Joint Grouping Subcarrier and Permutation Index Modulations Based Differential Chaos Shift Keying System

Abstract

A joint grouping subcarrier-permutation index modulation based differential chaos shift keying (GSPIM-DCSK) communication system is proposed in this paper in order to enhance the energy and spectral efficiency, and increase the data rate of grouping subcarrier index modulation in DCSK (GSIM-DCSK) system that was recently suggested. In this system, the reference chaotic sequence is loaded into a permutation generator block to construct different permuted replicas of the reference sequence, and the input data bits for each symbol duration are divided equally into G parallel groups, each group consisting of carrier index bits indicated by p1 used for selecting active or inactive subcarrier out of2p1 subcarriers for GSPIM-DCSKI and GSPIM-DCSKII systems respectively, and permutation index bits,p2, that are used to select one chaotic sequence out of 2p2 permuted replicas of the reference chaotic sequence and then used this sequence to spread the modulated bit,p3=1, to send it through active subcarriers so the total number of transmitted bits for GSPIM-DCSKI and GSPIM-DCSKII systems is G (p1+p2+ 1) and G (p1+(2p1-1)(p2 +1)) respectively. The expressions for energy and spectral efficiency, as well as the complexity of the suggested schemes, are determined and compared the outcomes with other traditional DCSK schemes. Under the influence of additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels, the analytical expressions for BER of the two proposed systems are derived. The simulated and analytical BER results are compared to confirm the precision of BER analysis. Additionally, a comparison is made between the findings of the proposed schemes and those of traditional DCSK schemes, indicating that the suggested methods boost the performance of traditional DCSK schemes.