhance the secrecy in the presence of CSI errors. Noteworthy, due to imperfect CSI, the jamming signals transmitted by the jammer yield undesired interference at the receiver. This study analyzes the impact of channel estimation error on the secrecy performance. Besides, due to the FD capability, the jammer is able to perform simultaneous jamming and energy harvesting. It hence makes the energy storage of the jammer experience concurrent charging and discharging. A hybrid energy storage system with finite capacity is adopted, and its long-term stationary distribution of the energy state is characterized through a finite-state Markov Chain. The secrecy performance of the proposed accumulate-and-jam (AnJ) protocol is evaluated to reveal its merits. Moreover, an alternative energy storage model with infinite capacity and the use of a wireless-powered half-duplex (HD) jammer are also exploited to serve as benchmarks. In the second part of the thesis, security and data management issues are investigated in SGCNs. Due to the integrations of communications and information technologies with the power system, data security and management play a crucial role in the Smart Grid. First, the problem of the unauthorized real-time pricing (RTP) information redistribution between advanced metering infrastructure (AMI) participants and nonparticipants is addressed via an evolutionary game model. The objective is to find the optimal AMI subscription price associated with the maximal proportion of participating consumers. Second, a voluntary real-time incentive scheme is proposed to promote the participation of electricity consumers in reporting their power demand. Simulation results demonstrate that the proposed voluntary scheme can achieve satisfactory social welfare as compared with compulsory demand upload schemes. Finally, time-varying attacks in the SGCNs are studied, and a time-correlated attacker-defender model is developed and analyzed to ensure attack detection while maintaining low defense expense.;Access is restricted to staff and students of the University of Sydney . UniKey credentials are required. Non university access may be obtained by visiting the University of Sydney Library.
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Type Of Material: OTHER
Appears in Collections:Postgraduate Theses

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