  This paper studies the precoder design problem of achieving max-min fairness
(MMF) amongst users in multigateway multibeam satellite communication systems
with feeder link interference. We propose a beamforming strategy based on a
newly introduced transmission scheme known as rate-splitting multiple access
(RSMA). RSMA relies on multi-antenna rate-splitting at the transmitter and
successive interference cancellation (SIC) at the receivers, such that the
intended message for a user is split into a common part and a private part and
the interference is partially decoded and partially treated as noise. In this
paper, we formulate the MMF problem subject to per-antenna power constraints at
the satellite for the system with imperfect channel state information at the
transmitter (CSIT). We also consider the case of two-stage precoding which is
assisted by on-board processing (OBP) at the satellite. Numerical results
obtained through simulations for RSMA and the conventional linear precoding
method are compared. When RSMA is used, MMF rate gain is promised and this gain
increases when OBP is used. RSMA is proven to be promising for multigateway
multibeam satellite systems whereby there are various practical challenges such
as feeder link interference, CSIT uncertainty, per-antenna power constraints,
uneven user distribution per beam and frame-based processing.
