Abstract
Quantum key distribution constellation is the key to achieve global quantum networking. However, the networking feasibility of quantum constellation that combines satellite-to-ground accesses selection and inter-satellite routing is faced with a lack of research. In this paper, satellite-to-ground accesses selection is modeled as problems to find the longest paths in directed acyclic graphs. The inter-satellite routing is interpreted as problems to find a maximum flow in graph theory. As far as we know, the above problems are initially understood from the perspective of graph theory. Corresponding algorithms to solve the problems are provided. Although the classical discrete variable quantum key distribution protocol, i.e., BB84 protocol, is applied in simulation, the methods proposed in our paper can also be used to solve other secure key distributions. The simulation results of a low-Earth-orbit constellation scenario show that the Sun is the leading factor in restricting the networking. Due to the solar influence, inter-planar links block the network periodically and, thus, the inter-continental delivery of keys is restricted significantly.
Highlights
The communication security is extremely important in commerce, finance and government affairs
Quantum key distribution (QKD) [1] is a promising technology to protect communication security in times when the security of the encryption system based on mathematical complexity is imperiled under the quantum computing system
The simulations consist of a constellation with 9 orbital planes and 40 ground stations located in 40 different cities globally
Summary
The communication security is extremely important in commerce, finance and government affairs. The constellation consisting of low-Earth-orbit (LEO) satellites is the practical choice to build inter-continental quantum networks. By selecting the proper accesses for the quantum constellation, more keys can be distributed to each ground station. Wang et al [12] investigated the performance of a QKD constellation that consists of satellites in a single orbital plane, including the accesses selection algorithm, key re-distribution algorithm and relayed-key consumption. Wang et al [16] researched the routing algorithm and key resource allocation of QKD satellite networks. Both of their models to calculate the key rate and inter-satellite links are rough, as they did not take the finite-size effect and secure key distillation into consideration.
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