Performance Analysis of MIMO-NOMA and SISO-NOMA in Downlink Communication Systems

Non-Orthogonal Multiple Access (NOMA) is an interestingly new multi-user multiplexing communication technology which improves overall spectral efficiency for both LTE enhancement as well as 5G. Multiple Input Multiple Output (MIMO) offers excessive degrees of freedom to further improve the performance of NOMA. In this paper, work is done on an abstract idea of combining MIMO with downlink NOMA. For this, the performance of MIMO-NOMA technique has been analyzed in terms of both Bit Error Rate (BER) as well as sum rate with two-user MIMO-NOMA system. Simulation results shows the superiority of MIMO-NOMA over Single Input Single Output (SISO) NOMA in terms of both BER and sum rate. That is, 2X2 MIMO NOMA requires 4 dBm less power than SISO-NOMA, which further for 8x8 MIMO settings, again requires 10 dBm less power to achieve same BER. Similarly, for sum rate, when two users are at different distance from Base Station (BS), MIMO- NOMA performance is found superior than SISO-NOMA.