System Engineering Methodology for Satellite based QKD Architecture

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.