S. Chatzinotas

Exploiting Movable-Element STARS for Rate Splitting Multiple Access

This paper investigates a movable-element simultaneously transmitting and reflecting reconfigurable intelligent surface (ME-STARS) assisted rate-splitting multiple access (RSMA) system under imperfect channel state information (CSI). Unlike conventional STARS with fixed element positions, the elements of ME-STARS can b...

Leveraging Movable-Element STARS for RSMA-SWIPT Under Practical System Imperfections

We study a robust multiuser framework for simultaneous wireless information and power transfer (SWIPT), where rate-splitting multiple access (RSMA) is integrated with a movable-element simultaneously transmitting and reflecting surface (ME-STARS). By allowing the STARS elements to change their positions in addition to...

Cost-Effective Antenna Terminals for Direct-to-Vehicle Satellite Communications

Stacked Fluid Metasurfaces: Mutual-Coupling-Aware Modeling and Optimization

Stacked intelligent metasurfaces process the transmitted field layer by layer, and fluid antennas make the position of every radiator a design variable. Combined, they pack radiators at sub-wavelength spacings within and across layers, where mutual coupling governs the physics that current models omit. This paper devel...

Polarforming-Enabled Power-Splitting SWIPT: A GNN-Based Optimization Approach

Simultaneous wireless information and power transfer (SWIPT) is a critical technology for the future of the Internet of Things (IoT). However, ensuring a stable power supply in such networks remains a significant challenge. This work introduces dynamic polarization control as an additional degree of freedom (DoF) in SW...

Hierarchical Codebook-Based Analog Beamforming Design for SIM-Assisted Communication Systems

Stacked intelligent metasurface (SIM) can perform signal processing in the wave domain by intelligently optimizing the phase shifts of transmissive meta-elements on each layer. However, it typically requires high overhead to acquire channel state information. In this letter, we propose a hierarchical codebook design fo...

Block-Level Interference Exploitation Precoding for BD-RIS-Aided Communication Systems

The constructive interference (CI)-based block-level precoding (CI-BLP) approach reduces computational complexity compared to conventional CI-based symbol-level precoding (CI-SLP) and provides additional design flexibility due to its relaxed block-level design. However, using a constant precoding matrix within each blo...

Impact of Out-of-Band Emissions From Active Antenna Systems on LEO Satellite Downlink Coexistence in the C-Band

The coexistence between terrestrial 5G networks and low Earth orbit (LEO) satellite systems in the C-band has raised increasing concerns due to the aggregated impact of out-of-band emissions (OOBE) from active antenna systems (AAS). This paper investigates the interference generated by terrestrial 5G downlink transmiss...

Terahertz Inter-Satellite Links: Motivation, Challenges and Opportunities

Inter-satellite links (ISLs) are essential to the evolution of next-generation satellite constellations, providing the foundation for low-latency, resilient, and globally scalable connectivity. While low radio-frequency (RF)-based ISLs offer technological maturity, they are increasingly constrained by spectrum scarcity...

Distributed Receive Beamforming for Multi-Satellite Networks With Multiple Ground-Based Nodes Under Fronthaul Constraints

Future multi-satellite networks can enhance downlink reliability through cooperative reception at geographically distributed ground nodes (GNs), but limited fronthaul restricts centralized signal collection and instantaneous channel state information (CSI) exchange. We develop distributed beamforming where GNs combine...

GNN-Based Polarforming for Multi-User MISO Short-Packet URLLC under Imperfect CSI

This paper investigates polarization-aware transmission for multi-user multiple-input single-output (MU-MISO) short-packet ultra-reliable low-latency communications (URLLC) under imperfect channel state information (CSI). We consider a system in which the base station (BS) and users are equipped with polarization-recon...

A Survey of Quantum Key Distribution Networks: Architectures, Hardware Platforms, and Control-Plane Integration

This survey provides an infrastructure-oriented review of QKD networks, examining architectural models, quantum randomness as a root of trust, FPGA and system-on-chip (SoC) based acceleration techniques, and programmable control-plane integration.