A Hybrid DCSK Scheme Combining Cyclic Shift Keying and Code Index Modulation

In this letter, a hybrid differential chaos shift keying (DCSK) scheme combining cyclic shift keying and code index modulation (CSK-CIM-DCSK) is proposed to improve data rate and bit error rate (BER) performance. In the CSK-CIM-DCSK system, the bit stream is divided into blocks ofmc + mₛ + 1bits, where themcbits are used for code index modulation and themₛbits are used for cyclic shift keying modulation, and the last one bit is modulated by DCSK. The analytical BER expressions of the CSK-CIM-DCSK are derived over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels and validated via simulations. Simulation results indicate that the BER performance of the CSK-CIM-DCSK is significantly improved in contrast to DCSK with code index modulation (CIM-DCSK). Furthermore, the BER performance of the proposed system is compared with other non-coherent chaotic modulation systems, and the results show the superiority of the proposed system.