Secure chaotic communication with spectrum expansion/compression

A security-enhanced chaos communication scheme by expanding and compressing the spectrum of modulated chaotic carrier is proposed, in virtue of a spectrum expansion module composed of two phase modulators and two dispersion mediums. The numerical results demonstrate that the efficient bandwidth of modulated chaotic carrier can be expanded up to several tens of GHz and the RF spectrum is uniformly flat. Moreover, the security of the proposed system is discussed by comparing the bit error ratio (BER) of legitimate receiver and that of eavesdroppers who try to extract message from the public link by the ways of direct filtering and synchronization utilization. It is indicated that the BER of illegal interception message is much larger than the legal one. The security of the proposed scheme is much higher than the conventional scenario without spectrum expansion and compression.