Novel Efficient Multiwavelet-Based Modulation for Downlink NOMA Systems

A new modulation scheme using multiwavelets for downlink non-orthogonal multiple-access (NOMA) transceivers is presented in this work. Multiwavelets leading to remarkable spectral diversity are exploited to modulate/demodulate the superimposed multi-user signals in downlink NOMA systems, where the discrete multiwavelet transform and the inverse discrete multiwavelet transform are invoked in the new demodulator of the user equipment and the new modulator of the base station, respectively. The performance evaluation and the computational-complexity analysis of our proposed new NOMA scheme are also conducted. Simulation results demonstrate that the proposed new scheme can significantly increase the system capacity while dramatically suppressing the peak-to-average-power ratio (PAPR) compared to the conventional OFDM-based NOMA approach. Meanwhile, our new scheme can achieve the same system capacity as the scalar-wavelet-based NOMA approach but with a lower PAPR at little extra cost of computational-complexity. All of these three aforementioned NOMA schemes can result in the identical bit-error-rate under the same signal-to-noise ratio condition.