Traffic-Aware Trusted Node Placement and Resource Allocation in Multi-Band EONs Secured With QKD

Quantum key distribution (QKD) is considered as a promising solution for secure communications. Nevertheless, challenges such as the elevated cost of dark-fibers used for QKD, quantum transceivers (Q-TRx), and security issues with QKD trusted nodes impede its widespread deployment. This paper explores a multi-band elastic optical network (MB-EON) for implementing QKD on the existing fiber infrastructure, augmenting network capacity without the need for new fiber installations. The careful transmission of classical and quantum channels in MB-EON necessitates impairment-aware algorithms to shield quantum channels from potential disruptions caused by classical channels. To tackle this, we conduct an in-depth analysis of various noise sources to pinpoint the optimal key transfer scenario. Our study further includes calculations for the upper bound of the public interaction channel (PICh) bit rate in the BB84-Decoy protocol and the secret key rate (SKR). Furthermore, a time division multiplexing technique is proposed to allocate bit-rate of each Q-TRx and PICh-TRx among received demands and grooming them as a one connection. Furthermore, we delve into the QKD trusted node placement method as a robust solution for long-distance QKD, effectively minimizing Q-TRx usage and selecting less QKD trusted nodes to bolster network security by proposing the hot-links algorithm (HLA). Finally, three routing, modulation format, spectrum, and time slot assignment (RMSTA) algorithms are proposed and compared. The simulation results reveal that the proposed HLA trusted node placement method with flexible routing of classical channels and QKD channels demonstrates significant improvements in key transfer efficiency, network security, and blocking probability compared to the fixed-distance trusted node placement with joint routing of CChs and QKD channels.