Chaos communication system based on time index chaotic shape-forming filter

In order to improve the energy efficiency of chaotic signals generated by chaotic shape-forming filters, a chaotic communication system was proposed based on time indexed chaotic shape-forming filters. In this system, time index modulation was applied in the process of generating chaotic signals, and additional information bits were transmitted by the vacancy of the basis function pulses. This improved the energy efficiency of chaotic signals generated by traditional chaotic shape-forming filters, while the transmission of chaotic reference signals was avoided. At the receiver, a chaotic matched filter was used to demodulate the information bits based on the minimum absolute value detection and polarity decision. Theoretical bit error rate formulas were derived for both the additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels. The simulation results show that the proposed system can improve not only the energy efficiency but also the bit error rate performance.