Abstract: In the FM-QCSK(Frequency Modulated Quadrature Chaos Shift Keying) communication system, frequency modulation of the continuous-time chaotic signal makes it possible to generate an inherent wideband signal with constant energy per bit. For the chaotic sample function, a set of orthogonal bases can be used to produce the quadrature signal of the chaotic carrier in the frequency or time domain. In the receiver, the reference signal and its quadrature component are directly correlated with the information-bearing part without FM demodulation. In this way, a symbol can once represent 2-bit information to achieve the higher rate of transmission. Simulation results show that the BER performance of FM-QCSK is close to that of FM-DCSK in the AWGN channel, and that compared with traditional periodical carrier modulation, this scheme is robust to the frequency selective fading in the multipath channel.

Key words: FM-QCSK, noncoherent detection, chaotic carrier, performance analysis