PAPR Reduction in NC-OFDM/OQAM System using Nonlinear Companding Transform

Since the inherent higher Peak-to-Average Power Ratio (PAPR) in Non- Continous Orthogonal Frequency Division Multiplexing with Offset Quadrature Amplitude Modulation (NC-OFDM/OQAM) is higher than that of conventional NC-OFDM systems, a novel continuous and differentiable nonlinear companding scheme is investigated and analyzed when employing the conventional companding transforms. By making full use of the characteristic of the Gaussian-distributed original signals and employing a truncation to the distribution function of the original signals, the companded signals can be restricted in a specific region which consistent with the distribution of original signals. Therefore, the companded signals cannot only achieve an improved PAPR and Bit Error Ratio (BER) performance but also maintain the statistical characteristics of the original signals. Theoretical analysis and simulation results demonstrate that the proposed scheme substantially outperforms the conventional nonlinear companding schemes.