Joint DFT Precoding and Discrete Wavelet Transform in SC-FDMA NOMA System with Carrier Frequency Offset Compensation

Nonorthogonal multiple access (NOMA) is a promising multiple access (MA) technique for next-generation wireless systems with its capability to offer higher spectral efficiency, supporting massive network elements and low latency. Single-carrier frequency division multiple access (SC-FDMA) can be combined with NOMA systems to improve spectral efficiency and user capacity. This study proposes a transceiver structure for SC-FDMA based NOMA systems using discrete wavelet transform (DWT). The proposed transceiver structure employs joint discrete Fourier transform (DFT) precoding and DWT to obtain a higher bit error rate (BER) performance over conventional systems. The proposed scheme is referred to as a joint DFT precoded DWT SC-FDMA NOMA system that benefits through outstanding orthogonality and spectral containment characteristics of DWT, thereby improving the performance of the SC-FDMA NOMA system. Moreover, we have investigated the performance of the proposed system with variations in carrier frequency offset (CFO) to show the supremacy of the proposed SC‐FDMA NOMA System over multipath channels.