An improved repeated correlation delay shift keying modulation scheme for chaotic communication system

The correlation delay shift keying (CDSK) and differential correlation shift keying (DCSK) technology are non-coherent modulation schemes to avoid the complex synchronous design for chaotic communication system. However, these two schemes degrades the bit error rate (BER) performance and security respectively. In this paper, we present a novel repeated CDSK (R-CDSK)modulation scheme to improve the BER performance. In our design, we transmit both the chaotic modulated symbol and the differential version to enhance the BER performance and system security. Namely, we firstly transmit the modulated symbol, which is the summation of chaotic signal and information modulated by delayed chaotic sequence, then the differential version of this modulated symbol is transmitted over the channels. Furthermore, we set up the mathematical model for the presented scheme and derive the BER expressions for the proposed R-CDSK modulated chaotic system. Simulations over additive white Gaussian noise (AWGN) channel show that the BER performance of the proposed R-CDSK system is much better than that of CDSK and comes close to DCSK. In addition, the security performance of proposed system is similar to that of CDSK system, which is superior to DCSK system. It is demonstrated that the presented R-CDSK scheme improves the BER performance and offers high security for the users.