With the growing complexity of quantum key distribution (QKD) network structures, aforehand topology design is of great significance to support a large-number of nodes over a large-spatial area. However, the exclusivity of quantum channels, the limitation of key generation capabilities, the variety of QKD protocols and the necessity of untrusted-relay selection, make the optimal topology design a very complicated task. In this research, a hybrid QKD network is studied for the first time from the perspective of topology, by analyzing the topological differences of various QKD protocols. In addition, to make full use of hybrid networking, an analytical model for optimal topology calculation is proposed, to reach the goal of best secure communication service by optimizing the deployment of various QKD devices and the selection of untrusted-relays under a given cost limit. Plentiful simulation results show that hybrid networking and untrusted-relay selection can bring great performance advantages, and then the universality and effectiveness of the proposed analytical model are verified.

中文翻译：

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混合量子密钥分发网络的拓扑优化

随着量子密钥分发（QKD）网络结构的日益复杂，预先拓扑设计对于支持大空间范围内的大量节点具有重要意义。然而，量子信道的排他性、密钥生成能力的限制、QKD 协议的多样性以及不可信中继选择的必要性，使得优化拓扑设计成为一项非常复杂的任务。本研究首次从拓扑的角度研究了混合QKD网络，分析了各种QKD协议的拓扑差异。此外，为了充分利用混合组网，提出了优化拓扑计算的解析模型，通过在给定的成本限制下优化各种 QKD 设备的部署和不可信中继的选择，实现最佳安全通信服务的目标。大量的仿真结果表明，混合组网和不可信中继选择可以带来很大的性能优势，从而验证了所提出的分析模型的通用性和有效性。