Alexandros I. Papadopoulos

dblp:254/8544 · DBLP profile ↗
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7ranked-venue papers
6as first author
6since 2021 · last 2026
0000-0002-4965-2478ORCID · reported

Domains — the database's venue-derived domains; a paper can count in several

Computer networks · 4 · 3 first-author · 4 since 2021
YearPublicationVenuePosition
2026 Physics-Aware RIS Codebook Compilation for Near-Field Beam Focusing under Mutual Coupling and Specular Reflections
Alexandros I. Papadopoulos, Maria Anna Pistela, Dimitrios Tyrovolas, Antonios Lalas, Konstantinos Votis, Sotiris Ioannidis, George K. Karagiannidis, Christos Liaskos
ICC1
2026 A Novel Framework for Fair Resource Allocation in RIS-Enabled Networks
Alexandros I. Papadopoulos, Antonios Lalas, Konstantinos Votis, Leandros Tassiulas, Christos Liaskos
WoWMoM1
2025 SHIELD: A Codebook-Based Methodology for RIS-Based Covert Communications
abstract
Programmable Wireless Environments (PWEs) leverage Reconfigurable Intelligent Surfaces (RISes) to actively shape electromagnetic (EM) propagation, enabling advanced control over wireless channels. Beyond improved performance in B5G/6G networks, this control also introduces new security capabilities. Exploiting this, we propose RF-Fencing: a service that selectively suppresses EM signals toward eavesdroppers while preserving reliable communication for legitimate users, thereby significantly enhancing network covertness. Building on that, in this paper, we introduce SHIELD, the first RF-Fencing algorithm that partitions the PWE into Signal Suppression Areas (SSAs) and Signal Delivery Areas (SDAs) through on-the-fly merging of RIS configurations. Extensive EM analysis confirms SHIELD’s effectiveness in preventing wardens from intercepting critical information and achieving covert communications with minimal impact on legitimate users. Moreover, SHIELD can serve also as a jamming-mitigation mechanism and is applicable across various frequency bands and RIS designs.
Alexandros I. Papadopoulos, Dimitrios Tyrovolas, Alexandros Pitilakis, Panagiotis D. Diamantoulakis, Antonios Lalas, Konstantinos Votis, Nikolaos V. Kantartzis, Sotiris Ioannidis, Christos Liaskos
PIMRC1
2025 On Modeling the RIS as a Resource: Multi-User Allocation and Efficiency-Proportional Pricing
abstract
Programmable Wireless Environments aim to render the communication environment a controllable, software-defined medium. Reconfigurable Intelligent Surfaces (RISes) are the key enabling technology, which can offer the real-time capability to manipulate impinging waves. RISes are expected to be widely deployed in B5G/6G networks to serve a large number of users simultaneously. Despite numerous analyses highlighting the benefits of utilizing previously unexploitable propagation factors through the use of RISes, there is a lack of analysis regarding their relation to the concept of network resource, their allocation to users/stakeholders and their fair pricing. Thus, this paper models RISes as networked resources. Based on this definition, the PRIME algorithm is proposed, the first algorithm for RIS resource allocation and joint pricing. PRIME strives for proportionality between the offered end-user performance level and the corresponding resource pricing, promoting fairness. The algorithm is validated via full-wave electromagnetic simulations and applies to multiple RIS functionalities and frequency bands.
Alexandros I. Papadopoulos, Dimitrios Tyrovolas, Antonios Lalas, Konstantinos Votis, Stefan Schmid 0001, Sotiris Ioannidis, George K. Karagiannidis, Christos Liaskos
IEEE Trans. Netw. Serv. Manag.1
2024 CoopeRIS: A framework for the simulation of reconfigurable intelligent surfaces in cooperative driving environments
abstract
Future connected vehicles will require high-performance communication technologies for advanced cooperative driving applications such as maneuvering and cooperative perception. mmWave communications can meet the bandwidth requirements of such applications, but the typically harsh propagation conditions of vehicular environments hinder the broad adoption of mmWave devices on cars. Reconfigurable intelligent surfaces (RISs) can help mitigate this problem by enabling the reflection of signals in a configurable direction. In turn, this can result in more stable non-line of sight (NLoS) links whenever a LoS path is not available. RISs have recently gained attention in the vehicular domain but, while providing benefits, they also introduce a lot of research challenges. To measure their effectiveness at scale, it is necessary to develop simulation tools that can reproduce their characteristics with high fidelity and federate them with existing cooperative driving simulation frameworks. In this work we present CoopeRIS, an open-source simulation framework federated within the Plexe/Veins/SUMO ecosystem, capable of modeling and simulating RIS-based mmWave communications in a vehicular environment. We exploit CoopeRIS to perform an initial feasibility study, highlighting the challenges ahead and the performance RISs need to deliver in order to enable this type of communication. In addition we propose a method to combine multiple RIS configurations into a single one to enable multi-user service delivery, showing its performance via CoopeRIS. The insights we presents within this work show the potential of such simulation framework and thus how the community can build further research work on top if it.
Michele Segata, Paolo Casari, Marios Lestas, Alexandros I. Papadopoulos, Dimitrios Tyrovolas, Taqwa Saeed, George K. Karagiannidis, Christos Liaskos
Comput. Networks4
2022 An Open Platform for Simulating the Physical Layer of 6G Communication Systems with Multiple Intelligent Surfaces
abstract
Reconfigurable Intelligent Surfaces (RIS) constitute a promising technology that could fulfill the extreme performance and capacity needs of the upcoming 6G wireless networks, by offering software-defined control over wireless propagation phenomena. Despite the existence of many theoretical models describing various aspects of RIS from the signal processing perspective (e.g., channel fading models), there is no open platform to simulate and study their actual physical-layer behavior, especially in the multi-RIS case. In this paper, we develop an open simulation platform, aimed at modeling the physical-layer electromagnetic coupling and propagation between RIS pairs. We present the platform by initially designing a basic unit cell, and then proceeding to progressively model and simulate multiple and larger RISs. The platform can be used for producing verifiable stochastic models for wireless communication in multi-RIS deployments, such as vehicle-to-everything (V2X) communications in autonomous vehicles and cybersecurity schemes, while its code is freely available to the public.
Alexandros I. Papadopoulos, Antonios Lalas, Konstantinos Votis, Dimitrios Tyrovolas, George K. Karagiannidis, Sotiris Ioannidis, Christos Liaskos
CNSM1
2019 Development of Highly Accurate IoT-Ready Quaternion-based 3D Gradiometer based on COTS IMUs
abstract
This paper introduces a Quaternion-based rotational representation of low power, low resource, commercial-of-the-shelf (COTS) IMU sensors, offering high accuracy, reliability and real time performance. A critical aspect of this work is the distributed implementation of the proposed solution that facilitates its integration with IoT platforms utilizing the MQTT communication protocol while efficiently applying a modified Madgwick's filter implementation to extract the sensor's orientation and rotation. Based on the proposed solution, sensor orientation outperforms conventional implementations based on previously widely applied methods like Euler Angles and effectively tackles important shortcomings such as a sluggish response and issues like Gimbal Lock. Comprehensive, experimental evaluation reveals that the proposed solution yields state-of-the-art accuracy, while being deployed on a typical, low-cost COTS sensor while delay measurements indicate a highly reliable and time constrained performance adequate for a wide range of real life scenarios.
Alexandros I. Papadopoulos, Christos P. Antonopoulos, Konstantinos Antonopoulos, Nikos S. Voros, Stavros A. Koubias
WiMob1