Design and Analysis of a New Index-Modulation-Aided DCSK System With Frequency-and-Time Resources

We propose a new index-modulation-aided differential chaos shift keying (DCSK) system using frequency-and-time resources, referred to as CTIM-DCSK system, to achieve high-data-rate transmissions. In the proposed system, the orthogonal sinusoidal carriers are used to transmit both the reference-chaotic and the information-bearing signals. Moreover, the frequency-and-time resources are considered as indices to carry additional information bits. To simultaneously boost the bit error rate (BER) performance and reduce the system complexity, this paper proposes a new CTIM-DCSK signal based on the frequency-and-time resources, in which the time slots used by the selected subcarriers convey the same index bits. We employ a noise-reduction method at the receiver to further improve the BER performance of the proposed CTIM-DCSK system. We also derive the theoretical BER expressions of the CTIM-DCSK system over two different channels, i.e., additive white Gaussian noise (AWGN) channel and multipath Rayleigh fading channel. We analyze the data rate, complexity and spectral efficiency of the CTIM-DCSK system in comparison with the state-of-the-art counterparts. Analytical and simulation results verify the accuracy of the theoretical analysis and the advantage of the proposed CTIM-DCSK system. Consequently, the proposed CTIM-DCSK system appears to be a competitive candidate for low-complexity Internet-of-Things applications.