Performance Analysis of OSTBC in NOMA Assisted Downlink System with SIC Errors

Abstract

This paper investigates the error performance of the orthogonal space-time block coding (OSTBC) in non-orthogonal multiple access (NOMA) assisted downlink system in the presence of successive interference cancellation (SIC) errors. In the proposed system model, the base station communicates with multiple users to exploit the benefits of OSTBC in NOMA, like transmit diversity gain and low complexity. The system performance of the proposed OSTBC-NOMA system is analyzed in terms of the average symbol error rate (ASER) over the Rayleigh fading channel model. Further, in order to get a better insight to the system performance, the analysis is conducted over a high SNR regime to obtain diversity order and asymptotic ASER. The analytical results corroborated with Monte-Carlo simulations illustrate that the proposed OSTBC-NOMA system outperforms the conventional NOMA system over different combinations of the modulation scheme. Also, the power allocation coefficient's impact on the system performance is numerically analyzed.