Distributed satellite antennas deliver broadband closer than expected
Modeling and Performance Evaluation of Distributed Satellite Antennas: Space Is Much Closer Than One Might Think
Information Theory
Summary
Satellites can work together in groups to act like one big antenna and provide internet directly to phones. The authors found that when satellites are close enough, the way radio waves spread out makes space communication different from usual assumptions. They show that treating wave signals as spherical, not flat planes, gives better predictions of internet speed and connection reliability. Their work also reveals when simpler models work well and when they fail, especially considering Earth’s shape and satellite orbits.
What this means in practice
- •For satellite network engineers: Design satellite arrays that optimize broadband throughput by accurately modeling radio wave propagation at near-field distances.
- •For wireless communication system designers: Improve direct-to-handset broadband links from satellites by selecting appropriate geometric and wave propagation models for large distributed antenna arrays.
Authors
Giacomo Bacci, Riccardo De Gaudenzi, Marco Luise, Luca Sanguinetti
Abstract
Distributed satellites can deliver broadband connectivity directly to commercial handsets. In the formation of arrays (FoA) architecture, cooperating satellites synthesize a large aperture whoseextent depends on their number, arrangement, and spacing, with intersatellite distances ranging from tens of meters to hundreds of kilometers. For representative S-band geostationary and low-Earth-orbit configurations, the Fraunhofer distance may exceed the nadir link range at spacings on the order of a hundred meters. Therefore, accurate assessment of FoA performance across satellite populations and spacings requires spherical-wave modeling for users in the radiative near field, below the formation's Fraunhofer distance. Planar models of satellite positions, array orientations, and user locations must also be assessed against spherical geometries accounting for orbital and Earth curvature. This paper combines these models to quantify how simplifying assumptions affect throughput and outage probability. Numerical results show that multi-antenna precoding based on a local plane-wave approximation within each satellite array closely matches the spherical-wave reference. A global plane-wave approximation can instead cause severe losses, including full outage. In the investigated scenarios, formation curvature has little impact, whereas neglecting Earth curvature overestimates low-Earth-orbit throughput. These findings clarify when geometric and propagation approximations remain reliable and demonstrate that, for large distributed antenna apertures, space is much closer than one might think.