A Spectrum-Efficient M-ary Correlation Delay Shift Keying Scheme for Non-coherent Chaotic Communications

Considering the signal structure of a differential chaos shift keying (DCSK) scheme, the reference and information-bearing signals are transmitted sequentially, thereby increasing the probability of being detected by a malicious eavesdropper and degrading the system security. Against this background, a spectrum-efficient M-ary correlation delay shift keying (M-ary CDSK) scheme is proposed in this paper, where a digital signal processing technique, namely QR decomposition, is applied to different chaotic signals to cancel the intrasignal interference completely. The M-ary CDSK scheme can not only improve the system security by embedding the reference signal into the M-ary information-bearing signal, but also achieve better spectral efficiency by M-ary modulation. The analytical bit error rate (BER) expressions are derived to verify the validness of the proposed scheme. Simulation results indicate that the M-ary CDSK scheme is capable of obtaining 1 to 4dB performance gain better than other schemes and providing a reliable solution for non-coherent chaotic communications.