High Data Rate Discrete-Cosine-Spreading Aided M-Ary Differential Chaos Shift Keying Scheme With Low PAPR

Traditional differential chaos shift keying (DCSK) systems have low spectrum efficiency since half of time slots are used to transmit the reference chaotic signals. Our objective is to utilize the orthogonality of chaotic vectors and orthogonal cosine functions to construct a high data rate M-ary modulation scheme while providing improved reliability over wireless channels. In this brief, we propose a discrete-cosine-spreading (DCS) aided M-ary DCSK scheme. In our design, we first utilize the Gram-Schmidt algorithm to generate orthogonal chaotic basis vectors, then the linear combination of these vectors is used for M-ary modulations to improve the data rate. In order to suppress the interferences between modulated signals and reduce the peak to average power ratio (PAPR) induced by the overlapping of linear combinations, subsequently we apply discrete cosine codes to spread the modulated symbols. The resultant symbols are respectively transmitted over the quadrature and inphase channels. Furthermore, we derive the theoretical bit error rate (BER) expression over additive white Gaussian noise (AWGN) channel and multipath Rayleigh channels, then we analyze the computational complexity. Simulation results validate the theoretical derivations, and demonstrate that compared with the benchmark schemes, the proposed scheme could achieve higher data rate with the improved bandwidth efficiency, better BER performances over multipath fading channels, and lower PAPR.