725 citations · 3k across the 227 of their papers we have counts for
132 papers · 1 filter
Active Sensing for RIS-Aided Tracking and Power Control: A Hybrid Neuroevolution and Supervised Learning Approach
George Stamatelis, Hui Chen, Henk Henk Wymeersch +1
This paper studies energy efficient tracking of power-limited mobile users with the assistance of a Reconfigurable Intelligent Surface (RIS). Since localization pilot transmissions…
MIMO FSO Systems in Hybrid Quantum Noise Environments: SKR Analysis with One- and Two-way CV-QKD Protocols
Sushil Kumar, Soumya P. Dash, George C. Alexandropoulos
This paper studies a multiple-input multiple-output (MIMO) free-space optical (FSO) communication system employing continuous-variable quantum key distribution (CV-QKD), with the g…
Integrating Sensing and Communications in 6G? Not Until It Is Secure to Do So
Nanchi Su, Fan Liu, Jiaqi Zou +6
Integrated Sensing and Communication (ISAC) is emerging as a cornerstone technology for forthcoming 6G systems, significantly improving spectrum and energy efficiency. However, the…
Fluid Reconfigurable Intelligent Surfaces: Joint On-Off Selection and Beamforming with Discrete Phase Shifts
Han Xiao, Xiaoyan Hu, Kai-Kit Wong +3
This letter proposes a fluid reconfigurable intelligent surface (FRIS) paradigm, extending the conventional reconfigurable intelligent surface (RIS) technology to incorporate posit…
Evaluating Beam Sweeping for AoA Estimation with an RIS Prototype: Indoor/Outdoor Field Trials
Dimitris Vordonis, Dimitris Kompostiotis, Vassilis Paliouras +2
Reconfigurable Intelligent Surfaces (RISs) have emerged as a promising technology to enhance wireless communication systems by enabling dynamic control over the propagation environ…
Extremely Large Full Duplex MIMO for Simultaneous Downlink Communications and Monostatic Sensing at Sub-THz Frequencies
George C. Alexandropoulos, Ioannis Gavras
The in-band Full Duplex (FD) technology is lately gaining attention as an enabler for the emerging paradigm of Integrated Sensing and Communications (ISAC), which envisions seamles…
On the Rate-Exponent Region of Integrated Sensing and Communications With Variable-Length Coding
Ioannis Papoutsidakis, George C. Alexandropoulos
This paper considers the achievable rate-exponent region of integrated sensing and communication systems in the presence of variable-length coding with feedback. This scheme is fun…
Indoor Channel Characterization with Extremely Large Reconfigurable Intelligent Surfaces at GHz
Fabio Cardoso, Sérgio Matos, Luís M. Pessoa +1
The technology of Reconfigurable Intelligent Surfaces (RISs) is lately being considered as a boosting component for various indoor wireless applications, enabling wave propagation…
Lightweight Security for Ambient-Powered Programmable Reflections with Reconfigurable Intelligent Surfaces
Andreas Kunz, Sheeba Backia Mary Baskaran, George C. Alexandropoulos
Ambient Internet-of-Things (AIoT) form a new class of emerging technology that promises to deliver pervasive wireless connectivity to previously disconnected devices and products,…
RIS-Assisted MIMO CV-QKD at THz Frequencies: Channel Estimation and SKR Analysis
Sushil Kumar, Soumya P. Dash, Debasish Ghose +1
In this paper, a multiple-input multiple-output (MIMO) wireless system incorporating a reconfigurable intelligent surface (RIS) to efficiently operate at terahertz (THz) frequencie…
Optimal Multi-Level ASK Modulations for RIS-Assisted Communications with Energy-Based Noncoherent Reception
Sambit Mishra, Soumya P. Dash, George C. Alexandropoulos
This paper investigates the performance of one- and two-sided amplitude shift keying (ASK) modulations in noncoherent single-input single-output (SISO) wireless communication syste…
Characterization of Indoor RIS-Assisted Channels at 304 GHz: Experimental Measurements, Challenges, and Future Directions
George C. Alexandropoulos, Bo Kum Jung, Panagiotis Gavriilidis +7
Reconfigurable Intelligent Surfaces (RISs) are expected to play a pivotal role in future indoor ultra high data rate wireless communications as well as highly accurate three-dimens…
Evaluation of RIS-Enabled B5G/6G Indoor Positioning and Mapping using Ray Tracing Models
Dimitris Kompostiotis, Dimitris Vordonis, Vassilis Paliouras +2
A Reconfigurable Intelligent Surface (RIS) can significantly enhance network positioning and mapping, acting as an additional anchor point in the reference system and improving sig…
MIMO MAC Empowered by Reconfigurable Intelligent Surfaces: Capacity Region and Large System Analysis
Aris L. Moustakas, George C. Alexandropoulos
Smart wireless environments enabled by multiple distributed Reconfigurable Intelligent Surfaces (RISs) have recently attracted significant research interest as a wireless connectiv…
In-Band Full-Duplex MIMO Systems for Simultaneous Communications and Sensing: Challenges, Methods, and Future Perspectives
Besma Smida, George C. Alexandropoulos, Taneli Riihonen +1
In-band Full-Duplex (FD) Multiple-Input Multiple-Output (MIMO) systems offer a significant opportunity for Integrated Sensing and Communications (ISAC) due to their capability to r…
The Interference Broadcast Channel with Reconfigurable Intelligent Surfaces: A Cooperative Sum-Rate Maximization Approach
Konstantinos D. Katsanos, Paolo Di Lorenzo, George C. Alexandropoulos
This paper studies the interference broadcast channel comprising multiple multi-antenna Base Stations (BSs), each controlling a beyond diagonal Reconfigurable Intelligent Surface (…
Multi-User MISO with Stacked Intelligent Metasurfaces: A DRL-Based Sum-Rate Optimization Approach
Hao Liu, Jiancheng An, George C. Alexandropoulos +3
Stacked intelligent metasurfaces (SIMs) represent a novel signal processing paradigm that enables over-the-air processing of electromagnetic waves at the speed of light. Their mult…
Near-Field Beam Tracking with Extremely Large Dynamic Metasurface Antennas
Panagiotis Gavriilidis, George C. Alexandropoulos
The interplay between large antenna apertures and high frequencies in future generations of wireless networks will give rise to near-field communications. In this paper, we focus o…
Multi-RIS-Empowered Multiple Access: A Distributed Sum-Rate Maximization Approach
Konstantinos D. Katsanos, Paolo Di Lorenzo, George C. Alexandropoulos
The plethora of wirelessly connected devices, whose deployment density is expected to largely increase in the upcoming sixth Generation (6G) of wireless networks, will naturally ne…
Reconfigurable Intelligent Surfaces for THz: Hardware Impairments and Switching Technologies
Sérgio Matos, Yihan Ma, Qi Luo +10
The demand for unprecedented performance in the upcoming 6G wireless networks is fomenting the research on THz communications empowered by Reconfigurable Inteligent Surfaces (RISs)…
Cooperative Backscatter Communications with Reconfigurable Intelligent Surfaces: An APSK Approach
Qiang Li, Yehuai Feng, Miaowen Wen +4
In this paper, a novel amplitude phase shift keying (APSK) modulation scheme for cooperative backscatter communications aided by a reconfigurable intelligent surface (RIS-CBC) is p…
Secure ISAC MIMO Systems: Exploiting Interference With Bayesian Cramér-Rao Bound Optimization
Nanchi Su, Fan Liu, Christos Masouros +3
In this paper, we present a signaling design for secure integrated sensing and communication (ISAC) systems comprising a dual-functional multi-input multi-output (MIMO) base statio…
Joint Near-Field Target Tracking and Communications with Full Duplex Holographic MIMO
Ioannis Gavras, George C. Alexandropoulos
In this paper, we present a simultaneous target tracking and multi-user communications system realized by a full duplex holographic Multiple-Input Multiple-Output (MIMO) node equip…
Near-Field Localization with -bit Quantized Hybrid A/D Reception
Ioannis Gavras, Italo Atzeni, George C. Alexandropoulos
In this paper, we consider a hybrid Analog and Digital (A/D) receiver architecture with an extremely large Dynamic Metasurface Antenna (DMA) and an -bit resolution Analog-to-Dig…