Dual-Mode Differential Chaos Shift Keying With Index Modulation

In this paper, a dual-mode differential chaos shift keying with index modulation (DM-DCSK-IM) is proposed. In the proposed system, the bit stream is partitioned into two subblocks, where the first subblock is the mapped bits used to select the active time slot, which presents the time slot's constellation mode, and the second subblock is the modulated bits, which are further divided into two groups and modulated by a pair of distinguishable modem-mode constellations, respectively. Unlike the recently proposed pulse-position-modulation differential chaos shift keying (PPM-DCSK), since both the active and inactive time slots are applied to convey the information bits, the data rate of the proposed system can be promoted significantly. In order to detect the active time slots and recover the mapped bits as well as modulated bits correctly, we propose an effective detection algorithm for the proposed system. Furthermore, the theoretical bit error rate (BER) expressions are derived over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels, and the simulation results validate the accuracy of our derivations. Finally, the BER performance of the proposed system is compared with the other non-coherent chaotic communication systems, and the results indicate that the proposed system can offer competitive and satisfactory BER performance.