PAPR Reduction in OFDM Signal by Combining Partial Transmit Sequences with Precoding Matrix

Abstract

An orthogonal frequency division multiplexing (OFDM) signal has the drawback of a high peak-to-average power ratio (PAPR). A precoding method is proposed for PAPR reduction. In this method, a low PAPR signal is generated through multiplication by a matrix generated from a certain sequence and data symbol vector. The PAPR reduction achieved by this method is constant even when we use another matrix generated by a different parameter. The partial transmit sequences (PTS) method is another PAPR reduction method. In the PTS method, subcarriers that constitute an OFDM signal are partitioned into clusters. Then, the time-domain signals of each cluster are individually given phase rotations, and we select the OFDM signal with the lowest PAPR. This method does not cause a non-linear distortion because of linear processing. Numerous clusters and phase rotations are required, and the calculation burden becomes enormous to increase the PAPR reduction. In this paper, we show how both methods can be combined for the purpose of further reducing the PAPR. This paper shows that the PAPR reduction of the proposed method is better than that of the PTS or precoding methods separately. We also show that the proposed method can increase the PAPR reduction by increasing the number of candidate signals, as in the PTS method. Moreover, the proposed method can greatly reduce the number of candidate signals needed to achieve the same reduction.