Browsing by Author "Wang, Hui-Ming"
Now showing 1 - 4 of 4
- Results Per Page
- Sort Options
Item Cooperative Secure Transmission by Exploiting Social Ties in Random Networks(IEEE Transactions on Communications, 3/30/2018) Wang, Hui-Ming; Xu, Yiming; Huang, Ke-Wen; Han, Zhu; Tsiftsis, Theodoros A.Social awareness and social ties are becoming increasingly popular with emerging mobile and handheld devices. Social trust degree describing the strength of the social ties has drawn lots of research interests in many fields in wireless communications, such as resource sharing, cooperative communication, and so on. In this paper, we propose a social ties based hybrid cooperative beamforming and jamming scheme to secure wireless transmissions under a stochastic geometry framework, where the friendly nodes are categorized into relays and jammers according to their locations and social trust degrees with the source node. Connection outage probability (COP) and secrecy outage probability (SOP) of such a scheme in a random network have been analyzed. To facilitate a more convenient performance evaluation, we propose a double Gamma ratio approach through the Gamma approximation method. Based on this, the COP and SOP are tractably obtained in closed-forms. We further consider the SOP in the presence of Poisson point process distributed eavesdroppers and derive an upper bound. The simulation results verify our theoretical findings, and validate that the social trust degree has dramatic influences on the security performance in the networks.Item Physical Layer Security in MIMO Backscatter Wireless Systems(IEEE Transactions on Wireless Communications, 8/31/2016) Yang, Qian; Wang, Hui-Ming; Zhang, Yi; Han, ZhuBackscatter wireless communication is an emerging technique widely used in low-cost and low-power wireless systems, especially in passive radio frequency identification (RFID) systems. Recently, the requirement of high data rates, data reliability, and security drives the development of RFID systems, which motivates our investigation on the physical layer security of a multiple-input multiple-output (MIMO) RFID system. In this paper, we propose a noise-injection precoding strategy to safeguard the system security with the resource-constrained nature of the backscatter system taken into consideration. We first consider a multi-antenna RFID tag case and investigate the secrecy rate maximization (SRM) problem by jointly optimizing the energy supply power and the precoding matrix of the injected artificial noise at the RFID reader. We exploit the alternating optimization method and the sequential parametric convex approximation method, respectively, to tackle the non-convex SRM problem and show an interesting fact that the two methods are actually equivalent for our SRM problem with the convergence of a Karush-Kuhn-Tucker point. To facilitate the practical implementation for resource-constrained RFID devices, we propose a fast algorithm based on projected gradient. We also consider a single-antenna RFID tag case and develop a low-complexity algorithm, which yields the global optimal solution. Simulation results show the superiority of our proposed algorithms in terms of the secrecy rate and computational complexity.Item Physical Layer Security in Wireless Ad Hoc Networks Under A Hybrid Full-/Half-Duplex Receiver Deployment Strategy(IEEE Transactions on Wireless Communications, 3/29/2017) Zheng, Tong-Xing; Wang, Hui-Ming; Yuan, Jinhong; Han, Zhu; Lee, Moon HoThis paper studies physical layer security in a wireless ad hoc network with numerous legitimate transmitter-receiver pairs and eavesdroppers. A hybrid full-duplex (FD)/half-duplex receiver deployment strategy is proposed to secure legitimate transmissions, by letting a fraction of legitimate receivers work in the FD mode sending jamming signals to confuse eavesdroppers upon their information receptions, and letting the other receivers work in the half-duplex mode just receiving their desired signals. The objective of this paper is to choose properly the fraction of FD receivers for achieving the optimal network security performance. Both accurate expressions and tractable approximations for the connection outage probability and the secrecy outage probability of an arbitrary legitimate link are derived, based on which the area secure link number, network-wide secrecy throughput, and network-wide secrecy energy efficiency are optimized, respectively. Various insights into the optimal fraction are further developed, and its closed-form expressions are also derived under perfect self-interference cancellation or in a dense network. It is concluded that the fraction of FD receivers triggers a non-trivial tradeoff between reliability and secrecy, and the proposed strategy can significantly enhance the network security performance.Item Wireless Powered Asynchronous Backscatter Networks With Sporadic Short Packets: Performance Analysis and Optimization(IEEE Internet of Things Journal, 1/31/2018) Yang, Qian; Wang, Hui-Ming; Zheng, Tong-Xing; Han, Zhu; Lee, Moon HoIn the fifth generation era, the pervasive applications of Internet of Things and massive machine-type communications have initiated increasing research interests on the backscatter wireless powered communication (B-WPC) technique due to its ultrahigh energy efficiency and low cost. The ubiquitous B-WPC network is characterized by nodes with dynamic spatial positions and sporadic short packets, of which the performance has not been fully investigated. In this paper, we give a comprehensive analysis of a multiantenna B-WPC network with sporadic short packets under a stochastic geometry framework. By exploiting a time-space Poisson point process model, the behavior of the network is well captured in a decentralized and asynchronous transmission way. We then analyze the energy and information outage performance in the energy harvest and backscatter modulation phases of the backscatter network, respectively. The optimal transmission slot length and division are obtained by maximizing the network-wide spatial throughput. Moreover, we find an interesting result that there exists the optimal tradeoff between the durations of the energy harvest and backscatter modulation phases for spatial throughput maximization. Numerical results are demonstrated to verify our analytical findings and show that this tradeoff region gets shrunk when the outage constraints become more stringent.