Design and Analysis of Grouping Non-Active Frequency -Time Index Modulation for Differential Chaos Shift Keying Communication System.

This paper introduces a new index modulation method called Grouping Frequency-Time Index Modulation Non-Active for Differential Chaos Shift Keying (GFTIM-DCSK-II). The proposed system exploits the advantages of index modulation (IM) so that both the energy and spectrum efficiency of the system are enhanced. The suggested system effectively employs both frequency and time resources, allowing for efficient transmission at large data rates. For each symbol period, the new approach divides all data bits into equal G groups. For each group, the system includes frequency index bits, denoted as m₁, which are utilized to choose a non-active subcarrier from a total of 2^m₁ subcarriers. Additionally, time index bits, denoted as m₂, are employed to select a single time slot from 2^m₂ total time slots. After that, the modulated bits m₀ are subjected to DCSK modulation and thereafter sent over the active subcarriers. Therefore, G(m₀+m₁+m₂), where m₀ = (2^m₁ 2^m₂ - 1), is the total amount of bits transmitted with the GFTIM-DCSK-II system. To better demonstrate the distinctive characteristics of the proposed scheme the energy efficiency, complexity, and spectral efficiency of the GFTIM-DCSK-II system in comparison to the most advanced alternatives available are thoroughly analyzed. The system with q=8, m₁=1, and m₂=1 saves around 40% more energy than the CTIM-DCSK system also the proposed system enhanced the spectral efficiency around five times more than CTIM-DCSK and GSIMDCSK-II with q=8, m₁ =1, and m₂ =4. Bit error rate (BER) formulas across multipath Rayleigh fading channels and additive white Gaussian noise (AWGN) are calculated analytically. The proposed system showed an enhancement in BER performance around 5 dB than CI-DCSK2 and GSTIM-DCSKII across the AWGN channel at a BER of 10^-4 at the same data rate. [ABSTRACT FROM AUTHOR]