On companding techniques to mitigate PAPR in SC-FDMA systems

Abstract

Single Carrier Frequency Division Multiple Access (SC-FDMA) is being used successfully in the uplink communications of Long Term Evolution (LTE) standard. Owing to smaller envelope changes in SC-FDMA signal, it has a lower Peak to Average Power Ratio (PAPR) than Orthogonal Frequency Division Multiple Access (OFDMA) signal. But for higher order modulations, PAPR is still high and there is a requirement to mitigate PAPR in localised SC-FDMA systems. This paper discusses error function, exponential, rooting and logarithmic companding techniques that can be utilised to mitigate PAPR in SC-FDMA systems. Simulation results show that exponential companding technique provides better PAPR and Bit Error Rate (BER) performances at the cost of higher side lobes, and error function companding transform provides good PAPR and Power Spectral Density (PSD) performances at the cost of higher BER without increasing average signal power.