PAPR Reduction and Data Security Improvement for OFDM Technique using Chaos System

Higher value of Peak to Average Power Ratio (PAPR) in wireless Orthogonal Frequency Division Multiplexing (OFDM) systems makes low power efficiency, several degradation of performance in the transmitting power amplifier, and increases complexity of converters. So, it is important to decrease PAPR to avoid these problems. This paper presents a proposed algorithm to decrease PAPR by generating several Aperiodic PseudoRandom Binary Sequences (APRBSs) using chaos system. The proposed algorithm scrambles information sequence by APRBSs, and one sequence would be chosen for transmission which it has smallest PAPR value. To inform the receiver which sequence had been sent, a Side Information (SI) is enclosed with the transmitted sequence. Because SI is very important, convolutional code with Viterbi-Soft Decision Decoding (V-SDD) would be used in this paper to protect SI against channel distortion. Simulation results state that the proposed algorithm gives excellent PAPR reduction performance and approximately same Bit Error Rate (BER) performance over AWGN and flat fading channels comparing with the conventional OFDM system. This means that BER performance does not affected by SI. Finally, in addition to improving PAPR reduction performance, the proposed algorithm provides a good data security due to chaos system as well as reduces the hardware and computational complexities in the conventional PAPR reduction scrambling techniques.