Comparative Evaluation of NOMA and OFDMA over Multipath Fading Rayleigh Channels in Downlink SISO System

Non orthogonal Multiple Access (NOMA) is the spectral and energy efficient multiple access technique utilised in 5G to overcome the limitations of Orthogonal Frequency Division Multiple Access (OFDMA). Analysis of NOMA performance has been undertaken by researchers and papers highlighting its efficacy have been published. Literature review reflects research gap on comparative performance evaluation in realistic channel with multipath fading losses. This performance evaluation is an important aspect that affects system design. In this research paper, novel model as per international standards for evaluation of comparative throughput performance of NOMA and OFDMA in multipath fading channels and losses has been proposed. The International Telecommunication Union specifications utilising frequency selective Rayleigh fading and path loss for urban, rural, fast moving and pedestrian conditions have been incorporated in system models for NOMA and OFDMA and the performance is compared. This paper suggests novel model for evaluation, analysis and simulation for comparative performance evaluation in Additive White Gaussian Noise (AWGN) and Rayleigh fading with path loss has been proposed and implemented for downlink Single–Input–Single–Output (SISO) system. Results show comparative throughput performance of NOMA and OFDMA system with improved throughput of NOMA in downlinks with Successive Interference Cancellation (SIC). Efficiency of NOMA system for different wireless channels has been simulated and evaluated. It is seen that system has improved performance upto 1.78 times with NOMA for downlink SISO with SIC system in AWGN and upto 2.538 times in multipath fading channels as compared to OFDMA.