TMA-Based Beamforming for Next Generation Satellite Communication Applications

Low-Earth Orbit (LEO) satellite mega-constellations have attracted significant interest for their global network coverage and reduced latency with respect to their geostationary counterparts. LEO satellites are typically equipped with advanced antenna architectures, which allow spot-beam steering to specific areas within the field of view. With the aim to minimize on-board complexity, this paper studies the beam synthesis and steering using Time Modulated Arrays (TMA). By analyzing the properties of the on-off switching and their impact on the resulting beam footprint, this paper establishes the relationship between the pulse activation characteristics and the steering angle of the corresponding users in a downlink satellite-to-Earth transmission. The corresponding Signal-to-Noise Plus Interference Ratio (SINR) is derived and analyzed for multi-beam patterns with different inter-beam separations. We compare the performance of TMA-based LEO downlink transmission with conventional beamforming techniques, confirming the promising performance of TMA with reduced complexity. Finally, the TMA response is evaluated for practical channel estimation imperfections, demonstrating the degree of tolerance depending on the beam shape.