In this work, we study the secrecy performance of a reconfigurable intelligent surfaces (RIS)-aided wireless communication system in the presence of an eavesdropping user. Specifically, we assume that the RIS is placed between the source and the legitimate user to create a smart environment and used to improve the link security. In particular, analytical results for the secrecy outage probability (SOP) is derived. We also provide an asymptotic analysis to investigate the effect of the main parameters on the secrecy performance of our proposed system, such as the number of the reflectors in the RIS and the average signal-to-noise ratios. Finally, we verify our analytical results via simulations. Results show the positive effect of utilizing the RIS for enhancing wireless systems secrecy performance.

No abstract

In this paper, we consider the secrecy outage probability (SOP) of a cooperative non-orthogonal multiple access (NOMA) vehicular communication (VC) system, where the relay is working in either halfduplex (HD) or full-duplex (FD) mode. We assume that all these links experience Nakagami-m fading. Some closed-form analytical expressions for the SOP performance of the FD/HD cooperative NOMA-VC system are derived. Results show that the secrecy performance of FD-based NOMA-VC system is superior than HD-based NOMA-VC in the low signal noise ratio (SNR) region, and can be further improved by reducing the self-interference caused by FD technique. Finally, the validity of this analytical expressions is verified by using simulation. The simulation results show that the simulation curve can be fit well with our analytical results. INDEX TERMS Physical layer security, non-orthogonal multiple access, cooperative communications, full/half duplex relaying, vehicular communication. PENG ZHU was born in Yueyang, Hunan, China, in 1990. He received the Ph.D. degree in space physics from Wuhan University. Since 2016, he has been a Lecturer with HNIST. His major research interests include signal processing and communication techniques. XINZHONG LIU was born in 1978. He received the Ph.D. degree. His main research interests include software reliability analysis, computer communication security, and heterogeneous parallel computing.

No abstract

With the development of the unmanned aerial vehicle (UAV), UAV is widely used in various fields, such as Industrial IoT. Usually, the communication between UAV and the ground node is the line-of-sight (LoS) transmission. However, the performance of the UAV wireless communication system degrades greatly as the LoS links are prone to deteriorate in some complex communication scenarios. Fortunately, the quality of the communication link can be improved effectively by placing reconfigurable intelligent surfaces (RISs) into the ground nodes and UAV. Motivated by this, by optimizing the RIS passive beamforming, the ground user association, the UAV trajectory and transmit power synthetically, in this paper, we propose a secure RISassisted UAV wireless communication system based on multiple ground users to maximize the minimum average security rate among ground users. Also, we conduct an efficient algorithm based on the block coordinate descent (BCD) and successive convex approximation (SCA) methods to solution the no-convex optimization problem. Compared with the benchmark algorithm, the simulation results show that the proposed algorithm can improve the security performance of the RIS-assisted UAV wireless communication system effectively.