Design Trade-Off Analysis of Precoding Multi-Beam Satellite Communication Systems

To cope with the ever increasing demand for larger throughput, Satellite Communications (SatCom) systems are evolving towards Very High Throughput Satellites (VHTS). These are mainly characterised by an increased number of beams, 4-colour frequency reuse, and adaptive antennas. Aiming at further improving the system throughput by means of aggressive frequency reuse schemes, namely full frequency reuse, linear precoding techniques have already proven the benefits for both terrestrial and satellite HTS systems. However, precoding has never been considered for implementation with adaptive antennas that are capable of varying the radiation patterns on-board the satellite and, thus, increasing or reducing the overlap of adjacent beams signals at beam edge. In this paper, we provide a system design trade-off analysis for MMSE precoding with adaptive antennas in terms of average spectral efficiency and outage probability. The proposed analysis shows that significant gains can be considered when increasing/reducing the overlap of signals from adjacent beams at beam edge. Moreover, thanks to adaptive antennas, a non-negligible benefit can also be achieved in terms of reduced transmission power on-board the satellite when more directive patterns are generated.