A Systematic Literature Review: Quantum Key Distribution Networks: Challenges and Future Research Issues in Security

Abstract

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 .