  This paper considers uplink multiple access (MA) transmissions, where the MA
technique is adaptively selected between Non Orthogonal Multiple Access (NOMA)
and Orthogonal Multiple Access (OMA). Two types of users, namely Internet of
Things (IoT) and enhanced mobile broadband (eMBB) coexist with different
metrics to be optimized, energy efficiency (EE) for IoT and spectral efficiency
(SE) for eMBB. The corresponding multi-objective power allocation problems
aiming at maximizing a weighted sum of EE and SE are solved for both NOMA and
OMA. Based on the identification of the best MA strategy, a clustering
algorithm is then proposed to maximize the multi-objective metric per cluster
as well as NOMA use. The proposed clustering, power allocation and MA selection
algorithm is shown to outperform other clustering solutions and non-adaptive MA
techniques.
