arXiv subjects

Konstantinos Katzis

Publications and source records attributed to Konstantinos Katzis.

4 recordsLinked to original sources

arXiv2026

A Reconfigurable Multilayer Quantum Key Distribution Network over Existing Metropolitan Fibre

Scaling quantum networks requires architectures extending end-to-end service reachability despite constrained fibre and equipment. Critically, in brownfield deployments, the quantum network must be engineered around classical telecommunications infrastructure and the operating capabilities of quantum key distribution (QKD) technology. To address this, we demonstrate a seven-node, multilayer QKD network deployed over existing metropolitan fibre. The implementation compares spectral management techniques to accommodate inherited constraints across its layers. It combines a trusted-node ring with a three-node subnetwork interconnected through reconfigurable optical switching, extending physical connectivity and service reachability without an additional transmitter. A meshed key management layer maps endpoint requests onto trusted-relay paths and supplies Layer 1, Layer 3, and one-time-pad applications. Over 73 days, eight link configurations generated 119.4 Gbit of secret key material with 99.1% link availability. Randomised end-to-end requests revealed indirect cross-layer coupling between key consumption, stored-key state and quantum-layer reconfiguration, demonstrating resource sharing through reconfigurability, spectral multiplexing and logical key-management abstraction.

quant-ph↗

arXiv2025

Multi-node quantum key distribution network using existing underground optical fibre infrastructure

Quantum key distribution (QKD) offers unconditional information security by allowing two distant users to establish a common encryption key resilient to hacking. Resultingly, QKD networks interconnecting critical infrastructure and enabling the secure exchange of classified information, can provide a solution to the increasing number of successful cyberattacks. To efficiently deploy quantum networks, the technology must be integrated over existing communication infrastructure, such as optical fibre links. Yet, QKD poses stringent requirements on the conditions of the network over which it is deployed. This work demonstrates the first quantum communication network in Cyprus via the deployment of a multi-node quantum network, exploiting existing commercial underground optical fibre. The network employs bidirectional occupation of fibres and wavelength multiplexing in a ring architecture to achieve, with minimal use of dark fibres, high-rate QKD. Results obtained reveal consistent key generation rates across all nodes, confirming reliable operation in a real-world environment. This deployment highlights the feasibility of leveraging existing telecom infrastructure for quantum-secured communication, marking a significant step toward scalable and cost-effective quantum networks suited for critical applications.

quant-ph↗

arXiv2018

Resilience of airborne networks

Networked flying platforms can be used to provide cellular coverage and capacity. Given that 5G and beyond networks are expected to be always available and highly reliable, resilience and reliability of these networks must be investigated. This paper introduces the specific features of airborne networks that influence their resilience. We then discuss how machine learning and blockchain technologies can enhance the resilience of networked flying platforms.

eess.SP↗

arXiv2017

A Novel Airborne Self-organising Architecture for 5G+ Networks

Network Flying Platforms (NFPs) such as unmanned aerial vehicles, unmanned balloons or drones flying at low/medium/high altitude can be employed to enhance network coverage and capacity by deploying a swarm of flying platforms that implement novel radio resource management techniques. In this paper, we propose a novel layered architecture where NFPs, of various types and flying at low/medium/high layers in a swarm of flying platforms, are considered as an integrated part of the future cellular networks to inject additional capacity and expand the coverage for exceptional scenarios (sports events, concerts, etc.) and hard-to-reach areas (rural or sparsely populated areas). Successful roll-out of the proposed architecture depends on several factors including, but are not limited to: network optimisation for NFP placement and association, safety operations of NFP for network/equipment security, and reliability for NFP transport and control/signaling mechanisms. In this work, we formulate the optimum placement of NFP at a Lower Layer (LL) by exploiting the airborne Self-organising Network (SON) features. Our initial simulations show the NFP-LL can serve more User Equipment (UE)s using this placement technique.

cs.NI↗