A low complexity enhanced-NOMA scheme to reduce inter-user interference, BER and PAPR in 5G wireless systems

Abstract

Non-orthogonal multiple access (NOMA) has been recognized as an attractive technique to address the increasing traffic demands for heterogeneous wireless networks. The conventional fast Fourier transform NOMA (FFT-NOMA) system causes inter-user-interference (IUI), and high peak to average power ratio (PAPR) because of the superposition of multiple users on the same frequency subchannel. To reduce the PAPR, IUI, and bit error rate (BER) in a FFT-NOMA system, the enhanced-NOMA (E-NOMA) scheme is proposed that consists of a new low-complexity modified version of the conventional selected mapping (CSLM) cascaded with the Walsh–Hadamard transform (WHT). Simulation results demonstrate that the proposed E-NOMA scheme outperforms the FFT-NOMA with reference to PAPR and BER about 4.3 dB and 9.5 dB, respectively. Furthermore, at least 56% computational complexity reduction is achieved compared to an SLM-based NOMA method.