This paper studies the secrecy performance of an intelligent reflecting surface (IRS)-aided indoor wireless communication where the IRS is capable of adjusting the direction and phase shift of reflected signal on its surface and assists a source to communicate with an authenticated user in the presence of several unauthenticated users, which can be potential eavesdroppers. The goal of this paper is to design a tile-allocation-and-phase-shift-adjustment (TAaPSA) strategy for the IRS to optimize the average secrecy rate (ASR); moreover, the respective secrecy outage probability (SOP) for this TAaPSA is evaluated. To achieve this goal, the ray model and the Rice distribution are adopted to describe the propagation of the IRS’s reflected signals and the fading process, respectively. Closed-form analytical expressions for the ASR and the SOP are derived. Using these analytical results, a genetic algorithm (GA) is utilized to find an optimal TAaPSA strategy for the IRS. The accuracy of the analytical results and the improvement in ASR using GA-based TAaPSA strategy are verified by simulation results.

Intelligent reflecting surface has recently emerged as a cost-effective solution to overcome the deep fading and uncontrollable wireless environment. This leads to a need for studies on the wireless channels of IRS-aided wireless communication (IRSaWC). This paper proposes a novel channel modelling method for the IRSaWC by exploiting the physics characteristic of the electromagnetic (EM) field on the IRS and the modified Saleh-Valenzuela (SV) model. Firstly, the reflection on a single reflecting tile (RT) of the IRS is investigated in the presence of a misalignment between the RT’s configured incident angle and the actual incident angle, and the RT’s phase distortion. Then, the path loss and phase shift models for the reflected field are developed. Extending our study to the multiple-RT scenario and utilizing the modified SV model, the channel characteristic for the IRSaWC is determined. Our analysis shows that the information signal at the receiver experiences a Rice fading with controllable parameters. Theoretical results for the path loss, the channel’s parameters, and the received distortion power are derived; moreover, an approximate distribution for the combined signal-to-noise ratio (SNR) for IRS-aided multiple-antenna wireless systems (IRSaMAWSs) has been investigated with the aim of conducting further studies on theoretical performance for IRSaMAWSs.

In this paper, we study the impact of residual transmit radio-frequency impairments (RTRIs) on a dual-hop energy-harvesting system in which a source and a destination both having multiple antennas communicate to each other with the help of single-antenna amplify-and-forward (AF) relays. The source and destination employ maximum ratio transmission (MRT) and maximal ratio combining (MRC), respectively, to exploit the benefits of using multiple antennas. To simplify the system complexity, we propose two partial relay selection (PRS) schemes (RSSs) that maximise the combined channel gains of the first hop (PRS-1 scheme) and the second hop (PRS-2 scheme), respectively. Both time-switching relaying (TSR) and power-splitting relaying (PSR) protocols are examined. In order to evaluate the system performance, the analytical expressions for outage probability and ergodic capacity are derived, and then the throughput expressions for delay-limited and delay-tolerant transmission modes are formulated. The analytical results are validated by Monte Carlo simulations. Our results show that: (1) The impact of RTRI can be significantly reduced by increasing the number of antennas and relays. (2) The PRS-1 scheme outperforms the PRS-2 scheme. (3) In the delay-limited mode, the TSR protocol performs better than the PSR protocol at high impairment levels, whereas in the delay-tolerant mode, the throughput of the PSR protocol is superior to that of the TSR protocol.