A High Data Rate Solution for Differential Chaos Shift Keying Based on Carrier Index Modulation

The carrier index differential chaos shift keying (CI-DCSK) modulation scheme transmits one reference and a single data-bearing wavelet over different subcarriers within one symbol duration, resulting in a limited bit rate and low spectral efficiency. In this brief, a novel CI-DCSK modulation scheme is proposed by transmitting multiple data-bearing wavelets together with one reference in a parallel way. Different Walsh codes are applied to separate these data-bearing wavelets so that they can share some subcarriers for index modulation and wavelet transmission. By removing or adding some data-bearing wavelets, the proposed scheme can achieve a high and adaptive data rate with better spectral and energy efficiencies. Furthermore, redundancies in the structure of transmitted signals can be exploited for noise reduction. Analytical bit error rate expressions of the proposed system are derived over the AWGN and the multipath Rayleigh fading channels, respectively. Finally, relevant simulations are performed for verification.