Eleftherios Stergiou

Ensuring Quality of Service (QoS) in complex, large scale, and centralized Software-Defined Networking (SDN) environments remains a major challenge for the scientific community, network administrators or operators, and industry. The SDN networking model promises to improve and optimize QoS in dynamic environments by enhancing network applications related to traffic management. It provides centralized control, flexibility, abstraction, and programmability of network resources. However, these expectations have not been fully met, primarily due to the difficulties associated with integrating or adapting traditional QoS mechanisms (routing, queue management, resource reservation) into the SDN architecture, the limitations of the OpenFlow protocol, and the highly dynamic nature of modern networks. Given the wide variety of networking environments, such as Internet of Things (IoT), data centers, cloud compounding, fog computing, 5G/6G networks and others, the core challenge is the lack of a standardized workflow for the integration of QoS mechanisms into SDN. Previous studies primarily focus on specific QoS mechanisms in SDN, particular application domains, or architectural aspects, offering limited comprehensive comparisons of QoS requirements, implementation approaches, evaluation methodologies, and the limitations of individual studies. To address these gaps, this study combines bibliometric analysis with a systematic review of selected publications from 2020 to 2026, providing an up-to-date and comprehensive overview of the latest research advances, emerging trends, and technological developments in the field. Furthermore, it critically examines the QoS requirements, implementation approaches, evaluation methodologies, and limitations reported in the selected studies, thereby offering a structured synthesis of the current state of the art and identifying promising directions for future research.

5G technology was introduced in 2019 with the aim of transforming digital connectivity, enabling a new generation of communication capabilities, such as significantly faster mobile broadband, highly reliable low-latency links, and the capacity to support vast IoT deployments. However, the expected improvements promised by 5G technology do not seem to be reflected in actual usage. This study aims to address the issue of the real-world usage of 5G telecommunications networks and compare it with the theoretical specifications of the network as officially published by 3GPP. Specifically, the focus will be on the evaluation of the implementation of the 5G network in northwestern Greece, which operates in Non-Standalone (NSA) mode as of the date of this study’s completion. 5G Standalone (SA) networks were not available for public testing in this region during the data collection period. The analysis focuses on key performance indicators, including throughput, latency, stability, and coverage, to assess how effectively current deployments meet the expectations set by 5G standards. Results show that while 5G delivers notable improvements in peak data rates and latency, several practical limitations persist. NSA deployments remain constrained by their dependence on 4G infrastructure, resource sharing between LTE and 5G components affects performance under high-load conditions, and inconsistent coverage leads to significant variability in user experience. These findings highlight the gap between theoretical capabilities and operational performance, offering insights that can guide future network optimization and inform the transition toward 5G Standalone (SA) architectures.

The classification of Software-Defined Networking (SDN) traffic is an essential tool for network management, network monitoring, traffic engineering, dynamic resource allocation planning, and applying Quality of Service (QoS) policies. The programmability nature of SDN, the holistic view of the network through SDN controllers, and the capability for dynamic adjustable and reconfigurable controllersare fertile ground for the development of new techniques for traffic classification. Although there are enough research works that have studied traffic classification methods in SDN environments, they have several shortcomings and gaps that need to be further investigated. In this study, we investigated traffic classification methods in SDN using publicly available SDN traffic trace datasets. We apply a series of classifiers, such as MLP (BFGS), FC2 (RBF), FC2 (MLP), Decision Tree, SVM, and GENCLASS, and evaluate their performance in terms of accuracy, detection rate, and precision. Of the methods used, GenClass appears to be more accurate in separating the categories of the problem than the rest, and this is reflected in both precision and recall. The key element of the GenClass method is that it can generate classification rules programmatically and detect the hidden associations that exist between the problem features and the desired classes. However, Genetic Programming-based techniques require significantly higher execution time compared to other machine learning techniques. This is most evident in the feature construction method where at each generation of the genetic algorithm, a set of learning models is required to be trained to evaluate the generated artificial features.

Comprehensive Analysis of Software-Defined Networking: Evaluating Performance Across Diverse Topologies and Investigating Topology Discovery Protocols by Nikolaos V. Oikonomou 1,* , Dimitrios V. Oikonomou 2 Eleftherios Stergiou 1 Dimitrios Liarokapis 1 1 Department of Informatics & Telecommunications, University of Ioannina, Arta,47150, Greece 2 Department of Regional & Cross Border Studies, University of Western Macedonia, … Continue reading "Comprehensive Analysis of Software-Defined Networking: Evaluating Performance Across Diverse Topologies and Investigating Topology Discovery Protocols"

Software-defined network (SDN) technology can offer wireless networks the advantages of simplified control and network management. This SDN subdomain technology is called the software-defined wireless network (SDWN). In this study, the performance of four controllers in an SDWN environment is assessed, since the controller is the most significant component of the entire network. Using the Mininet-WiFi platform, the performance of each controller is evaluated in terms of throughput, latency, jitter, and packet loss. Moreover, a multi-criteria evaluation is introduced and applied to provide a fair comparison between SDWNs. This study provides an appropriate configuration of SDWNs that is useful for network engineering and can be used for SDWNs performance optimization.

5G is the latest mobile communications standard that is spreading fast across the world. Recently defined requirements for 5G systems have led to higher applications’ requirements regarding data rates, lower requirements for latency, and higher efficiency regarding the spectrum usage. Universal Filtered Multi-Carrier (UFMC) is one new candidate modulation scheme for emergent Fifth Generation (5G) communication systems. This paper focuses on Universal Filtered Multi-Carrier (UFMC) design aspects in terms of Bit Error Rate (BER) performance in relation to the filter length used in subband filtering. Simulation results show that BER and CCDF performance varies for different filter lengths and modulation schemes. The main achievement of this work is that the results show that different Dolph–Chebyshev FIR filter lengths do not affect the BER performance both for the 64 and 256 QAM.

Multistage interconnection networks (MINs) provide critical communication resources between network components with an attractive cost/performance relation. In this paper, a novel architecture for a MIN is proposed. In contrast to other existing networks, this new architecture operates via wormhole routing using a multi-lane equivalent-weighted fair queuing system. Associating the lane storage with each physical channel for movement of the flits allows for high levels of packet flow and makes the system more robust. The resulting flit scheduling schema has been studied thoroughly, and the results are presented in this manuscript. In addition to performance metrics, additional factors such as complexity, cost and reliability are investigated. Since a basic aim of the design of MINs is to achieve a good data flow control mechanism, this proposal is an extremely effective and robust solution. The rationale behind this innovative scheme is to introduce a more efficient network technology, thus providing a better quality of service (i.e. streaming media vs. file transfer).

Summary: Constructing capable and scalable parallel computers or connecting contemporary networks efficiently makes multistage switching networks essential and significant devices. This is why they remain an interesting field of research and are being continually improved. This paper introduces a new idea—a new architecture—to ameliorate the behaviour of the networks' connection points. The proposed novel construction accommodates multiple internal paths and a fan‐out at the end. Via this study, basic features of this introduced fabric (such as cost, reliability, and performance measures) are presented in a quantitative manner. Moreover, some comparisons—especially in terms of complexity, cost, and reliability—with other similar modern constructions that also enclose multiple internal routes are shown. This study reveals that the proposed multistage system improves performance metrics, fault tolerance, and reliability and indicates that due to its properties, this innovative device can be used in the commercial sector.