Non-Orthogonal Multiple Access (NOMA) is considered one of the promising radio access technologies that support 5G because it reduces latency and increases system’s spectral efficiency. This work presents performance enhancement of non-orthogonal multiple access (NOMA) network for 5G network application. A model for multiuser NOMA system was developed. With the developed model, downlink communication between a Base Station (BS) and 3 users located at different locations tagged far, mid, and near was simulated in MATLAB environment. The system performance was evaluated with respect to Bit Error Rate (BER), outage probability, and achievable sum rate against Signal to Noise Ratio (SNR) in dB, including Energy Efficiency (EE) against Spectral Efficiency (SE). When the users (UE-1, UE-2, and UE-3) were located at distances 100, 60, and 40 m from the BS, the BER simulated output waveforms of the system revealed that the nearest user (with user equipment, UE-3) had the best quality of signal reception in terms of BER with values: 0.00022 when SNR was 70 dB, 0.000021 when was 80 dB, and 0.0000019 when SNR was 90 dB  while  the farthest and mid user (UE-1 and UE-2) had BER of (0.00056, 0.000083, and 0.0000095) and (0.00042, 0.000038, and 0.0000038) according to order of the SNR, respectively. Generally, from the analysis, the user (UE-1) achieved the least BER in all cases and it is considered the weakest users. Also, user (UE-3) achieved the best BER and it was regarded as the strongest user.

Keywords: Multiple access, Bit error rate, NOMA, Spectral efficiency, 5G network.