A New High-Efficiency Multilevel Frequency-Modulation Different Chaos Shift Keying Communication System

Considering the large number of delay lines and orthogonality Walsh code sequences in the traditional multilevel frequency-modulation different chaos shift keying (FM-DCSK), in this paper, we propose a new multilevel FM-DCSK, named multilevel M-ary FM-DCSK (MFM-DCSK). The MFM-DCSK transmits multilevel symbols directly in the communication channel without using orthogonality Walsh code sequence. Based on this, the MFM-DCSK can reduce computation complexity and time delay and improve transmission rate dramatically. In this paper, we also evaluate the bit error rate (BER) performance of the MFM-DCSK in an additive white Gaussian noise channel, a multi-path Rayleigh fading channel, and a multiuser channel. Compared with the conventional chaos communication algorithms, the MFM-DCSK can improve the integrated performance of the communication algorithm significantly. Moreover, we also define the utility of the chaos communication algorithm, which takes the transmission rate, the number of delay lines, and the BER into consideration. According to this definition, we deduce the optimal value of M for both MFM-DCSK and traditional M-ary FM-DCSK algorithms.