Intelligent Reflecting Research Articles

Optimum Beamforming and Grating-Lobe Mitigation for Intelligent Reflecting Surfaces

Optimum Beamforming and Grating-Lobe Mitigation for Intelligent Reflecting Surfaces

Flexible printing paper-based reconfigurable smart metasurfaces

In the rapidly evolving wireless communication landscape, achieving full-dimensional coverage poses a gamut of challenges such as intricacy, high hardware costs and energy consumption. In addressing these issues, reconfigurable metasurfaces are being considered as a potential solution. However, traditional methods of producing reconfigurable metasurfaces via printed circuit board (PCB) technologies possess limitations such as high cost and extended production cycles. Particularly, in the context of large-scale communication scenarios, reconfigurable metasurfaces can also present high energy consumption issues. Therefore, this paper proposes a novel type of intelligent reflection surface (IRS) characterized by lower production costs, reduced energy consumption, enhanced flexibility, ease of manufacture, and superior electromagnetic wave modulation capabilities. The proposed reconfigurable smart metasurface is a paper-based metasurface printed with conductive ink, which uses conductive ink to draw base metal blocks on a flexible substrate, and uses silver-tin as a metal patch between the metal blocks, and the phase response is reconstructed with silver ink. By adjusting the distribution of these metallic patches, we tailor the phase and amplitude distributions to generate specific scattering effects. This paper presents designs of six patterns that yield single-beam and dual-beam, with experimental results aligning closely with simulated results, validating the feasibility of the proposed method. This low-power, low-cost, and efficient IRS is expected to pave a new path for advanced 5 G/6G wireless communication technologies.

Rate Optimization of Intelligent Reflecting Surface-Assisted Coal Mine Wireless Communication Systems.

This paper proposes a three-step joint rate optimization method for intelligent reflecting surface (IRS)-assisted coal mine wireless communication systems. Different from terrestrial IRS-assisted communication scenarios, in coal mines, IRSs can be installed flexibly on the tops of rectangular tunnels to address the issues of signals being blocked and interfered with by mining equipment. Therefore, it is necessary to optimize the IRS deployment position, the transmit power and IRS phase shifts to achieve the maximum effective achievable rate at user stations equipped with the proposed system. However, due to the complex channel models of coal mines, the optimization problem of IRS deployment position is non-convex. To solve this problem, two auxiliary variables along with logarithmic operations and Taylor approximation are introduced. On this basis, a three-step joint rate optimization involving the transmit power, IRS phase shifts and IRS deployment position is proposed to maximize the effective achievable rates at the user station. The simulation results show that compared with other rate optimization schemes, the effective achievable rates at the user station using the proposed joint rate optimization scheme can be improved by approximately 12.32% to 54.17% for different parameter configurations. It is also pointed out that the deployment position of the IRS can converge to the same optimal position independent of the initial deployment position. Moreover, we investigate the effects of the roughness of the tunnel walls in a coal mine on the effective achievable rates at the user station, and the simulation results indicate that the proposed three-step joint rate optimization scheme performs better in the coal mine scenario regardless of the roughness.

Intelligent Reflecting Surface-Aided Multiuser Communication: Co-Design of Transmit Diversity and Active/Passive Precoding

Intelligent Reflecting Surface-Aided Multiuser Communication: Co-Design of Transmit Diversity and Active/Passive Precoding

Bridging the Gap to 6G: Leveraging the Synergy of Standardization and Adaptability

The field of wireless network and communication technology is evolving from generation to generation from 1G to 6G as of now till expected to be deployed and used by 2030. It is to succeed in 5G and bring significant improvements in terms of connectivity, speed, and size in next-generation communication technology. 6G aims to deal with the rising need for more rapid information speed, low latency, and wider network coverage. This intelligent communication is proposed to meet these demands and enable new services and applications. This review paper highlights the key enablers and challenges involved in implementing intelligent communication beyond 5G. The paper identifies the research gaps for incorporating beyond 5G communication networks and outlines the possible 6G key objectives from a flexibility standpoint. It reviews infrastructure deployment, network densification, spectrum capacity and network energy efficiency in predecessors to 6G. This paper emphasizes the need for standardization and adaptation of research areas to revolutionize 6G wireless communication, focusing on areas like, ultra massive MIMO, Terahertz Communications, Cell-Free Communications, Intelligent Reflecting Surface, Visible Light Communication, Internet of Things, Big Data management, Artificial Intelligence, and network connectivity techniques.

Intelligent Reflecting Surface Assisted mmWave Integrated Sensing and Communication Systems

Intelligent Reflecting Surface Assisted mmWave Integrated Sensing and Communication Systems

Irregular IRS-aided SWIPT secure communication system with imperfect CSI

The performance of traditional regular Intelligent Reflecting Surface (IRS) improves as the number of IRS elements increases, but more reflecting elements lead to higher IRS power consumption and greater overhead of channel estimation. The Irregular Intelligent Reflecting Surface (IIRS) can enhance the performance of the IRS as well as boost the system performance when the number of reflecting elements is limited. However, due to the lack of radio frequency chain in IRS, it is challenging for the Base Station (BS) to gather perfect Channel State Information (CSI), especially in the presence of Eavesdroppers (Eves). Therefore, in this paper we investigate the minimum transmit power problem of IIRS-aided Simultaneous Wireless Information and Power Transfer (SWIPT) secure communication system with imperfect CSI of BS-IIRS-Eves links, which is subject to the rate outage probability constraints of the Eves, the minimum rate constraints of the Information Receivers (IRs), the energy harvesting constraints of the Energy Receivers (ERs), and the topology matrix constraints. Afterward, the formulated non-convex problem can be efficiently tackled by employing joint optimization algorithm combined with successive refinement method and adaptive topology design method. Simulation results demonstrate the effectiveness of the proposed scheme and the superiority of IIRS.

Intelligent Reflecting Surface Aided MIMO With Cascaded LoS Links: Joint Beamforming and Array Orientation Optimization

Intelligent Reflecting Surface Aided MIMO With Cascaded LoS Links: Joint Beamforming and Array Orientation Optimization

Anti-Jamming Precoding Against Disco Intelligent Reflecting Surfaces Based Fully-Passive Jamming Attacks

Anti-Jamming Precoding Against Disco Intelligent Reflecting Surfaces Based Fully-Passive Jamming Attacks

A Low-Complexity Solution for Optimizing Binary Intelligent Reflecting Surfaces towards Wireless Communication

Intelligent Reflecting Surfaces (IRSs) enable us to have a reconfigurable reflecting surface that can efficiently deflect the transmitted signal toward the receiver. The initial step in the IRS usually involves estimating the channel between a fixed transmitter and a stationary receiver. After estimating the channel, the problem of finding the most optimal IRS configuration is non-convex, and involves a huge search in the solution space. In this work, we propose a novel and customized technique which efficiently estimates the channel and configures the IRS with fixed transmit power, restricting the IRS coefficients to {1,−1}. The results from our approach are numerically compared with existing optimization techniques.The key features of the linear system model under consideration include a Reconfigurable Intelligent Surface (RIS) setup consisting of 4096 RIS elements arranged in a 64 × 64 element array; the distance from RIS to the access point measures 107 m. NLOS users are located around 40 m away from the RIS element and 100 m from the access point. The estimated variance of noise NC is 3.1614 × 10−20. The proposed algorithm provides an overall data rate of 126.89 (MBits/s) for Line of Sight and 66.093 (MBits/s) for Non Line of Sight (NLOS) wireless communication.

Highly Efficient Hybrid Reconfigurable Intelligent Surface Approach for Power Loss Reduction and Coverage Area Enhancement in 6G Networks

This paper introduces a novel efficient hybrid reconfigurable intelligent surface (RIS) approach designed to significantly reduce power loss and enhance coverage area in 6G networks. The core innovation of this approach lies in an advanced iterative algorithm introduced as the Hybrid reconfigurable intelligent surface decision-making algorithm (HRIS-DMA) that integrates precise user location data into the RIS configuration process. By dynamically adjusting RIS elements to reflect and direct signals based on real-time user positions, this method minimises signal attenuation and optimises signal propagation. The mechanism driving the performance gains includes precise beamforming and intelligent reflection, continuously refined through iterative updates. This technique ensures robust signal strength and expanded coverage, addressing the challenges of dense and diverse deployment scenarios in 6G networks. The proposed scheme’s application in 6G networks demonstrates substantial improvements in signal quality and network reliability, paving the way for enhanced user experiences and efficient communication infrastructures. This novel approach was tested using MATLAB R2023a , and its performance was evaluated using three downlink scenarios: zero to few, few to moderate, and moderate to many obstacles. The three scenarios show higher coverages than conventional simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) and base station (BS) handover. Based on the evaluation metrics, the analysis results of the novel HRIS-DMA show 70% less signal power loss, 0.17 μs less system delay, 25 dB and 12 dB channel gain compared with the conventional STAR-RIS and BS handover, respectively, and 95% improvement in the overall system’s efficiency compared to STAR-RIS and 13% compared to BS-BS handover.

Secure communication of intelligent reflecting surface-aided NOMA in massive MIMO networks

A Non-Orthogonal Multiple Access (NOMA) network, in which the base station (BS) incorporates massive Multiple-Input Multiple-Output (MIMO) technology, is considered in this paper. This research study focuses on investigating physical layer security in this network when a jammer is present, leveraging intelligent Reflecting Surface (IRS) technology. The IRS is an innovative approach strategically implemented to enhance communication quality by assisting distant users in establishing a reliable connection with the BS. Two key metrics in physical layer security are evaluated: the secrecy rate (SR) for pairs of NOMA users and the secrecy outage probability (SOP). Additionally, the impact of using a jammer is assessed by comparing the network’s performance with and without a jammer. The results indicate that by increasing in the antenna numbers, the rate of secrecy is improved, and the SOP is decreased. Moreover, as the transmit signal-to-noise ratio (SNR) increases, the SR is enhanced, but the SOP is degraded. However, the increase in the IRS element numbers results in a tendency for the SOP to rise. Furthermore, it is evident that incorporating a jammer improves the network’s performance.

Intelligent Reflecting Surface Assisted Full-Duplex Relay Systems: Deployment Design and Beamforming Optimization

Intelligent Reflecting Surface Assisted Full-Duplex Relay Systems: Deployment Design and Beamforming Optimization

Empowering 6G Non-Terrestrial Networks With Intelligent Reflection Technologies for IoT Applications

Empowering 6G Non-Terrestrial Networks With Intelligent Reflection Technologies for IoT Applications

Intelligent Reflecting Surface-Assisted Caching Cellular Network in an Urban Environment: Access Strategy and Success Probability Analysis

Intelligent Reflecting Surface-Assisted Caching Cellular Network in an Urban Environment: Access Strategy and Success Probability Analysis

Intelligent Reflecting Surface Aided Wireless Sensing: Applications and Design Issues

Intelligent Reflecting Surface Aided Wireless Sensing: Applications and Design Issues

Exploiting Active Intelligent Reflecting Surface for Wireless Powered Nonorthogonal Multiple Access

Exploiting Active Intelligent Reflecting Surface for Wireless Powered Nonorthogonal Multiple Access

Advancing reliability and efficiency of urban communication: Unmanned aerial vehicles, intelligent reflection surfaces, and deep learning techniques

Unmanned aerial vehicles (UAVs) have garnered attention for their potential to improve wireless communication networks by establishing line-of-sight (LoS) connections. However, urban environments pose challenges such as tall buildings and trees, impacting communication pathways. Intelligent reflection surfaces (IRSs) offer a solution by creating virtual LoS routes through signal reflection, enhancing reliability and coverage. This paper presents a three-dimensional dynamic channel model for UAV-assisted communication systems with IRSs. Additionally, it proposes a novel channel-tracking approach using deep learning and artificial intelligence techniques, comprising preliminary estimation with a deep neural network and continuous monitoring with a Stacked Bidirectional Long and Short-Term Memory (Bi-LSTM) model. Simulation results demonstrate faster convergence and superior performance compared to benchmarks, highlighting the effectiveness of integrating IRSs into UAV-enabled communication for enhanced reliability and efficiency.

Standalone Intelligent Reflecting Surface With Automatic Update of Phase-Shift Switching Schedule for Improved Communication and Localization

Standalone Intelligent Reflecting Surface With Automatic Update of Phase-Shift Switching Schedule for Improved Communication and Localization

Massive Wireless Energy Transfer Without Channel State Information via Imperfect Intelligent Reflecting Surfaces

Massive Wireless Energy Transfer Without Channel State Information via Imperfect Intelligent Reflecting Surfaces