Performance analysis of hybrid PAPR reduction technique for LTE uplink communications

Long Term Evolution standard implemented Single Carrier Frequency Division Multiple Access (SC-FDMA) in the uplink communications due to its low peak to average power ratio (PAPR). But for higher order modulations, there is a need for further reduction of PAPR in SC-FDMA systems. There are numerous techniques to decrease PAPR, but clipping and companding techniques are very simple to implement without any side information. μ law companding provides good PAPR reduction but increases the average power of companded signal. In this paper, the distribution of SC-FDMA signal is approximated, and a companding technique is proposed to transform the approximated distribution into a uniform distribution, which reduces PAPR without increasing average power of the signal. For further improvement in PAPR, a hybrid technique is also proposed where the companded signal is clipped to a specific threshold value. Simulation results show that PAPR reduction achieved by the proposed companding technique is better than that of μ law companding with a slight degradation in bit error rate (BER) performance. The proposed companding technique with no decompanding operation has better BER performance when compared to that with approximated decompanding operation. The hybrid technique further reduces PAPR with similar BER performance as that of proposed companding technique by carefully choosing the clipping ratio.