OFDM signal PAPR reduction method by pre-scrambling and clipping for frequency domain comb-type channel estimation case

This article presents a method of Peak-to-Average Power Ratio (PAPR) reduction of an Orthogonal Frequency Division Multiplexing (OFDM) signal. The proposed method is based on the following two approaches: bit-block pre-scrambling of the OFDM symbol, and clipping of the OFDM signal before transmission. Two different scrambling sequences are presented. The first one is a modified m-sequence with the least peak-factor, while the second one is a chaotic binary sequence generated by Logistic map and selected by peak-factor minimum criteria. Matlab computer simulation of OFDM system with 64 subcarriers with 4 pilot tones and frequency domain comb-type pilot channel estimation and the AWGN multipath channel is performed. Also, the stability of the pre-scrambled and clipped OFDM signal is examined. As a result, a bit error rate (BER) performance for various clipping levels obtained by the means of a computer simulation is presented. Besides, the efficiency of the joined pre-scrambling and clipping method is considered as well.