Closed-Form BER Expression for Fourier and Wavelet Transform-Based Pulse-Shaped Data in Downlink NOMA

The non-orthogonal multiple access (NOMA) technique is a strong candidate for 5G cellular networks that enable greater multiuser capacity and user fairness through multiplexing in the power domain. The user data are pulse-shaped using the orthogonal frequency-division multiplexing (OFDM) technique based on the fast Fourier transform (FFT) for conventional NOMA. We propose a discrete wavelet transform-based pulse shaping technique for NOMA. We present a closed-form expression of the bit error rate (BER) for FFT-NOMA as well as wavelet-based NOMA (WNOMA) systems. The theoretical and simulation BER results show that WNOMA outperforms FFT-NOMA in additive white Gaussian noise.