Nebula Public Library

Development of deep-space optical communication systems (DOCS) poses a number of technical challenges as compared to conventional radio-frequency links. The higher energy of a single quantum (a photon) at the optical carrier frequency implies the need for dedicated modulation formats and receiver designs. The current technical standard for efficient DOCS is pulse position modulation (PPM) format combined with direct detection (DD) which for photon-starved links is implemented as photon counting.

In this project, the University of Luxembourg studied and evaluated a new concept of connecting space missions via space internet providers. The system requirements, necessary adaptations, and possible limitations are provided and discussed. Three types of space internet provider were studied and evaluated: Starlink, OneWeb and O3b mPOWER.

Commonly used classical cryptographic protocols, such as the RSA-protocol, rely on the hardness of computational problems. With the advent of quantum computing (QC), the hardness assumptions of these problems is nullified, since they can be solved efficiently on a QC. On the other hand, the security of Quantum key distribution (QKD) rests upon the very laws of physics and guarantees information-theoretic security, which not only enables tap-proof communication at present, but also prevents any future technology to crack encrypted messages.

The Doherty concept has proven to be a very effective technique for designing amplifiers, which maintain a high efficiency over a wide range of operating conditions. This technique is extensively used in terrestrial applications like base stations where power efficiency is getting more and more attention. Power efficiency is also of concern for space and the Doherty concept could certainly help in designing more efficient PAs. Ka-band is now being considered for mobile services that could offer very high capacity as compared to the existing ones at L-band.