Spectral Efficient Frequency Division Multiplexing Aided with Tri-Mode Index Modulation in Mutli-Input Multi-Output Channels

This work presents spectral efficient frequency division multiplexing with tri-mode index modulation (TM-SEFDM) for multi-input multi-output (MIMO) wireless networks. In TM-SEFDM, a fraction of subcarriers are utilized for modulation with two differentiable constellation sets, while the rest remains inactive. This strategy enables the transmission of extra bits through the subcarrier indices that correspond to the activation pattern of two constellation alphabets. Spectral efficiency (SE) and bit error rate (BER) are used to investigate the system’s performance. The proposed MIMO-TM-SEFDM performs comparatively better than the conventional MIMO-SEFDM and MIMO-SEFDM with index modulation in SE and can achieve similar SE as MIMO dual-mode SEFDM analytically while being more energy efficient than DM. Both theoretic and numerical results for the MIMO-TM-SEFDM show improved error performance compared to the MIMO-SEFDM-IM system.