The potential of non-orthogonal multiple access (NOMA) as a multiple access strategy for 5G and LTE upgrades has attracted much attention. In this study, we examine user pairing in NOMA strategy for multiple-input multiple-output (MIMO) users. The simulation results for near-near (N-N) and near-far (N-F) user pairing shames have been provided. The channel becomes time-selective after considering the node mobility situation. Furthermore, simulation curves demonstrate that adopting the user pairing approach reduces computing cost. The network's sum rate performance was further tested utilizing selection combining (SC) NOMA and time division for multiple access (TDMA). It is shown that when a user nearest to the base station is linked with the farthest user from the base station, the total sum rate dramatically increases. When the channel conditions between the two users are varied, the NOMA performs significantly better. The NOMA still surpasses TDMA in terms of sum rate when N-N and far-far (F-F) pairings are used, but the difference isn't significant. The SC-NOMA has a low performance when compared to TDMA. It was discovered that when the shape parameter is adjusted to two, the outage probability (OP) performance of three NOMA mobile users and a standard orthogonal multiple access (OMA) mobile user improved (multipath propagation scenario).