Unitary space-time modulation using multiple antennas promises reliable communication at high transmission rates. The basic principles are well understood and certain criteria for designing good unitary constellations have been presented. However so far no general method to design good-performing constellation with large diversity product and diversity sum for any number of transmit antennas an...

SHAI is developing a software architecture for automated, distributed planning and coordination of constellations of satellites. This architecture allows large satellite constellations to manage themselves with minimal human oversight. SHAI is utilizing an integrated approach drawing upon a broad range of A! and non-Al techniques. Advanced planning and scheduling algorithms permit the system to...

Multiple antennas can greatly increase the data rate and reliability of a wireless communica-tion link in a fading environment. It is well-known that unitary matrices can be used to designdi erentially modulated space-time constellations. These constellations have a particularly e -cient description if they form a nite group under matrix multiplication. In this paper we willshow...

SaVi, a program for visualizing satellite orbits, movement, and coverage, is maintained at the University of Surrey. This tool has been used for research in academic papers, and by industry companies designing and intending to deploy satellite constellations. It has also proven useful for demonstrating aspects of satellite constellations and their geometry, coverage and movement for educational...

Recent work on lattices matched to the Rayleigh fading channel has shown how to construct good signal constellations with high spectral efficiency. In this paper we present a new family of lattice constellations, based on complex algebraic number fields, which have good performance on Rayleigh fading channels. Some of these lattices also present a reasonable packing density and thus may be used...

In 2012 it was forty years ago that the discovery of the first X-ray binary Centaurus X-3 became known. That same year it was discovered that apart from the High-Mass X-ray Binaries (HMXBs) there are also Low-Mass X-ray Binaries (LMXBs), and that Cygnus X-1 is most probably a black hole. By 1975 also the new class of Be/X-ray binaries was discovered. After this it took 28 years before ESAs INTE...

Large quadrature amplitude modulation (QAM) constellations are currently used in throughput efRcient high speed communication applications such as digital TV. For such large signal constellations, carrier phase synchronization is a crucial problem because for efficiency reasons the carrier acquisition must often be performed blindly, without the use of training or pilot sequences. The goal of t...

We consider Discrete Multitone (DMT, baseband OFDM) modulation and perform a detailed noise analysis which takes into account dependencies and power differences of real and imaginary part after the complex valued discrete Fourier transform (DFT). We show that for colored noise rotated rectangular symbol constellations are more appropriate than the common (quadratic) QAM symbol constellations wi...

Satellite missions demand ever greater connectivity, especially in the LEO regime. In this paper, we introduce new mega-constellation services space paradigm: show that mega-constellations, deployed to offer innovative Earth’s users, can provide excellent connectivity spacecrafts, too. First, characterise communication link between users and actual OneWeb Starlink constellations. A full set of ...

Non-coherent and Partially Coherent Space-Time Constellations