SDR-Based Store & Forward Repeater PTToC Using QKD

The rapid evolution of Software-Defined Radio (SDR) technology, coupled with advancements in quantum computing, has significantly enhanced contemporary communication systems. This paper presents a novel Store & Forward Repeater system for Push-to-Talk over Cellular (PTToC), integrating SDR with quantum technologies to enhance security and performance. Traditional repeaters encounter limitations in security, latency, and data integrity. Our system leverages SDR’s flexibility and reconfigurability, enabling dynamic adjustments in frequency and modulation to optimize communication between distant nodes in mobile networks. The system incorporates Quantum Key Distribution (QKD) for secure data transmission, ensuring that any interception attempts are detected, thereby providing theoretically unbreakable encryption. The Store & Forward Repeater stores messages when the destination is unreachable and forwards them securely once reconnected, minimizing data loss. Our testing demonstrated substantial improvements in latency (up to 70% reduction), error rate, and data security over conventional PTToC systems. We also provide a comprehensive comparison with conventional communication systems, highlighting the advantages of integrating quantum cryptography with SDR. Numerical analysis underscores the efficiency gains achieved through QKD over traditional encryption methods. Finally, we discuss future research directions, including quantum-assisted modulation schemes and the integration of 5G networks to further enhance communication in mission-critical applications. This work establishes the groundwork for scalable, secure communication systems with applications in public safety, military, and emergency response scenarios.