Integrating CE and Modified SLM to Reduce the PAPR of OFDM Systems

This study primarily integrated the techniques of selected mapping (SLM), constellation extension (CE), and Reed–Muller codes (RM codes) to construct an improved SLM technique termed RM-CE-SLM. A high peak-to-average power ratio (PAPR) is the primary disadvantage of orthogonal frequency division multiplexing (OFDM) systems. High PAPR not only reduces the performance of high-power amplifiers, but also increases the complexity of digital-to-analog converters. The RM-CE-SLM technique is primarily used to improve the high PAPR phenomenon of OFDM systems. The RM-CE-SLM technique initially uses RM codes to select the internal and external positions of constellation points in a 16 quadrature amplitude modulation (16-QAM) CE diagram. The technique also uses codeword elements in cyclic codes to produce the SLM scrambling sequence. The elements of a scrambling sequence are based on the codeword elements in cyclic codes, which determine whether to scramble the symbols after data are modulated. Symbol scrambling becomes the external constellation points in a 16-QAM CE diagram. The simulation results showed that PAPR performance in the RM-CES-SLM technique was superior to that of the traditional SLM technique. In addition, the proposed technique has an error correction capability, and does not require the transmission of additional side information.