  This letter considers a legacy massive multiple-input multiple-output (MIMO)
network, in which spatial beams have been preconfigured for near-field users,
and proposes to use the non-orthogonal multiple access (NOMA) principle to
serve additional far-field users by exploiting the spatial beams preconfigured
for the legacy near-field users. Our results reveal that the coexistence
between near-field and far-field communications can be effectively supported
via NOMA, and that the performance of NOMA-assisted massive MIMO can be
efficiently improved by increasing the number of antennas at the base station.
