Design and analysis of grouping subcarrier index modulation for differential chaos shift keying communication system

Abstract

To sufficiently use the subcarrier index modulation in differential chaos shift keying (DCSK) of the recently suggested carrier index differential chaos shift keying (CI-DCSK) and two-layer carrier index differential chaos shift keying (2CI-DCSK), new subcarrier index modulation based DCSK is proposed and named grouping subcarrier index modulation DCSK (GSIM-DCSK). Two grouping subcarrier index modulations based DCSK systems are proposed named GSIM-DCSK-I and GSIM-DCSK-II systems. The data bits are split into L parallel groups, each group has (p1+p2) bits, where p1 bits are used as indexed bits and p2 are used for a modulated bit. The indexed bits are used as an index selector to select one active subcarrier as in GSIM-DCSK-I or inactive subcarrier as in GSIM-DCSK-II out of 2p index subcarriers. While the modulated bits are modulated by DCSK modulation. The bit error rate (BER) of the proposed systems are derived under additive white Gaussian noise and multipath Rayleigh fading channels, respectively. The simulation results are compared with analytical BER and conventional DCSK modulations. Furthermore, the energy efficiency, spectral efficiency, and complexity analysis are derived and compared with the conventional DCSK modulations. The results show that the proposed systems elevate the performance of the conventional DCSK system.