PAPR Performance for OFDM Signal Using Different Modulation Scheme by Selective Mapping and Partial Transmit Sequence

OFDM(Orthogonal Frequency Division Multiplexing) is a multicarrier modulation technique which has been widely used in modern wireless communications due to its high data rate, immunity to delay spread and frequency selective fading, high frequency spectral efficiency and other several advantages. Besides these benefits one of the main disadvantages is the PAPR problem. High PAPR will increase the system complexity and restrict the system performance. Two powerful and distortionless peak power reduction schemes for OFDM are compared in this paper. One investigated technique is selected mapping (SLM) where the actual transmit signal is selected from a set of signals and the second scheme utilizes phase rotated partial transmit Sequences (PTS) to construct the transmit signal. Both approaches are very flexible as they do not impose any restriction on the modulation scheme applied in the subcarriers or on their number. In addition, SLM algorithm is more suitable if the system can tolerate more redundant information; otherwise, PTS algorithm is more suitable when complexity becomes the first important factor. The simulation compared in this paper using BPSK and QPSK modulated OFDM signals and results shows that PTS perform better than SLM and the probability of high PAPR with increasing the number of sub-blocks in PTS technique decreases obviously, compared to the original OFDM signal.