Performance analysis of discrete wavelet transform for downlink non-orthogonal multiple access in 5G networks

Non-orthogonal multiple access (NOMA) has been considered a key technology to address the increasing traffic demands for fifth-generation (5G) cellular wireless communication networks and internet of things. The NOMA technique offers efficient bandwidth utilisation, low latency, and support for the massive connectivity of devices in 5G networks. In the conventional NOMA system, orthogonal frequency division multiplexing (OFDM) is used as a pulse-shaping technique that causes high peak to average power ratio (PAPR) due to the superposition of signals of multiple users after passing through inverse fast Fourier transform and spectral inefficiency due to the cyclic prefix insertion. Therefore, an alternate methodology using wavelet OFDM is proposed in this research work, as a pulse-shaping technique for NOMA-based communication systems to improve spectral efficiency and system capacity The main contribution of this study is the analysis of the bit error rate (BER) performance and the effect of carrier frequency offset on system performance of wavelet NOMA (W-NOMA) technique in 5G networks. The simulation results demonstrate that W-NOMA outperforms the conventional NOMA with reference to PAPR and BER.