M-ary code-shifted differential chaos shift keying with in-phase and quadrature code index modulation

Abstract

In this study, an M-ary code-shifted differential chaos shift keying system with in-phase and quadrature code index modulation (I/Q-CIM-CS-MDCSK) is presented. In the proposed system, the information bits are conveyed not only by the M-ary constellation symbols, but also by the specific Walsh codes indices corresponding to the in-phase and quadrature branches of M-ary information bearing signals. Since the reference signal and the multiple M-ary information bearing signals are overlapped and transmitted within the identical time slot in a parallel manner, the spectral efficiency of the I/Q-CIM-CS-MDCSK system is enhanced significantly. In addition, the analytical bit error rate (BER) expressions for the presented system are derived under the additive white Gaussian noise and multipath Rayleigh fading channels. Finally, the BER performance of the proposed system is compared to other chaotic communication systems. The results manifest that the I/Q-CIM-CS-MDCSK system is a promising and competitive chaotic communication scheme.