Security is a major concern of digital society, and quantum key distribution (QKD) can contribute with an un-conditional secure mechanism for symmetric key distribution. Satellites have the opportunity to overcome the range limit of quantum communications based on fiber networks. This paper presents a method for performance evaluation of QKD based on satellites, exemplified with a case study that considers small satellites (CubeSats) in low Earth orbits (LEO), to illustrate a flexible configuration of the quantum range extender use case. To the best of the authors’ knowledge, this is the first time that a system evaluation derived from orbital propagation data is conducted while also considering QKD with a finite key statistics approach. This evaluation aims to match with the shortness and variability of visibility intervals typical of LEO orbits. The results confirm the feasibility of proposed case study and show the impact of relevant systems and orbital parameters in the key generation performance, such as system characteristics, uplink or downlink configuration, satellite altitude and orbital inclination. The estimated performance is then scaled to a year along with some sensitivity scenarios. The presented results may guide the design of future QKD satellite mission proposals.
Security is a major concern of digital society, and quantum key distribution (QKD) can contribute with an un-conditional secure mechanism for symmetric key distribution. Satellites have the opportunity to overcome the range limit of quantum communications based on fiber networks. This paper presents a method for performance evaluation of QKD based on satellites, exemplified with a case study that considers small satellites (CubeSats) in low Earth orbits (LEO), to illustrate a flexible configuration of the quantum range extender use case. To the best of the authors’ knowledge, this is the first time that a system evaluation derived from orbital propagation data is conducted while also considering QKD with a finite key statistics approach. This evaluation aims to match with the shortness and variability of visibility intervals typical of LEO orbits. The results confirm the feasibility of proposed case study and show the impact of relevant systems and orbital parameters in the key generation performance, such as system characteristics, uplink or downlink configuration, satellite altitude and orbital inclination. The estimated performance is then scaled to a year along with some sensitivity scenarios. The presented results may guide the design of future QKD satellite mission proposals.
Quantum Key Distribution (QKD) has emerged as a revolutionary technique for ensuring unconditional secure communication between two parties by exploiting the fundamental principles of quantum mechanics. At present, satellite based QKD is the only choice for distributing secure keys over larger distances, as fiber-based and terrestrial free-space systems have limited range. In this paper, the system engineering study and performance analysis for the satellite based QKD system is presented by carrying out the simulations for different orbits and orbital parameters. This work also presents the methodology to estimate the quantum keys generated for satellite to ground scenario across some of the suitable locations across Indian mainland. The orbital parameters of a LEO orbit are optimized to obtain a required accumulated key of more than 1 Mbits per day across all the ground stations. Two standard operating wavebands viz. 785 nm and 1550 nm, most suitable for quantum communication, are considered for both daylight and eclipse conditions and the difference in accesses, access gaps, access duration, key generation and key accumulation is obtained. A typical use-case scenario analysis for utilization of accumulated key over a year is also presented.
Optical quantum communication utilizing satellite platforms has the potential to extend the reach of quantum key distribution (QKD) from terrestrial limits of ∼200 km to global scales. We have developed a thorough numerical simulation using realistic simulated orbits and incorporating the effects of pointing error, diffraction, atmosphere and telescope design, to obtain estimates of the loss and background noise which a satellite-based system would experience. Combining with quantum optics simulations of sources and detection, we determine the length of secure key for QKD, as well as entanglement visibility and achievable distances for fundamental experiments. We analyse the performance of a low Earth orbit satellite for downlink and uplink scenarios of the quantum optical signals. We argue that the advantages of locating the quantum source on the ground justify a greater scientific interest in an uplink as compared to a downlink. An uplink with a ground transmitter of at least 25 cm diameter and a 30 cm receiver telescope on the satellite could be used to successfully perform QKD multiple times per week with either an entangled photon source or with a weak coherent pulse source, as well as perform long-distance Bell tests and quantum teleportation. Our model helps to resolve important design considerations such as operating wavelength, type and specifications of sources and detectors, telescope designs, specific orbits and ground station locations, in view of anticipated overall system performance.
This study aims at extending the concept of QKD to the optical free-space quantum communications domain. Moreover, the feasibility of a global satellite based quantum key distribution, in the low earth orbit (LEO) is investigated. Inline with this, three different link scenarios, including ground-to-ground, ground-to-satellite and satellite-to-satellite are considered. Moreover, system performance is analysed to show the sensitivity of the link to effect such as atmospheric attenuation, turbulence and detector noise. Generally, these factors are assumed to impair system performance by causing an overall increase in the systems quantum bit error rate (QBER), let alone limiting the communication bit rate and transmission distance of the link. The obtained results reveal the feasibility of satellite-based quantum key distribution in the LEO platform, a concept which could be potentially extended to geostationary earth orbit (GEO).
Quantum Key Distribution (QKD) offers a fundamentally secure method for key exchange, grounded in the principles of quantum mechanics rather than computational complexity. As advancements in quantum computing threaten classical cryptographic systems (such as RSA) QKD presents itself as a crucial technology for future secure communications. Among the primary challenges for global-scale QKD is the limited range of optical fiber channels, making satellite-based free-space optical links an attractive alternative. QKD presents unique constraints related to the short and unreliable communication windows, due to atmospheric conditions and the presence of sunlight, which makes the real time operation of QKD constellations almost impossible. Traditional configurations offering instantaneous global coverage, such as Walker constellations, are not necessary for QKD networks and other constellation designs may be explored. In this work, we present as an alternative a two-height, single orbital plane constellation, which facilitates regular and extended inter-satellite visibility, enabling the constellation to function as a virtual trusted node and increasing network capacity and flexibility. The main technical contribution is the development of a simulation tool designed to evaluate and optimize satellite QKD constellations. The simulator allows researchers and mission planners to assess key generation rates and overall system performance, helping to reduce the risks, costs, and uncertainties involved in satellite deployment. Our approach provides a powerful framework for advancing the development of scalable and efficient global QKD networks.
This paper presents a comprehensive feasibility analysis designed to model Low Earth Orbit (LEO) satellite-to-ground communications for Quantum Key Distribution (QKD), focusing on the 1550nm wavelength to facilitate the distribution of information through fiber segments. Discrete Variable Decoy State Polarization-based BB84 protocol is assumed whereas various detection setups and environmental conditions are simulated. Our analysis focuses on the receiver's design in terms of aperture and focal length to deliver a general framework by examining the coupling efficiency, a parameter strongly affecting the QKD satellite downlink. Through detailed simulation, we identify optimal configurations and operational parameters for various receiver designs, significantly enhancing the efficiency and reliability of satellite-to-ground QKD systems. The findings offer promising directions for extending the range of QKD systems, potentially revolutionizing secure communications by integrating satellite-transmitted quantum keys with terrestrial fiber networks. This study not only underscores the feasibility of advancing satellite-to-ground QKD technology but also lays the groundwork for future innovations in global quantum communications infrastructure.
With the rapid advancement of Low Earth Orbit (LEO) satellite constellations, ensuring the security of satellite-to-ground communication has become a critical concern. Traditional cryptographic techniques, while effective against classical attacks, face increasing threats from quantum computing. This paper proposes a quantum key secure transmission method tailored for LEO satellite-ground communication scenarios. The method integrates quantum key distribution (QKD) with dynamic channel estimation and orbital mobility prediction to support secure and low-latency key handshakes between satellites and ground stations. A hybrid encryption strategy is introduced, where QKD-generated keys are used to refresh symmetric session keys in real time, significantly enhancing resistance to eavesdropping and man-in-the-middle attacks. Simulation results demonstrate that the proposed method ensures stable key distribution under Doppler-shifted and intermittent link conditions, achieving improved secrecy capacity and resilience against quantum-level adversaries. This work provides a viable and scalable quantum-safe communication solution for future secure satellite networks.