Quantum key distribution (QKD) has emerged as a pillar of secure communication based on the inherent principles of quantum mechanics. Widespread adoption of QKD, however, is hindered by major technical limitations in both fiber-optic and free-space channels. This work explores the integration of QKD with Dense wavelength division multiplexing (DWDM), free space optics (FSO), and radio frequency (RF) networks in a bid to address these challenges. It presents a thorough review of major theories, recent experimental breakthroughs, system architectures, and advantages of hybrid terrestrial and satellite-based systems. The discussion outlines current limitations, security issues, deployment methods, and advancements in standardization initiatives. Additionally, the chapter highlights future research trends, such as RF-assisted switching, trusted node architectures, and cross-technology synchronization. These developments are envisioned to form a crucial aspect of the global networked quantum internet.
Quantum key distribution (QKD) has emerged as a pillar of secure communication based on the inherent principles of quantum mechanics. Widespread adoption of QKD, however, is hindered by major technical limitations in both fiber-optic and free-space channels. This work explores the integration of QKD with Dense wavelength division multiplexing (DWDM), free space optics (FSO), and radio frequency (RF) networks in a bid to address these challenges. It presents a thorough review of major theories, recent experimental breakthroughs, system architectures, and advantages of hybrid terrestrial and satellite-based systems. The discussion outlines current limitations, security issues, deployment methods, and advancements in standardization initiatives. Additionally, the chapter highlights future research trends, such as RF-assisted switching, trusted node architectures, and cross-technology synchronization. These developments are envisioned to form a crucial aspect of the global networked quantum internet.
Due to the recent rapid growth of computing technologies, today's encrypted information based on classical computational complexities will soon no longer remain secure. Quantum cryptography, or quantum key distribution (QKD), relying on the physical laws of quantum mechanics, stands out as a more powerful cryptographic solution that enables the secret key to be shared securely over publicly unsecured communication channels in the presence of eavesdroppers. QKD can be possibly implemented over both optical fiber and free-space optical (FSO) links. Compared to optical fiber, FSO has the immediate advantage of flexibility and cost-effectiveness in terms of infrastructure deployment. More interestingly, recent advancements in satellite communications using FSO links promise the future of a global QKD network for highly secure applications. This paper reviews the development of QKD over FSO for both terrestrial and satellite channels, which highlights the most up-to-date QKD protocols. Owing to how the information is encoded, different QKD protocols are classified into technology-focused categories, where their properties are reviewed and compared. The feasibility of current QKD protocols is then investigated with respect to its specific application scenarios for terrestrial and satellite FSO links, equipped with results from both theoretical and experimental studies. Based on the latest free-space QKD achievements, novel perspectives for future developments and challenges to enhance the secrecy performance and reduce implementation cost are then summarized and comprehensively discussed. The potential combination of QKD and physical layer cryptography for the newly emerging wireless mobile communications networks involved with unmanned aerial vehicles (UAV) is also introduced.
Quantum Key Distribution (QKD) offers a revolutionary method for achieving information-theoretic security in communication systems by leveraging quantum mechanical principles. With foundational protocols like BB84 and newer innovations such as phase-matching and device-independent QKD, the field has rapidly progressed from theoretical constructs to real-world prototypes. Recent advancements in integrated photonics, high-speed key generation, and satellite-based systems suggest a transformative potential for global cybersecurity infrastructure. However, significant challenges remain in extending secure communication distances, ensuring practical implementation security, reducing cost and size of components, and integrating QKD into existing network architectures. This paper reviews the state-of-the-art in QKD, discusses emerging trends such as chip-based and layered QKD systems, evaluates satellite and free-space deployments, and examines the practical limitations and solutions for long-distance and high-rate secure communications. It concludes by highlighting future directions including standardization, hybrid classical-quantum infrastructures, and software-defined QKD networks.
As wireless networks become increasingly integral to modern communication infrastructures, the need for robust security mechanisms to protect sensitive information has never been more critical. Quantum Key Distribution (QKD) presents a revolutionary approach to secure communications by leveraging the principles of quantum mechanics to ensure the theoretical unbreakability of cryptographic keys. This study provides a comprehensive review of the current status of QKD technologies within the context of wireless networks, utilizing secondary data sources to analyze recent advancements, implementations, and challenges. The paper begins by outlining the fundamental principles of QKD and its superiority over classical cryptographic methods. It then examines recent developments in QKD protocols and their adaptability to wireless environments, highlighting successful case studies and experimental trials. Key challenges, including technological limitations, integration hurdles with existing network infrastructures, and cost considerations, are discussed in detail. The review also explores emerging trends and innovations, such as hybrid QKD systems and satellite-based implementations, which promise to expand the applicability and feasibility of QKD in wireless networks. Finally, the study delineates future prospects and potential research directions, emphasizing the need for interdisciplinary collaboration to overcome existing limitations and fully realize the potential of QKD in enhancing wireless network security.
With the rapid advancement of quantum computing, traditional cryptographic techniques are at risk of devolution, necessitating quantum-resilient alternatives for future communication networks. This systematic literature review evaluates the role of Quantum Key Distribution (QKD) in enhancing the security of sixth-generation (6G) wireless communications. Employing the PRISMA methodology, 48 peer-reviewed studies published between 2016 and May 2025 were identified and analyzed. The review addresses three key research questions: the identification of QKD protocols applicable to 6G, challenges in their integration, and proposed solutions for seamless deployment. Findings reveal that protocols such as BB84, E91, CV-QKD, and MDI-QKD, transmitted via optical fiber and satellite channels, offer promising security guarantees. This review concludes that while QKD can significantly strengthen 6G communications against quantum threats, further interdisciplinary efforts in hardware development, standardization, and pilot implementations are essential. The study offers valuable insights for researchers, engineers, and policymakers working toward secure, quantum-resistant future networks. The study follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology to ensure transparency, rigor, and reproducibility. A comprehensive search was conducted across major scientific databases, including IEEE Xplore, SpringerLink, ScienceDirect, and arXiv, using well-defined keywords and Boolean search strategies related to QKD, 6G networks, and quantum communication security. After removing duplicates and applying predefined inclusion and exclusion criteria, a total of 48 peer-reviewed studies published between 2016 and May 2025 were selected for detailed analysis. The selected literature was systematically classified to address three primary research questions: (i) identification of QKD protocols and technologies applicable to 6G networks, (ii) challenges hindering the integration of QKD into 6G architectures, and (iii) solutions and frameworks proposed to facilitate practical deployment. The findings reveal that prominent QKD protocols, including BB84, E91, Continuous-Variable QKD (CV-QKD), and Measurement-Device-Independent QKD (MDI-QKD), demonstrate strong potential for securing 6G communications when deployed over optical fiber and satellite-based channels. However, practical integration faces significant challenges such as scalability limitations, synchronization issues, quantum channel coexistence with classical networks, hardware complexity, and high deployment costs. The review further highlights emerging solutions that leverage Software-Defined Networking (SDN), Network Function Virtualization (NFV), blockchain-based key management, and hybrid classical-quantum security architectures to overcome these obstacles. Ongoing standardization efforts by organizations such as NIST, ETSI, and ITU-T are also identified as critical enablers for real-world adoption .
The emergence of the Quantum computing technologies is imposing greater threats on the existing cryptographic algorithms that rely heavily on the mathematical problems, creating a growing demand for quantum safe Communication. Even though Quantum Key Distribution (QKD) is a theoretically proven secure key exchange method against quantum attacks, it also faces several deployment challenges like scalability, cost, and interoperability limitations. A systematic review was conducted to examine the recent advancements in QKD technologies by analyzing the peer reviewed studies Published between 2021 to 2025 and classified according to protocol design, network architecture and deployment readiness. The review analyzed articles for a Comparison of the recent advancements in the field of Twin Field QKD, Continuous Variable QKD, Hybrid classical quantum networks and long-distance secure communication systems. Furthermore, the review also examined the Conjunction of QKD with the emerging security applications of 5G Networks, IOT environments, edge computing, fog Computing and Multimedia security systems. Despite of the significant technological advancements, the deployment of QKD is still under the constraints of scalability, lower key generation rates, cost of deployment, Synchronization issues, stability complexities, interoperability problems and standardization issues. Through a comprehensive evaluation of QKD protocols and network architectures, this study highlights the critical research gaps and provides future directions for the practical deployment of the QKD enabled secure communication networks.
Satellite-based quantum communications represent a critical advancement in the pursuit of secure, global-scale quantum networks. Leveraging the principles of quantum mechanics, these systems offer unparalleled security through Quantum Key Distribution (QKD) and other quantum communication protocols. This review provides a comprehensive overview of the current state of satellite-based quantum communications, focusing on the evolution from terrestrial to space-based systems. We explore the distinct advantages and challenges of discrete-variable (DV) and continuous-variable (CV) quantum communication technologies in the context of satellite deployments. The paper also discusses key milestones such as the successful implementation of quantum communication via the Micius satellite and outlines the primary challenges, including atmospheric turbulence and the development of quantum repeaters, that must be addressed to achieve a global quantum internet. This review aims to consolidate recent advancements in the field, providing insights and perspectives on the future directions and potential innovations that will drive the continued evolution of satellite-based quantum communications.