  In this paper, we discuss a non-orthogonal multiple access (NOMA) scheme to
exploit a high diversity gain using repetition, namely repetition-based NOMA.
Unlike conventional power-domain NOMA, all the users can have the same transmit
power, but different number of repetitions. Thanks to a high diversity gain, a
low outage probability can be achieved without instantaneous channel state
information (CSI) feedback for power allocation. A closed-form expression for
an upper-bound on the outage probability is derived so that the values of key
parameters can be decided to maintain the outage probability below a target
value. We also consider the average error probability for finite-length codes.
Simulation results are compared with the derived bounds and it is shown that
the bounds are reasonably tight and can be used to decide key parameters (e.g.,
code rates) to guarantee target error probabilities.
