To develop a realistic transmission scenario for downlink NOMA. 5.3 RELATED LITERATURE REVIEW Enormous numbers of researchers have demonstrated that NOMA systems can fulfill the requirements of fifth generation (5G). For example, the PD-NOMA was analyzed when transmitting over a fading channel in [4], where it was shown that NOMA can increase spectral efficiency significantly when compared with OMA. In [3], the researchers used a SIC receiver in a downlink-NOMA system, based on a projected future enhancement in device processing capabilities. They show that the downlink NOMA with the use of SIC operates well and improves cell-edge user throughput and overall capacity, based on system-level analyses [3]. Furthermore, the progress of NOMA is surveyed in [5] by the authors in 5G systems. The authors reviewed user fairness, power allocation techniques, capacity Non-Orthogonal Multiple Access Transmission analysis and the user pairing method in NOMA. In addition, the authors identified the operationalization of NOMA with different methods of communication for example space time coding, cooperative communication, beam foaming, MIMO, and network coding. In [6] the researchers, did comparison research of OMA and NOMA and found that a hybrid OMA/NOMA methodology could be a helpful solution for modern wireless cellular communications. Research in allocating power-efficient resources for multi- carrier (MC) NOMA was also undertaken in [7] with the goal of lowering total power usage. The study advocated low-complexity scheduling and sub-optimal power allocation for users. An overview of promising modulation scheme-aided NOMA is presented in [8], where the spectral efficiency, out-of-band leakage, and BER performances were examined. While in [9] a power allocation-aided beamforming is proposed for a downlink NOMA scenario, where a significant power reduction was exhibited, when compared to OMA systems. In [10], the author investigated beamforming to decrease the transmitted power for the downlink 2-user MISO based NOMA system