A novel joint mapping scheme design with low PAPR aided differential chaos shift keying system

In order to further improve the transmission and spectral efficiency of the MC-DCSK system, a novel security system called Joint Mapping Multi-Carrier Differential Chaos Shift Keying (JM-MC-DCSK) is proposed in this paper. A novel joint mapping scheme is designed which consists of two parts: matrix reshaping mapping and combination mapping. Moreover, in order to correctly demodulate the information bits in the index obtained through Maximum Likelihood Estimation (MLE), we propose a new index mapping algorithm to match this joint mapping scheme. The information bits are first mapped into U mutually orthogonal matrices in the matrix reshaping mapping structure. In this structure, we employ segmental shifts of the orthogonal submatrices instead of cyclic shifts to eliminate intra-signal interference, which contributes to the reliability of the system. Then, in the combination mapping structure, the information bits are modulated by N orthogonal carriers after being replicated U times. In each carrier signal, we arbitrarily select two sequences from the U orthogonal chaotic sequences to be superimposed. This scheme can map more information symbols and the randomness of the combination selection provides more flexibility for the mapping algorithm. The Bit Error Rate is derived and analyzed under Additive White Gaussian Noise and Rayleigh Fading Channel by Gaussian approximation method and central limit theorem, and numerical simulations are conducted to verify the correctness of theory. Additionally, the simulation results demonstrate that the system also has lower BER and Peak-to-Average Power Ratio, reflecting its significant theoretical and practical engineering value.