An OFDM-based chaotic DSSS communication system with M-PSK modulation

This paper investigates a Chaotic Direct-Sequence Spread-Spectrum (CDSSS) communication system based on Orthogonal Frequency-Division Multiplexing (OFDM) technique in combination with M-ary Phase Shift Keying (M-PSK) modulation. In the combination system, depending on the quality of transmission channel, the data rate can be adjusted flexibly by using M-PSK. Error rate performances through noise- and fading-affected channels are improved by means of CDSSS and OFDM, respectively. By replacing the conventional Pseudo-random Noise (PN) sequence with a NRZ-chaos sequence in CDSSS, data security of the combination system is enhanced significantly. A detailed description of the proposed system is first given. Numerical simulation and results are then shown in order to verify operation of the system and characterize the dependence of Bit Error Rate (BER) performance on the number of symbols, spreading factor and different chaotic sequences in both Additive White Gaussian Noise (AWGN) and Rayleigh Fading channels. Notable features on security of the system are also presented.