Panagiotis Karkazis

Prof. Dr. Panagiotis Karkazis

University of West Attica, Athens, Attikí, Greece
orcid

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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24 September 2020 in Sensors
Verified
Journal Article
Open access
PDF file
PTPanagiotis Trakadas
Panagiotis Trakadas
PSPieter Simoens
Pieter Simoens
Panagiotis GkonisPanagiotis Gkonis
Panagiotis Gkonis
LSLambros Sarakis
Lambros Sarakis
AAAngelos Angelopoulos
Angelos Angelopoulos
Panagiotis KarkazisPanagiotis Karkazis
Panagiotis Karkazis
The digitization of manufacturing industry has led to leaner and more efficient production, under the Industry 4.0 concept. Nowadays, datasets collected from shop floor assets and information technology (IT) systems are used in data-driven analytics efforts to support more informed business intelligence decisions. However, these results are currently only used in isolated and dispersed parts of the production process. At the same time, full integration of artificial intelligence (AI) in all parts of manufacturing systems is currently lacking. In this context, the goal of this manuscript is to present a more holistic integration of AI by promoting collaboration. To this end, collaboration is understood as a multi-dimensional conceptual term that covers all important enablers for AI adoption in manufacturing contexts and is promoted in terms of business intelligence optimization, human-in-the-loop and secure federation across manufacturing sites. To address these challenges, the proposed architectural approach builds on three technical pillars: (1) components that extend the functionality of the existing layers in the Reference Architectural Model for Industry 4.0; (2) definition of new layers for collaboration by means of human-in-the-loop and federation; (3) security concerns with AI-powered mechanisms. In addition, system implementation aspects are discussed and potential applications in industrial environments, as well as business impacts, are presented.

15 April 2012 in Wireless Personal Communications
Verified
Journal Article
Closed access
PDF file
TZTheodore Zahariadis
Theodore Zahariadis
PTPanagiotis Trakadas
Panagiotis Trakadas
HLHelen Leligou
Helen Leligou
SMSotiris Maniatis
Sotiris Maniatis
Panagiotis KarkazisPanagiotis Karkazis
Panagiotis Karkazis

16 September 2021 in IEEE Access
Verified
Journal Article
Open access
Anastasios GiannopoulosAnastasios Giannopoulos
Anastasios Giannopoulos
SSSotirios Spantideas
Sotirios Spantideas
NKNikolaos Kapsalis
Nikolaos Kapsalis
Panagiotis KarkazisPanagiotis Karkazis
Panagiotis Karkazis
PTPanagiotis Trakadas
Panagiotis Trakadas
Energy efficiency (EE) constitutes a key target in the deployment of 5G networks, especially due to the increased densification and heterogeneity. In this paper, a Deep Q-Network (DQN) based power control scheme is proposed for improving the system-level EE of two-tier 5G heterogeneous and multi-channel cells. The algorithm aims to maximize the EE of the system by regulating the transmission power of the downlink channels and reconfiguring the user association scheme. To efficiently solve the EE problem, a DQN-based method is established, properly modified to ensure adequate QoS of each user (via defining a demand-driven rewarding system) and near-optimal power adjustment in each transmission link. To directly compare different DQN-based approaches, a centralized (C-DQN), a multi-agent (MA-DQN) and a transfer learning-based (T-DQN) method are deployed to address whether their applicability is beneficial in the 5G HetNets. Results confirmed that DQN-assisted actions could offer enhanced network-wide EE performance, as they balance the trade-off between the power consumption and achieved throughput (in Mbps/Watt). Excessive performance was observed for the MA-DQN approach (>5 Mbps/Watt), since the decentralized learning supports low-dimensional agents to be coordinated with each other through global rewards. In further comparing the T-DQN against MA-DQN solutions, T-DQN presents beneficial usage for very low or very high inter-cell distances, whereas the usage of MA-DQN is preferred (by a factor of ~1.3) for intermediate inter-cell distances (100-600m), where the power savings are feasible towards achieving increased EE. Furthermore, T-DQN scheme guarantees good EE solutions (above 2 Mbps/Watt), even for densely-deployed macro-cells, with effortless training and memory requirements. On the contrary, MA-DQN offers the best EE solutions at the expense of massive training resources and required training time.

1 February 2023 in Sensors
Verified
Journal Article
Open access
PDF file
AFAnastasios Fanariotis
Anastasios Fanariotis
TOTheofanis Orphanoudakis
Theofanis Orphanoudakis
KKKonstantinos Kotrotsios
Konstantinos Kotrotsios
VFVassilis Fotopoulos
Vassilis Fotopoulos
Georgios KeramidasGeorgios Keramidas
Georgios Keramidas
Panagiotis KarkazisPanagiotis Karkazis
Panagiotis Karkazis
Computing has undergone a significant transformation over the past two decades, shifting from a machine-based approach to a human-centric, virtually invisible service known as ubiquitous or pervasive computing. This change has been achieved by incorporating small embedded devices into a larger computational system, connected through networking and referred to as edge devices. When these devices are also connected to the Internet, they are generally named Internet-of-Thing (IoT) devices. Developing Machine Learning (ML) algorithms on these types of devices allows them to provide Artificial Intelligence (AI) inference functions such as computer vision, pattern recognition, etc. However, this capability is severely limited by the device’s resource scarcity. Embedded devices have limited computational and power resources available while they must maintain a high degree of autonomy. While there are several published studies that address the computational weakness of these small systems-mostly through optimization and compression of neural networks- they often neglect the power consumption and efficiency implications of these techniques. This study presents power efficiency experimental results from the application of well-known and proven optimization methods using a set of well-known ML models. The results are presented in a meaningful manner considering the “real world” functionality of devices and the provided results are compared with the basic “idle” power consumption of each of the selected systems. Two different systems with completely different architectures and capabilities were used providing us with results that led to interesting conclusions related to the power efficiency of each architecture.

1 July 2012
Verified
Conference Paper
Closed access
Panagiotis KarkazisPanagiotis Karkazis
Panagiotis Karkazis
HLHelen Leligou
Helen Leligou
LSLambros Sarakis
Lambros Sarakis
TZTheodore Zahariadis
Theodore Zahariadis
PTPanagiotis Trakadas
Panagiotis Trakadas
CCChristos Capsalis
Christos Capsalis
The diversity of applications that current and emerging Wireless Sensor Networks (WSNs) are called to support imposes different requirements on the underlying network with respect to delay and loss, while at the same time the WSN imposes its own intricacies. The satisfaction of these requirements highly depends on the metric upon which the forwarding routes are decided. In this view, the IETF ROLL group has proposed the RPL routing protocol, which can flexibly work on various routing metrics, as long as they hold specific properties. The system implementer/user is free to decide whether to use one or multiple routing metrics, as well as the way these metrics can be combined. In this paper, we provide ways to quantify the routing metrics so that they can be combined in an additive or lexical manner. We use extensive simulation results to evaluate the impact of several routing metrics on the achieved performance.

Verified
Journal Article
Open access
PDF file
PTPanagiotis Trakadas
Panagiotis Trakadas
Panagiotis KarkazisPanagiotis Karkazis
Panagiotis Karkazis
HLHelen Leligou
Helen Leligou
TZTheodore Zahariadis
Theodore Zahariadis
FVFelipe Vicens
Felipe Vicens
Dimosthenis KyriazisDimosthenis Kyriazis
Dimosthenis Kyriazis
5G is considered to be the technology that will accommodate the development and management of innovative services with stringent and diverse requirements from end users, calling for new business models from the industry. In this context, the development and efficient management of Network Services (NS) serving specific vertical industries and spanning across multiple administrative domains and heterogeneous infrastructures is challenging. The main challenges regard the efficient provision of NSs considering the Quality of Service (QoS) requirements per vertical industry along with the optimal usage of the allocated resources. Towards addressing these challenges, this paper details an innovative approach that we have developed for managing and orchestrating such NSs, called SONATA, and compare it with OSM and Cloudify, which are two of the most known open-source Management and Orchestration (MANO) frameworks. In addition to examining the supported orchestration mechanisms per MANO framework, an evaluation of main operational and functional KPIs is provided based on experimentation using a real testbed. The final aim is the identification of their strong and weak points, and the assessment of their suitability for serving diverse vertical industry needs, including of course the Internet of Things (IoT) service ecosystem.