  This paper compares the sum rates and rate regions achieved by power-domain
NOMA (non-orthogonal multiple access) and standard massive MIMO (multiple-input
multiple-output) techniques. We prove analytically that massive MIMO always
outperforms NOMA in i.i.d.~Rayleigh fading channels, if a sufficient number of
antennas are used at the base stations. The simulation results show that the
crossing point occurs already when having 20-30 antennas, which is far less
than what is considered for the next generation cellular networks.
