- Department of Electrical and Computer Engineering
Aristotle University of Thessaloniki
Egnatia Str., Building D, Floor 6
54 124 Thessaloniki, Greece - (+30) 2310994178
- Communication, Software Engineering, Computer Networks, Communication Theory, Metamaterials, Plasmonics, Electrical and Computer Engineering (ECE), and 11 moreTelecommunications Engineering, Spectrum Sensing, Heterogeneous Networks, Wireless Communications, Cognitive Radio Networks, MIMO Systems, Electrical and Computer Engineering, IEEE Standards, Wireless Body Area Network (WBAN), Wireless MAC protocols, and Intelligent cityedit
Research Interests:
Research Interests:
The transformation of the conventional electrical grid into a digital ecosystem brings significant benefits, such as two-way communication between energy consumers and utilities, self-monitoring and pervasive controls. However, the advent... more
The transformation of the conventional electrical grid into a digital ecosystem brings significant benefits, such as two-way communication between energy consumers and utilities, self-monitoring and pervasive controls. However, the advent of the smart electrical grid raises severe cybersecurity and privacy concerns, given the presence of legacy systems and communications protocols. This paper focuses on False Data Injection (FDI) cyberattacks against a low-voltage distribution system, taking full advantage of Man In The Middle (MITM) actions. The first cyberattack targets the communication between a smart meter and an Active Distribution Management System (ADMS), while the second FDI cyberattack targets the communication between a smart inverter and ADMS. In both cases, the cyberattacks affect the operation of the distribution transformer, thus resulting in devastating consequences. Moreover, this paper provides an Artificial Intelligence (AI)-based Intrusion Detection System (IDS), detecting and mitigating the above cyberattacks in a timely manner. The evaluation results demonstrate the efficiency of the proposed IDS.
Research Interests:
Research Interests:
The next generation wireless networks are envisioned to deal with the expected thousand-fold increase in total mobile broadband data and the hundred-fold increase in connected devices. In order to provide higher data rates, improved... more
The next generation wireless networks are envisioned to deal with the expected thousand-fold increase in total mobile broadband data and the hundred-fold increase in connected devices. In order to provide higher data rates, improved end-to-end performance, low latency, and low energy consumption at a low cost per transmission, the fifth generation (5G) systems are required to overcome various handicaps of current cellular networks and wireless links. One of the key handicaps of 5G systems is the performance degradation of the communication link, due to the use of low-cost transceiver in high data rate. Motivated by this in this paper, we discuss the impact of transceiver front-end hardware imperfections on the spectrum sensing performance of cognitive radios.
Research Interests:
This thesis investigates the influence of interference in wireless systems, revisits promising interference management solutions, as well as studies the impact of interference, caused by hardware imperfections, on the performance of the... more
This thesis investigates the influence of interference in wireless systems, revisits promising interference management solutions, as well as studies the impact of interference, caused by hardware imperfections, on the performance of the wireless link and propose countermeasures. The thesis is divided into two parts. In the first part of the thesis, different types of interference and modern interference management solutions, which are expected to be used in the future wireless networks, are reviewed. Moreover, the influence of fading and interference, due to the existence of multiple possible users operating simultaneously in the same carrier frequency, on the spectrum sensing capability of an energy detector (ED) is investigated. Analytical tools for the performance evaluation of this problem are derived, while the problem of appropriately selecting the detection threshold and the sensing duration, in order to satisfy a specific requirement, is discussed. The offered analytical fra...
Research Interests:
This deliverable includes the work conducted within Task 1.1 "Use cases definition and system requirements specification". The main objective of this task is to define the use cases and a set of requirements that will be the... more
This deliverable includes the work conducted within Task 1.1 "Use cases definition and system requirements specification". The main objective of this task is to define the use cases and a set of requirements that will be the basis for all further work. Each use case contains scenarios in order to organize the technical work efficiently and focus on ARIADNE challenges and innovations. Thus, Deliverable 1.1 presents an overview of the ARIADNE system concept, a detailed description of each use case and corresponding scenarios, the resulting analysis on the definition of the main Key Performance Indicators (KPI) that each use case and the ARIADNE system target to satisfy and, finally, a description of how the machine learning techniques will be applied in the framework of ARIADNE.
In this letter, we introduce a novel mixed terahertz (THz)-radio frequency (RF) wireless system architecture, which can be used for backhaul/fronthaul applications, and we deliver the theoretical framework for its performance assessment.... more
In this letter, we introduce a novel mixed terahertz (THz)-radio frequency (RF) wireless system architecture, which can be used for backhaul/fronthaul applications, and we deliver the theoretical framework for its performance assessment. In more detail, after identifying the main design parameters and characteristics, we derive novel closed-form expressions for the end-to-end signal-to-noise ratio cumulative density function, the outage probability, and the symbol error rate, assuming that the system experiences the joint effect of fading and stochastic antenna misalignment. The derived analytical framework is verified through simulations and quantifies the system's effectiveness and reliability. Finally, our results contribute to the extraction of useful design guidelines.
Research Interests:
a variety of challenging telecommunication topics ranging from background fields like signals, traffic, coding, communication basics up to large communication systems and networks, fixed, mobile and integrated, etc. Applications,... more
a variety of challenging telecommunication topics ranging from background fields like signals, traffic, coding, communication basics up to large communication systems and networks, fixed, mobile and integrated, etc. Applications, services, system and network management issues also received significant attention. The spectrum of 21st Century telecommunications is marked by the arrival of new business models, new platforms, new architectures and new customer profiles. Next generation networks, IP multimedia systems, IPTV, and converging network and services are new telecommunications paradigms. Technology achievements in terms of coexistence of IPv4 and IPv6, multiple access technologies, IP-MPLS network design driven methods, multicast and high speed require innovative approaches to design and develop large scale telecommunications networks. Mobile and wireless communications add profit to large spectrum of technologies and services. We witness the evolution 2G, 2.5G, 3G and beyond, ...
Research Interests:
Research Interests:
Research Interests: Computer Science and IEEE
In the present work, we introduce a novel cochlear implant (CI) architecture, namely all-optical CI (AOCI), which directly converts acoustic to optical signals capable of stimulating the cochlear neurons. First, we describe the... more
In the present work, we introduce a novel cochlear implant (CI) architecture, namely all-optical CI (AOCI), which directly converts acoustic to optical signals capable of stimulating the cochlear neurons. First, we describe the building-blocks (BBs) of the AOCI, and explain their functionalities as well as their interconnections. Next, we present a comprehensive system model that incorporates the technical characteristics and constraints of each BB, the transdermal-optical-channel particularities, i.e., optical path-loss and external-implanted device stochastic pointing-errors, and the cochlear neurons biological properties. Additionally, in order to prove the feasibility of the AOCI architecture, we conduct a link-budget analysis that outputs novel closed-form expressions for the instantaneous and average photon flux that is emitted on the cochlear neurons. Likewise, we define three new key-performance-indicators (KPIs), namely probability of hearing, probability of false-hearing, ...
Research Interests:
The present white paper focuses on the system requirements of TERRANOVA. Initially details the key use cases for the TERRANOVA technology and presents the description of the network architecture. In more detail, the use cases are... more
The present white paper focuses on the system requirements of TERRANOVA. Initially details the key use cases for the TERRANOVA technology and presents the description of the network architecture. In more detail, the use cases are classified into two categories, namely backhaul & fronthaul and access and small cell backhaul. The first category refers to fibre extender, point-to-point and redundancy applications, whereas the latter is designed to support backup connection for small and medium-sized enterprises (SMEs), internet of things (IoT) dense environments, data centres, indoor wireless access, ad hoc networks, and last mile access. Then, it provides the networks architecture for the TERRANOVA system as well as the network elements that need to be deployed. The use cases are matched to specific technical scenarios, namely outdoor fixed point-to-point (P2P), outdoor/indoor individual point-to-multipoint (P2MP), and outdoor/indoor "quasi"-omnidirection, and the key perfor...
Polar codes have been proven to be capacity achieving for any binary-input discrete memoryless channel, while at the same time they can reassure secure and reliable transmission over the single-input single-output wireless channel.... more
Polar codes have been proven to be capacity achieving for any binary-input discrete memoryless channel, while at the same time they can reassure secure and reliable transmission over the single-input single-output wireless channel. However, the use of polar codes to secure multiple-antenna transmission and reception has not yet been reported in the open literature. In this paper, we assume a multiple-input multiple-output wiretap channel, where the legitimate receiver and the eavesdropper are equipped with the same number of antennas. We introduce a protocol that exploits the properties of both physical and media access control layer security by employing polar coding and encryption techniques in a hybrid manner in order to guarantee secure transmission. A novel security technique is also proposed, where a cryptographic key is generated based on the information transmitted and renewed every transmission block without the need for a separate key exchange method. Finally, to illustrat...
Research Interests:
Internet of things (IoT) changes significantly the requirements for connectivity, mainly with regards to long battery life, low device cost, low deployment cost, extended coverage and support for a massive number of devices. Driven from... more
Internet of things (IoT) changes significantly the requirements for connectivity, mainly with regards to long battery life, low device cost, low deployment cost, extended coverage and support for a massive number of devices. Driven from these requirements, several different cellular and non-cellular low power wide area network (LPWAN) solutions are emerging and competing for IoT business and the overall connectivity market. Motivated by this, in this paper, we review and compare the design specifications of different LPWAN solutions, as well as, we discuss their suitability for different IoT applications. Finally, we present the challenges, future trends, and potential research directions for LPWANs.
Research Interests:
This paper presents an analytical pathloss model for reconfigurable intelligent surface (RIS) assisted terahertz (THz) wireless systems. Specifically, the model accommodates both the THz link and the RIS particularities. Finally, we... more
This paper presents an analytical pathloss model for reconfigurable intelligent surface (RIS) assisted terahertz (THz) wireless systems. Specifically, the model accommodates both the THz link and the RIS particularities. Finally, we derive a closed-form expression that returns the optimal phase shifting of each RIS reflection unit. The derived pathloss model is validated through extensive electromagnetic simulations and is expected to play a key role in the design of RIS-assisted THz wireless systems.
Research Interests:
Research Interests:
Next generation in-to-out-of body biomedical applications have adopted optical wireless communications (OWCs). However, by delving into the published literature, a gap is recognised in modeling the in-to-out-of channel, since most... more
Next generation in-to-out-of body biomedical applications have adopted optical wireless communications (OWCs). However, by delving into the published literature, a gap is recognised in modeling the in-to-out-of channel, since most published contributions neglect the particularities of different type of tissues. Towards this direction, in this paper we present a novel pathloss and scattering models for in-to-out-of OWC links. Specifically, we derive extract analytical expressions that accurately describe the absorption of the five main tissues’ constituents, namely fat, water, melanin, oxygenated and de-oxygenated blood. Moreover, we formulate a model for the calculation of the absorption coefficient of any generic biological tissue. Next, by incorporating the impact of scattering in the aforementioned model we formulate the complete pathloss model. The developed theoretical framework is verified by means of comparisons between the estimated pathloss and experimental measurements fro...
Research Interests:
In this work, we examine the use of reconfigurable intelligent surfaces (RISs) to create alternative paths from a transmitter to a receiver in millimeter-wave (mmWave) networks, when the direct link is blocked. In this direction, we... more
In this work, we examine the use of reconfigurable intelligent surfaces (RISs) to create alternative paths from a transmitter to a receiver in millimeter-wave (mmWave) networks, when the direct link is blocked. In this direction, we evaluate the end-to-end signal-to-noise ratio (SNR) expression of the transmitter-RIS-receiver links that take into account the transmitter-RIS and RIS-receiver distances and enables us to acquire important insights regarding the RIS position that maximizes it. Finally, the insights are corroborated by numerical results.
Research Interests:
Research Interests:
Research Interests:
Η μελέτη και σχεδίαση των σύγχρονων δικτύων ασύρματων επικοινωνιών επιβάλλει την υιοθέτηση αποτελεσματικών τεχνικών για την καταπολέμηση των παρεμβολών προκειμένου να εξασφαλίζεται η ταυτόχρονη πρόσβαση των χρηστών σε... more
Η μελέτη και σχεδίαση των σύγχρονων δικτύων ασύρματων επικοινωνιών επιβάλλει την υιοθέτηση αποτελεσματικών τεχνικών για την καταπολέμηση των παρεμβολών προκειμένου να εξασφαλίζεται η ταυτόχρονη πρόσβαση των χρηστών σε εφαρμογές που απαιτούν υψηλό ρυθμό μετάδοσης δεδομένων και μεγάλη αξιοπιστία σε πραγματικό χρόνο. Η παραπάνω ανάγκη γίνεται συνεχώς και πιο επιτακτική εξαιτίας της ολοένα αυξανόμενης πυκνότητας των χρηστών, αλλά και των περιορισμένων διαθέσιμων πόρων σε φάσμα που έχει οδηγήσει σταδιακά στη χρήση τεχνικών πολλαπλών φερόντων για επικοινωνία άνω και κάτω ζεύξης τόσο σ τα επίγεια όσο και σ τα δορυφορικά συσ τήματα νέας γενιάς. Η διδακτορική διατριβή οργανώνεται σε δύο μέρη. Το πρώτο μέρος είναι αφιερωμένο στα διαφορετικά είδη των παρεμβολών, τις επιπτώσεις τους και τους τρόπους αντιμετώπισης τους σε σύγχρονα και μελλοντικά συστήματα ασυρμάτων επικοινωνιών. Επιπλέον, εξετάζεται η επίδραση των ομοκ...
Research Interests:
Research Interests:
Research Interests:
In this paper, we assess the signal quality of the out-body to in-body optical communication link, which can be used as a fundamental enabler of novel biomedical appliances, such as medical implants, as well as biological and chemical... more
In this paper, we assess the signal quality of the out-body to in-body optical communication link, which can be used as a fundamental enabler of novel biomedical appliances, such as medical implants, as well as biological and chemical components monitoring. In particular, we present a mathematical understanding of the transdermal system, which takes into account the optical channel characteristics, the integrated area limitations of the in-body unit, the transceivers’ pointing errors and the particularities of the optical units. Moreover, to accommodate the propagation characteristics, we present a novel simplified, but accurate, transdermal path-gain model. Finally, we extract low-complexity closed-form expressions for the instantaneous and average signal to noise ratio of the transdermal optical link (TOL). Numerical and simulation results are provided for several insightful scenarios and reveal that pointing errors can significantly affect the reliability and effectiveness of the...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Engineering, Electronic Engineering, Computer Science, Technology, Wireless Communications, and 9 moreFading Channel, Fading, RF impairments, Cascaded Fading Channels, Hardware– constrained Communications, Double Rayleigh, Triple Rayleigh, Single-carrier communications, and Mutli-Carrier Communications
Research Interests:
Research Interests:
In this paper, we implement the MIMO link adaptation (LA) with carrier aggregation (CA) in LTE-Advanced (LTE-A) heterogeneous networks (HetNets). The considered HetNet involves macro- and pico- eNode base stations, which implement... more
In this paper, we implement the MIMO link adaptation (LA) with carrier aggregation (CA) in LTE-Advanced (LTE-A) heterogeneous networks (HetNets). The considered HetNet involves macro- and pico- eNode base stations, which implement multiple input multiple output (MIMO), link adaptation (LA) with the appropriate feedback and CA technologies for the communication with a single user equipment. We present an enhanced MIMO LA algorithm, which facilitates the improvement of the total throughput when CA is employed in HetNets. In particular, the performance of the LTE-A physical downlink channel is assessed in terms of throughput, assuming that the proposed algorithm is utilized in a closed-loop spatial multiplexing MIMO wireless system under non-continuous heterogeneous CA. Furthermore, we present the impact of different LTE-A fading channel models and outdated feedback on the LA algorithm performance.
Research Interests:
Research Interests:
Research Interests:
Research Interests: Probability, OFDM, Protocols, Radio Frequency, Dual Hop Relaying Networks, and 10 moreOpportunistic relaying, Interference, AF Relaying, Vectors, Maximum Ratio Combining, Signal to Noise Ratio, Electrical And Electronic Engineering, Orthogonal Frequency Division Multiplexing, RF impairments, and OFDM modulation
This paper focuses on delivering quantified results for the evaluation of the aggregated impact of stochastic antenna misalignment, multipath fading and hardware imperfections on the terahertz (THz) wireless fiber extenders. In this line,... more
This paper focuses on delivering quantified results for the evaluation of the aggregated impact of stochastic antenna misalignment, multipath fading and hardware imperfections on the terahertz (THz) wireless fiber extenders. In this line, we present the appropriate signal model that accommodates the different technical and environmental parameters. In particular, it takes into consideration the antenna gains, the central frequency, the transmission range, the environmental conditions, i.e. temperature, humidity and pressure, the spatial jitter between the transmitter and receiver antennas, which results to antenna misalignment, the intensity of hardware imperfections, and the stochastic behavior of the wireless channel. Based on this model, we assess the joint impact of antenna misalignment and multipath fading, by providing Monte Carlo simulation results for the channels ergodic capacity.
With the vision to transform the current wireless network into a cyber-physical intelligent platform capable of supporting bandwidth-hungry and latency-constrained applications, both academia and industry turned their attention to the... more
With the vision to transform the current wireless network into a cyber-physical intelligent platform capable of supporting bandwidth-hungry and latency-constrained applications, both academia and industry turned their attention to the development of artificial intelligence (AI) enabled terahertz (THz) wireless networks. In this article, we list the applications of THz wireless systems in the beyond fifth generation era and discuss their enabling technologies and fundamental challenges that can be formulated as AI problems. These problems are related to physical, medium/multiple access control, radio resource management, network and transport layer. For each of them, we report the AI approaches, which have been recognized as possible solutions in the technical literature, emphasizing their principles and limitations. Finally, we provide an insightful discussion concerning research gaps and possible future directions.