Heuristic Routing and Wavelength Allocation for Tidal Traffic in Quantum Secure Metropolitan Area Networks.

In quantum key distribution (QKD) metropolitan area networks (MANs), the tidal effect of traffic, which is caused by the imbalanced distribution of users, decreases network resource utilization and leads to an imbalanced distribution of quantum keys. Additionally, there is noise interference when both classical and quantum signals are transmitted together within the same optical fiber. To solve these problems while considering the specific requirements of the services, we propose heuristic routing and wavelength allocation algorithm. Firstly, the routing scheme based on Minimization of Network Load Standard Deviation (MNLSD) is applied to balance traffic, reduce blocking rate, and achieve the goal of balancing secure key rate of QKD system. Based on this, we design a wavelength allocation scheme by Priority Based on Noise Influence (PBNI), which is applied to the scenarios where quantum channels are fixed but classical services dynamically arrive. It achieves noise suppression by flexibly scheduling classical services. Simulation results shows that MNLSD can reduce the standard deviation of link load up to 83.9% and the blocking rate up to 20% compared to benchmark scheme. Additionally, when compared to benchmark scheme, PBNI can improve the secure key rate of QKD system up to 127.3%.