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Journal of Optical Communications and Networking

Cost-effective QKD protocol upgrading for metropolitan quantum optical networks

Mingxuan Guo, Yuan Cao, Jiali Zhu, Xingyu Zhou, Chunhui Zhang, Xiaosong Yu, Yongli Zhao, Jie Zhang, Qin Wang

Published Aug 16, 2023• 9 citations
Publisher

Abstract

Quantum key distribution (QKD) is a promising technology that can provide future-proof security. With the emergence of multiple advanced QKD protocols, the QKD protocol upgrading for a metropolitan quantum optical network (MQON) is critical for fulfilling the requirements of users for secret keys with a high security level. Conventionally, due to the lack of effective QKD protocol upgrading strategies for MQONs, massive amounts of resources have to be consumed during QKD protocol upgrading, resulting in high costs. In order to reduce the costs for practical implementation of QKD protocol upgrading, in this work, a new policy of QKD protocol upgrading is proposed, where the bypass technique is adopted to decouple multiple protocols from the linking patterns for efficient resource utilization. Moreover, we illustrate a multi-role QKD node structure for enabling the harmonious operation of multiple QKD protocols. A mixed integer linear programming (MILP) model and a novel divided-packet-based QKD protocol upgrading algorithm are designed to save costs by relying on flexible traffic management. We also propose a fixed-chain-based QKD protocol upgrading algorithm with fixed traffic management for achieving low costs. Simulation results indicate that the proposed heuristic algorithms are significantly more cost effective than the associated benchmark algorithms, while the MILP model can reduce the cost of protocol upgrading by 41% compared with the benchmark.

DOI
10.1364/jocn.496154

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Quantum key distribution (QKD) is a promising technology that can provide future-proof security. With the emergence of multiple advanced QKD protocols, the QKD protocol upgrading for a metropolitan quantum optical network (MQON) is critical for fulfilling the requirements of users for secret keys with a high security level. Conventionally, due to the lack of effective QKD protocol upgrading strategies for MQONs, massive amounts of resources have to be consumed during QKD protocol upgrading, resulting in high costs. In order to reduce the costs for practical implementation of QKD protocol upgrading, in this work, a new policy of QKD protocol upgrading is proposed, where the bypass technique is adopted to decouple multiple protocols from the linking patterns for efficient resource utilization. Moreover, we illustrate a multi-role QKD node structure for enabling the harmonious operation of multiple QKD protocols. A mixed integer linear programming (MILP) model and a novel divided-packet-based QKD protocol upgrading algorithm are designed to save costs by relying on flexible traffic management. We also propose a fixed-chain-based QKD protocol upgrading algorithm with fixed traffic management for achieving low costs. Simulation results indicate that the proposed heuristic algorithms are significantly more cost effective than the associated benchmark algorithms, while the MILP model can reduce the cost of protocol upgrading by 41% compared with the benchmark.
Time-sharing of Quantum Key Distribution (QKD) transceivers with the help of optical switches and a central Software-Defined Networking (SDN) controller is a promising technique to better amortize the large investments required to build a Quantum Key Distribution Network (QKDN). In this work, we investigate the implications of introducing Time-Division Multiplexing (TDM) in trusted-relay QKDNs at the wide-area network scale in terms of performance and cost-saving. To this end, we developed both a Mixed Integer Linear Programming (qTDM-MILP) model and a Heuristic Algorithm (qTDM-HA) to solve the allocation of QKD transceivers and network resources for a novel switched QKDN operating scheme: qTDM-QKDN. Our heuristic method provides a close-to-optimal resource planning for the offline problem that computes the minimum number of QKD transceivers and optical switch ports at each node, as well as the number of quantum channels on each link required to satisfy a target set of end-to-end secret-keyrate demands. Moreover, both the model and the heuristic provide the time fractions that each QKD transceiver needs to peer with each neighbor QKD transceiver. We compared our proposed model and heuristic algorithm for cost minimization with non-time sharing QKD transceivers (nTDM) as baseline. The results show that qTDM can achieve substantial cost-savings in the range of 10%–40% compared to nTDM. Furthermore, this work sheds light on the selection of the value for the working cycle T and its influence on network performance. • TDM optimizes QKD networks, enhancing efficiency and cost-effectiveness. • A MILP model and the qTDM-HA ease resource allocation in large-scale QKD networks. • The tools provide outstanding solutions from 10% to 40% in terms of cost-savings. • TDM minimizes the number of dedicated QKD transceivers by using shared ones wisely.
Quantum key distribution (QKD) can provide long-term security for numerous users. Currently, quantum networks are still in the early stages of small-scale deployment, most of which can only support a single QKD protocol (QKDP). However, with the advancement of various QKDPs, a single-protocol quantum network is no longer sufficient to meet the demands of multiple users, prompting the emergence of multi-protocol quantum networks. Nevertheless, the transition from a single-protocol to a multi-protocol quantum network still faces many challenging issues, such as key negotiation interruptions due to device initialization and channel calibration during protocol updating. To address the quantum key negotiation interruption problem, we propose a seamless key negotiation oriented multi-protocol updating algorithm in this work, which can fulfill the protocol updating requests of different users in quantum metropolitan networks. Furthermore, to better improve network performance while meeting diverse user demands, we propose four heuristic algorithms for optimal QKDP recommendation, focusing on their applications for multi-protocol updating in different types of typical networks. We perform the simulations with different QKDP recommendation algorithms to analyze the impact of the cache time of the key cache area on the key negotiation interruption probability and the time resource utilization. Simulation results demonstrate that the proposed algorithm can reduce the key negotiation interruption probability by 77.7% while increasing the time resource utilization by 15.3% compared to no key cache area.
Time-sharing of Quantum Key Distribution (QKD) transceivers with the help of optical switches and a central Software-Defined Networking (SDN) controller is a promising technique to better amortize the large investments required to build a Quantum Key Distribution Network (QKDN). In this work, we investigate the implications of introducing Time-Division Multiplexing (TDM) in trusted-relay QKDNs at the wide-area network scale in terms of performance and cost-saving. To this end, we developed both a Mixed Integer Linear Programming (qTDM-MILP) model and a Heuristic Algorithm (qTDM-HA) to solve the allocation of QKD transceivers and network resources for a novel switched QKDN operating scheme: qTDM-QKDN. Our heuristic method provides a close-to-optimal resource planning for the offline problem that computes the minimum number of QKD transceivers and optical switch ports at each node, as well as the number of quantum channels on each link required to satisfy a target set of end-to-end secret-keyrate demands. Moreover, both the model and the heuristic provide the time fractions that each QKD transceiver needs to peer with each neighbor QKD transceiver. We compared our proposed model and heuristic algorithm for cost minimization with non-time sharing QKD transceivers (nTDM) as baseline. The results show that qTDM can achieve substantial cost-savings in the range of 10%-40% compared to nTDM. Furthermore, this work sheds light on the selection of the value for the working cycle T and its influence on network performance.
Quantum key distribution (QKD) has become a promising option for transmitting sensitive data due to the increased maturity of QKD devices and the threat scalable quantum computers imposes on asymmetric public-key cryptosystems. By utilizing existing infrastructure, e.g., amplifier huts and dark fibers, the cost and complexity of deploying QKD networks (QKDNs) can be reduced. In this study, we develop a topology optimization algorithm that minimizes the cost of the QKDN deployment and maximizes the key capacity between any pair of nodes. We present three deployment upgrade strategies for facilitating the encryption of increasing throughput of QKD-secured optical transport networks and enabling a pay-as-you-grow approach. Comparing different strategies in a capacity-planning study allows operators to assess the scalability of deployments and upgrades. Depending on the availability requirements, our results compare the cost of protection measures. We confirm that adding trusted nodes is the most cost-efficient upgrading strategy based on our analysis.
Quantum key distribution (QKD) uses the laws of quantum mechanics to distribute secret keys with information-theoretic security. To realize QKD for secure communications among multiple distant users, fiber-based QKD networks can be deployed with today's available technologies. Incorporating QKD into existing wavelength-division multiplexing (WDM) network infrastructure provides a practical way to reduce the difficulty and cost of QKD networking. Nonetheless, the costs of QKD nodes and QKD links are still considered as the major barriers to long-distance QKD network deployment in practice. In this work, we study how to minimize the cost of deploying QKD-over-WDM backbone networks. We introduce a general architecture of QKD-over-WDM backbone networks. A novel cost-oriented model is defined to elaborate the cost-minimized problem, in which various QKD network components including QKD transceivers, QKD auxiliary equipment for QKD backbone nodes and trusted repeater nodes (TRNs), and QKD links are considered. The physical-layer parameters such as secret-key rate, physical distance, and the layout of TRNs are also incorporated in our defined model. We develop an integer linear programming (ILP) model and a novel cost-efficient QKD networking (CEQN) heuristic algorithm to address the cost-minimized problem. The extensive simulations indicate that our proposed approaches are effective in reducing the cost of deploying QKD-over-WDM backbone networks, where the designed CEQN algorithm is efficient to demonstrate similar to the ILP model. Finally, some open issues in future work are discussed, given that this work only presents an early highlevel analysis as opposed to a definitive detailed model.