  This paper considers the use of NOMA in multiuser MIMO systems in practical
scenarios where CSI is acquired through pilot signaling. A new NOMA scheme that
uses shared pilots is proposed. Achievable rate analysis is carried out for
different pilot signaling schemes including both uplink and downlink pilots.
The achievable rate performance of the proposed NOMA scheme with shared pilot
within each group is compared with the traditional orthogonal access scheme
with orthogonal pilots. Our proposed scheme is a generalization of the
orthogonal scheme, and can be reduced to the orthogonal scheme when appropriate
power allocation parameters are chosen. Numerical results show that when
downlink CSI is available at the users, our proposed NOMA scheme outperforms
orthogonal schemes. However with more groups of users present in the cell, it
is preferable to use multi-user beamforming in stead of NOMA.
