  In this work, we investigate Block Diagonalization (BD) techniques for
multiuser multiple-antenna systems using rate-splitting (RS) multiple access.
In RS multiple access the messages of the users are split into a common part
and a private part in order to mitigate multiuser interference. We present the
system model for a RS multiple access system operating in a broadcast channel
scenario where the receivers are equipped with multiple antennas. We also
develop linear precoders based on BD for the RS multiple access systems along
with combining techniques, such as the min-max criterion and the maximum ratio
combining criterion, to enhance the common rate. Closed-form expressions to
describe the sum rate performance of the proposed scheme are also derived. The
performance of the system is evaluated via simulations considering imperfect
channel state information at the transmitter. The results show that the
proposed schemes outperform conventional linear precoding methods.
