An Efficient Piecewise Nonlinear Companding Transform for PAPR Reduction in UFMC Systems

Abstract

Universal Filtered Multi-Carrier (UFMC) is a potential multicarrier modulation system for future mobile communication. However, UFMC system also has the problem of high peak-to-average power ratio (PAPR), which might impact on power amplifiers leading to nonlinear distortion. In this paper, a new efficient piecewise nonlinear companding transform is proposed to reduce the PAPR in UFMC systems, while maintaining bit error rate (BER) performance and low out-of-band (OOB). In the proposed companding transform, the signals with amplitudes over a given peak amplitude is clipped for peak power reduction, and the signals with amplitudes close to the given peak amplitude is nonlinear transformed for power compensation, which decreases discontinuity point compared with linear transform. While the signals with small amplitudes remains unchange. By carefully adjusting transform parameters, more flexibility in the companding form and a better trade-off between PAPR reduction and BER performance can be achieved to satisfy various system requirements. Compared with other existing companding schemes, the simulation results show that the proposed technique can substantially offer the better performance of UFMC system in terms of PAPR reduction and BER performance.