With the rise of 5G X-haul networks and emerging infrastructure segments, efficient multiplexing is essential for enabling secure quantum communication alongside classical data. In this work, we present a polarization-encoded Quantum Key Distribution (QKD) system deployed within the C-band over a live 5G network in Athens, demonstrating coexistence of QKD and 5G services on shared infrastructure. Our setup enables simultaneous transmission of 10 Gb/s classical data and QKD raw click rates of 4.3 kbps (22.6 km backhaul) and 51.9 kbps (2.2 km fronthaul). We propose a novel multiplexing approach using high-isolation, commercial-off- the-shelf (COTS) fiber filters and multiplexers, requiring no changes to existing infrastructure. The system achieves Quantum Bit Error Rates (QBER) below 1.5% and expected Secret Key Rates (SKR) of 650 bps and 11.3 kbps for backhaul and fronthaul, respectively, while maintaining uninterrupted 5G performance. This work offers a practical and scalable path for integrating QKD into future quantum-secured mobile networks.
With the rise of 5G X-haul networks and emerging infrastructure segments, efficient multiplexing is essential for enabling secure quantum communication alongside classical data. In this work, we present a polarization-encoded Quantum Key Distribution (QKD) system deployed within the C-band over a live 5G network in Athens, demonstrating coexistence of QKD and 5G services on shared infrastructure. Our setup enables simultaneous transmission of 10 Gb/s classical data and QKD raw click rates of 4.3 kbps (22.6 km backhaul) and 51.9 kbps (2.2 km fronthaul). We propose a novel multiplexing approach using high-isolation, commercial-off- the-shelf (COTS) fiber filters and multiplexers, requiring no changes to existing infrastructure. The system achieves Quantum Bit Error Rates (QBER) below 1.5% and expected Secret Key Rates (SKR) of 650 bps and 11.3 kbps for backhaul and fronthaul, respectively, while maintaining uninterrupted 5G performance. This work offers a practical and scalable path for integrating QKD into future quantum-secured mobile networks.
With the global deployment of 5G networks, the demand for high bandwidth and low latency has driven innovations in fronthaul architectures. However, traditional solutions face challenges related to security and signal interference. This paper proposes an innovative quantum-enhanced converged wireless-fiber 5G fronthaul system that integrates quantum key distribution (QKD) technology with a passive wavelength division multiplexing (WDM) architecture to achieve physical-layer secure communication. The system deploys the quantum transmitter (Alice) at the active antenna unit (AAU) side and the receiver (Bob) at the distribution unit (DU) side, leveraging the Heisenberg Uncertainty Principle, quantum measurement collapse theory, and the no-cloning theorem to detect eavesdropping attempts. Simulation results demonstrate the significant impact of noise detection probability, fiber loss, and transmission distance on both the secure key rate and quantum bit error rate (QBER). Key findings highlight the need to minimize fiber loss, reduce transmission distance, lower filter loss, decrease noise detection probability, and improve detection efficiency. These optimizations collectively enhance the secure key rate while reducing the QBER, thereby improving overall system reliability. Remarkably, this solution achieves these security enhancements without requiring large-scale modifications to existing infrastructure, offering a practical and cost-effective upgrade path for current 5G deployments while providing a future-proof foundation for emerging 6G networks. The architecture’s inherent scalability and compatibility make it particularly suitable for high-security applications, including government communications, financial transactions, and critical infrastructure protection—bridging the gap between theoretical quantum security and practical wireless network implementation.
The advancement of 6G networks demands high-capacity, ultra-low latency, and secure communication infrastructure. Traditional fronthaul solutions face significant challenges in meeting these demands due to increasing data traffic, network densification, and security vulnerabilities. To address these issues, this paper proposes an innovative 6G passive Wavelength Division Multiplexing (WDM) fronthaul architecture integrated with Quantum Key Distribution (QKD). By leveraging quantum cryptographic principles, our approach ensures unbreakable security and protects network transmissions from potential cyber threats and eavesdropping attacks. The proposed architecture effectively combines high-speed optical transmission with quantum-secured key exchange, optimizing network reliability and reducing security risks. Through comprehensive simulations, we evaluate key performance factors, including secure key rate (SKR), quantum bit error rate (QBER), detector efficiency, and quantum transmission loss. Results indicate that our architecture maintains high SKR with minimal QBER, even under challenging transmission conditions, ensuring robust quantum-secured communication. Additionally, the passive nature of WDM significantly reduces power consumption and maintenance costs, improving network sustainability. This research establishes a practical pathway for integrating quantum security into next-generation optical fronthaul networks, enabling highly secure, scalable, and efficient data transmission for future 6G applications, including autonomous vehicles, smart cities, and industrial IoT.
A research contribution focusing on the Quantum Key Distribution (QKD)-enabled solutions assisting in the security framework of an optical 5G fronthaul segment is presented. We thoroughly investigate the integration of a BB84-QKD link, operating at telecom band, delivering quantum keys for the Advanced Encryption Standard (AES)-256 encryption engines of a packetized fronthaul layer interconnecting multiple 5G terminal nodes. Secure Key Rate calculations are studied for both dedicated and shared fiber configurations to identify the attack surface of AES-encrypted data links in each deployment scenario. We also propose a converged fiber-wireless scenario, exploiting a mesh networking extension operated by mmWave wireless links. In addition to the quantum layer performance, emphasis is placed on the strict requirements of 5G-oriented optical edge segments, such as the latency and the availability of quantum keys. We find that for the dark fiber case, secret keys can be distilled at fiber lengths much longer than the maximum fiber fronthaul distance corresponding to the round-trip latency barrier, for both P2P and P2MP topologies. On the contrary, the inelastic Raman scattering makes the simultaneous transmission of quantum and classical signals much more challenging. To counteract the contamination of noise photons, a resilient classical/QKD coexistence scheme is adopted. Motivated by the recent advancements in quantum technology roadmap, our analysis aims to introduce the QKD blocks as a pillar of the quantum-safe security framework of the 5G/B5G-oriented fronthaul infrastructure.
With 5G networks enabling high-speed, low-latency communication, future 6G and quantum communications will require even higher data rates and enhanced security. Integrating quantum-safe technologies with classical systems through cofiber transmission enables the reuse of existing fiber infrastructure via multiplexing—reducing deployment costs and avoiding redundant construction. This approach offers a sustainable and environmentally friendly pathway for network evolution, positioning it as a key breakthrough in the development of secure 6G architecture.By leveraging Dense Wavelength Division Multiplexing (DWDM) over Optical Transport Networks (OTN), the system establishes an efficient bidirectional coordination framework between quantum and classical channels. The architecture incorporates multi-stage amplification, dispersion compensation, and an advanced optical-domain processing mechanism based on a "split-amplifycombine" scheme for quantum pulses. These features preserve signal integrity for both quantum and classical data while mitigating nonlinear effects. Additionally, the design includes a dual-mode key management system that meets the stringent requirements of 6G for high-speed responsiveness and large-scale concurrent quantum key distribution (QKD) through the dynamic coordination of real-time key generation and pre-stored keys. Crucially, the study analyzes Raman scattering noise in co-fiber transmission and reveals the distinct impacts of forward and backward Raman scattering on communication performance. Simulation results demonstrate that backward Raman scattering causes significantly greater degradation in secure key rate (SKR) and quantum bit error rate (QBER) than forward Raman scattering as transmission distance increases. Notably, forward Raman scattering yields better quantum communication performance metrics under ultra-long-distance transmission conditions.
As quantum computing threatens to compromise classical cryptographic systems, the need for future-proof, information-theoretically secure methods of communication has become critical. Quantum Key Distribution (QKD) leverages the fundamental principles of quantum mechanics to enable the secure generation and exchange of encryption keys, immune to computational attacks. This paper investigates the integration of QKD into telecom infrastructures to enable ultra-secure communication. We examine the performance of key QKD protocols, such as BB84 and E91, over fiber-optic and free-space channels, and simulate their deployment within realistic metropolitan network topologies. Results show that secure key rates of up to 10 kbps can be maintained over 50–80 km fiber links with Quantum Bit Error Rates (QBER) below 5%. The study also explores architecture models based on trusted relay nodes and WDM coexistence, highlighting practical deployment considerations. Our findings suggest that QKD is a viable enhancement for telecom security and a necessary foundation for long-term quantum-resilient communication systems.