Reference-Adaptive CDSK: An Enhanced Version of Correlation Delay Shift Keying

In this brief, a new chaotic communication scheme, named reference-adaptive correlation delay shift keying (RACDSK) is proposed as an enhanced version of CDSK. According to the relationship between adjacent information symbols, our scheme employs the information-bearing signal or the sequence generated by the discrete-time chaotic circuit as the reference signal for the next bit period. As a result, compared with CDSK and its improved schemes, the uncertainty caused by intrasignal interference and noise interference is made lower when the received signal correlates with its delayed version at the receiver. The bit-error-rate (BER) performance of our scheme is also studied analytically based on Gaussian approximation for discrete- time implementations. Simulations in additive white Gaussian noise channel are performed and compared with CDSK, generalized CDSK (GCDSK), and single-input-multiple-output CDSK (SIMO-CDSK). Results show that the BER performance of RACDSK is always much better than CDSK and GCDSK, and can even outperform SIMO-CDSK with a small spreading factor and at a high E_b/N₀ level. Moreover, for different E_b/N₀ levels, the best BER performance of RA-CDSK can be gained with a reasonable spreading factor.