Design of dual-mode 3D OFDM index modulation scheme and low complexity detection

A dual-mode three dimensional orthogonal frequency division multiplexing-index modulation (DM-3D-OFDM-IM) system is proposed to address the challenges of OFDM-IM technology in balancing the spectral efficiency and reliability. This scheme designs a dual-mode 3D constellation modulation based on traditional OFDM-IM. By loading two types of 3D constellation symbols onto active subcarriers, it increases the minimum Euclidean distance between constellation points while introducing an additional subcarrier activation mode, thereby effectively improving system spectral efficiency and enhancing system reliability. Meanwhile, a greedy detection based log-likelihood ratio detection algorithm is proposed, and the average bit error probability (ABEP) of the system is derived using the joint boundary technique. Simulation results show that the proposed DM-3D-OFDM-IM scheme achieves much better ABEP performance compared with the traditional OFDM-IM schemes, and the proposed detection algorithm has the characteristics of high reliability and low complexity.