Two-level frame precoding with non-cooperative gateways

Abstract

This paper considers the pre-processing design to mitigate the multibeam interference in the downlink of a high-throughput satellite, with a common precoder for several users sharing the same frame, and limited adaptation capabilities on-board the satellite. Beams are grouped in clusters managed by different non-cooperative gateways. A two-level approach is performed, with an on-board beamforming network complemented by on-ground precoders. The former, designed with the SLNR (signal-to-leakage and noise ratio) criterion, mitigates the inter-cluster interference, whereas the latter fight the intra-cluster multiuser co-channel interference. Judicious user scheduling is also addressed to limit the impact of the multicasting and limited adaptation capabilities. Several two-level precoding designs can be obtained by setting accordingly the degree of cooperation and the frame adaptation, with an overall satisfactory performance with respect to the single-gateway benchmark. In particular, a sector-based solution with non-cooperative gateways presents a good trade-off between gateway autonomy and performance.