Subcarrier Index Modulation Aided Non-Coherent Chaotic Communication System for Underwater Acoustic Communications.

In this paper, a subcarrier index modulation aided code-shifted differential chaos shift keying (SIM-CS-DCSK) system based on orthogonal frequency division multiplexing (OFDM) is proposed. In the proposed system, the transmitted bits are divided into two parts, where one part is used for conventional CS-DCSK modulation and the other part, served as subcarrier mapping bits, is used for the subcarrier index modulation. Benefiting from index modulation, SIM-CS-DCSK can achieve higher data rate compared to conventional multicarrier CS-DCSK system. Numerical simulations indicate that SIM-CS-DCSK has good BER performance over the time and frequency selective fading channels. Specifically, the proposed system outperforms the multicarrier spread-spectrum system (MCSS) by 0.5 dB to 2 dB. Real-field experiments in water pool and lake also confirm the superiority of the proposed system.