# Satellite constellations for trusted node QKD networks

## TL;DR

This paper proposes a satellite constellation model for large-scale, on-demand quantum key distribution networks that enable secure communication between any two ground stations with low latency, using trusted-node and inter-satellite QKD links.

## Contribution

It introduces a novel constellation architecture combining low earth orbit and geostationary satellites for scalable, trusted-node quantum key distribution networks.

## Key findings

- Effective key buffering with trusted satellites.
- Feasibility of regional and global QKD networks.
- Potential of inter-satellite links for key balancing.

## Abstract

Quantum key distribution from satellites becomes particularly valuable when it can be used on a large network and on-demand to provide a symmetric encryption key to any two nodes. A constellation model is described which enables QKD-derived encryption keys to be established between any two ground stations with low latency. This is achieved through the use of low earth orbit, trusted-node QKD satellites which create a buffer of keys with the ground stations they pass over, and geostationary relay satellites to transfer secure combinations of the keys to the ground stations. Regional and global network models are considered and the use of inter-satellite QKD links for balancing keys is assessed.