Secrecy Throughput Maximization for Full-Duplex Wireless Powered IoT Networks under Fairness Constraints

In this paper, we study the secrecy throughput of a full-duplex wireless powered communication network (WPCN) for internet of things (IoT). The WPCN consists of a full-duplex multi-antenna base station (BS) and a number of sensor nodes. The BS transmits energy all the time, and each node harvests energy prior to its transmission time slot. The nodes sequentially transmit their confidential information to the BS, and the other nodes are considered as potential eavesdroppers. We first formulate the sum secrecy throughput optimization problem of all the nodes. The optimization variables are the duration of the time slots and the BS beamforming vectors in different time slots. The problem is shown to be non-convex. To tackle the problem, we propose a suboptimal two stage approach, referred to as sum secrecy throughput maximization (SSTM). In the first stage, the BS focuses its beamforming to blind the potential eavesdroppers (other nodes) during information transmission time slots. Then, the optimal beamforming vector in the initial non-information transmission time slot and the optimal time slots are derived. We then consider fairness among the nodes and propose max-min fair (MMF) and proportional fair (PLF) algorithms. The MMF algorithm maximizes the minimum secrecy throughput of the nodes, while the PLF tries to achieve a good trade-off between the sum secrecy throughput and fairness among the nodes. Through numerical simulations, we first demonstrate the superior performance of the SSTM to uniform time slotting and beamforming in different settings. Then, we show the effectiveness of the proposed fair algorithms

Research Issues, Challenges, and Opportunities of Wireless Power Transfer-Aided Full-Duplex Relay Systems

We present a comprehensive review for wireless power transfer (WPT)-aided full-duplex (FD) relay systems. Two critical challenges in implementing WPT-aided FD relay systems are presented, that is, pseudo FD realization and high power consumption. Existing time-splitting or power-splitting structure based-WPT-aided FD relay systems can only realize FD operation in one of the time slots or only forward part of the received signal to the destination, belonging to pseudo FD realization. Besides, self-interference is treated as noise and self-interference cancellation (SIC) operation incurs high power consumption at the FD relay node. To this end, a promising solution is outlined to address the two challenges, which realizes consecutive FD realization at all times and forwards all the desired signal to the destination for decoding. Also, active SIC, that is, analog/digital cancellation, is not required by the proposed solution, which effectively reduces the circuit complexity and releases high power consumption at the FD relay node. Specific classifications and performance metrics of WPT-aided FD relay systems are summarized. Some future research is also envisaged for WPT-aided FD systems

Transceiver design for wireless energy harvesting cooperative networks

In this thesis, the RF energy harvesting technique is studied in the cooperative wireless network, and different optimization studies are investigated. First, an energy-efficient optimization is considered in the cooperative system with the time switching relaying and power splitting relaying protocols. Then, a security issue in the cooperative network with energy harvesting is proposed, in which the optimization problem is designed to maximize the secrecy rate. We also consider the application of energy harvesting in the full-duplex relaying network with a self-energy recycling protocol. Finally, the energy harvesting is studied in the full-duplex cooperative cognitive radio network. The system performance of all studies is verified in the thesis with MATLAB simulation results

도청자가 존재하는 전이중 무선전력통신에서 에너지 빔 형성

학위논문 (석사)-- 서울대학교 대학원 공과대학 전기·정보공학부, 2017. 8. 이재홍.To improve spectrum utilization, full duplex (FD) communication technique is applied to wireless powered communication (WPC). The cochannel interference from energy transmission reduces achievable rate of information transmission. However, when an eavesdropper tries to intercept the information in the FD WPC systems, the energy signal from the power beacon acts as a jamming signal to the eavesdropper. Hence, the secrecy rate of the system is not always degraded by the energy transmission. In this thesis, to control the energy signal transmitted to the source and eavesdropper, we propose an optimal beamforming scheme for secure communication in a FD WPC system consists of a multi-antenna power beacon, a source, a destination, and an eavesdropper. By using the beamforming scheme, the power beacon transmits an energy signal to a source which acts as a jamming signal to an eavesdropper and the source transmits an information signal by using harvested energy. We consider a scenario that the channel state information of eavesdropper is imperfect. We formulate an optimization problem to find an optimal beamforming for maximizing worst-case secrecy rate assuming that channel state information of the wiretap channel is imperfect. Also, we propose an algorithm to solve the problem. Simulation results show the secrecy performance of FD WPC system with the proposed beamforming scheme.Chapter 1 Introduction 1 Chapter 2 System Model 5 2.1 Received SINR and Secrecy Rate 7 2.2 Worst-Case Secrecy Rate 10 Chapter 3 Maximization of Worst-Case Secrecy Rate 13 Chapter 4 Proposed Energy Beamforming 17 Chapter 5 Simulation Results 26 Chapter 6 Conclusion 38Maste