  Distributed antenna system (DAS) has been deployed for over a decade. DAS has
advantages in capacity especially for the cell edge users, in both single-cell
and multi-cell environments. In this paper, non-orthogonal multiple access
(NOMA) is suggested in single-cell DAS to maximize user fairness and sumrate.
Two transmission strategies are considered: NOMA with single selection
transmission and NOMA with blanket transmission. In a two-user scenario, the
center base station (BS) uses NOMA to serve both users and the remote radio
units (RRUs) serve only the weak user based on the transmission scheme. The
signals sent from the RRUs are not considered as interference at both user
sides. At one side, the signals from the RRUs are used to detect the required
data and at the other side, the signals are used to perform successive
interference cancellation (SIC). The max-min performance is studied when
instantaneous channel gain information (CGI) or channel distribution
information (CDI) is known at the transmitter. A closed-form expression of the
upper bound is derived for the data rate of each user with only CDI. In
addition, the sum-rate is studied with a minimum rate constraint when
instantaneous CGI known at the transmitter. The results show that NOMA with
blanket transmission gives the best performance compared to other schemes;
conventional-NOMA, conventional single selection scheme and joint-transmission
(JT) NOMA. It is also shown that with less transmit power, NOMA with single
selection transmission gives better performance than conventional-NOMA.
