Performance Enhancement of Multicarrier NOMA for 5G NR System

The Multiple Access (MA) techniques in wireless systems are either Orthogonal MA (OMA) or Nonorthogonal MA (NOMA). OMA suffers from less spectral efficiency (SE), while NOMA is struck by inter-user interference. Due to the diversity of applications in Fifth Generation (5G) and Beyond 5G (B5G) communications, the trade-off between complexity and performance in Multicarrier NOMA (MC-NOMA) takes a lot of attention. In this paper, a combination technique between orthogonal frequency division multiplexing (OFDM) and NOMA employing 5G new radio (NR) flexible numerology to achieve an enhancement in the MC-NOMA performance is proposed. One base station (BS) and three downlink users are considered. The results show a considerable enhancement in achievable sum rate and users' data rates as compared with OMA and NOMA. Although the bit error rate (BER) of the proposed system is higher than that of OMA, it provides a reasonable enhancement as compared with NOMA. A mathematical model of BER performance for a two-user scenario is expressed too. The model showed its correctness in a comparison between system analysis and simulation. The proposed system reaches a bit rate of 400 Mbps at a 5dB signal-to-noise ratio (SNR) value, whereas OMA and NOMA provide about 240 Mbps at a 5dB SNR value when they tested over 32MHz carrier bandwidth.