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Abstract
In recent research study, non-orthogonal multiple access (NOMA) has been shown to be one of the radio access technologies that is 5G compatible in the sense that it practically increases the spectral efficiency of system latency reduction. This work presents performance evaluation of multiple antenna non-orthogonal multiple access (NOMA) system in multiuser scenario. The objective is to analyse a multiple-antenna NOMA system in multiuser scenario. Mathematical equations that describe the dynamics and characteristics of multiple antenna NOMA downlink system were used to develop MATLAB models used to carry out the performance analysis via simulations. The simulations were evaluated in terms of two performance metrics namely, Bit Error Rate (BER) against Transmit power (dBm) and achievable sum rates. The results from the simulations conducted in terms of BER against Transmit power in dBm, revealed that the near user equipment (UE-1) has better performance (BER of 2.0e-06) than the far user equipment (UE-2) (of BER =.2.4e-05) at 40 dBm with distance of UE-2 from the base station (BS) equal to 500m. Further simulation by reducing the distance of the UE-2 to 300m showed that the BER of both users improves such that UE-1 has BER of 0, while for UE-2, it was 3e-06 at Transmit power of 40 dBm. The achievable sum rate curve of Multiple- Input Multiple -Output (MIMO) NOMA system revealed that it increases exponentially as the transmit power increases such that the outcome was a value of 20.75 bps/Hz at transmit power of 40 dBm. Further simulation of achievable sum rates of UE-1 and UE-2 indicated that the near user has a value of 18.75 bps/Hz as against 1.999 bps/Hz for the far user. This performance was achieved when the distance of the UE-2 equal to 500m. With the distance of UE-2 equal to 300m, the achievable sum rates of UE-1 and UE-2 were 18.75 bps/Hz and 2 bps/Hz respectively. Hence, with these results for different distances of UE-2 from the BS revealed that distance of user does not significantly influence achievable sum rate performance. In addition, performance of the MIMO-NOMA was compared with Multiple-Input Multiple-Output-Orthogonal Multiple Access (MIMO-OMA). Simulation results revealed that the MIMO-NOMA downlink system outperformed the MIMO-OMA in terms of achievable sum rate. In the case of comparison of users in both MIMO-NOMA and MIMO-OMA, the result of the analysis revealed that the user in MIMO-NOMA yielded better achievable sum rate than the user in MIMO-OMA. The system can be used for 5G network application. Key Words: Non-Orthogonal Multiple Access, 5G, Wireless Communication, Antenna, and Bit Error Rate