PAPR Reduction in Universal Filtered Multicarrier Systems with Companding Transform

Abstract

Universal filtered multi carrier (UFMC) is an alternative waveform for both orthogonal frequency division multiplexing and filter bank multi carrier. High spectral efficiency is the attractive feature of 5G UFMC system. However, UFMC undergoes with high peak-to-average power ratio (PAPR), which affects the efficiency of power amplifier. Companding techniques are simple and proficient to reduce the PAPR of UFMC signals. In this paper, a linear nonsymmetrical companding transform (LNST), which reduces PAPR of UFMC signals without changing the average power of the companded signal, is proposed. In LNST scheme, the large and small amplitudes of the UFMC signal are companded with different scales depending on an inflexion point. Hence, more flexibility is available for choosing of companding parameters to get the optimal performance interms of PAPR, average power level and BER. Simulation results confirm that the LNST scheme offers better PAPR reduction and BER characteristics when compared to original UFMC signal and clipping technique. The netgain of the UFMC system with LNST companding is 3.5 dB. Also, the BER of the proposed LNST scheme is assessed for higher order modulations and it presents better BER characteristics when compared to original signal.