  Rate-splitting multiple access (RSMA) is a promising technique for downlink
multi-antenna communications owning to its capability of enhancing the system
performance in a wide range of network loads, user deployments and channel
state information at the transmitter (CSIT) inaccuracies. In this paper, we
investigate the achievable rate performance of RSMA in a multi-user
multiple-input single-output (MU-MISO) network where only slow-varying
statistical channel state information (CSI) is available at the transmitter.
RSMA-based statistical beamforming and the split of the common stream is
optimized with the objective of maximizing the minimum user rate subject to a
sum power budget of the transmitter. Two statistical CSIT scenarios are
investigated, namely the Rayleigh fading channels with only spatial
correlations known at the transmitter, and the uniform linear array (ULA)
deployment with only channel amplitudes and mean of phase known at the
transmitter. Numerical results demonstrate the explicit max min fairness (MMF)
rate gain of RSMA over space division multiple access (SDMA) in both scenarios.
Moreover, we demonstrate that RSMA is more robust to the inaccuracy of
statistical CSIT.
