Secure and low papr ofdm system using chaotic map

Abstract

newline The new age communication systems require an increased data rate and spectrally efficient technologies. Orthogonal Frequency Division Multiplexing (OFDM) is a novel multicarrier modulation technique that finds its applications both in Radio Frequency (RF) networks and optical communication networks. It also meets the demands of high data rates, achieves high spectral efficiency and fights multipath fading through its orthogonality properties. Apart from its inherent benefits, the OFDM eliminates Inter Symbol Interference (ISI), lowers distortion and is simpler to implement. But with several separately modulated subcarriers, the OFDM encounters an elevated Peak-to Average Power Ratio (PAPR), which requires the output amplifier of the OFDM transmitter to be linear. Also, OFDM is reactive to Carrier Frequency Offset (CFO) and Doppler shift, which results in Inter-Carrier Interference (ICI). The OFDM signal generation maps an input digital data stream into subcarriers by Quadrature Amplitude Modulation (QAM) to form independent QAM symbols. These symbols are transformed into frequency domain data with a N-point Inverse Fast Fourier Transform (IFFT) and are equated to a Gaussian-distributed waveform. This causes high amplitude peaks in the signal and results in high PAPR of the OFDM signal. The evaluating parameter of the PAPR is Complementary Cumulative Distribution Function (CCDF). The CCDF denotes the probability at which maximum absolute value of the complex OFDM signal exceeds the fixed threshold.