Efficient Index Modulation Techniques for 5G and Beyond

Index modulation (IM) techniques are emerging as promising approaches to improve spectral efficiency and reliability for 5G/future wireless networks. This paper provides an overview of key IM schemes including spatial modulation, orthogonal frequency division multiplexing with index modulation (OFDM-IM), and enhanced variants like SIM-OFDM. The spectral efficiency gains of these techniques are quantified mathematically. Spatial modulation uses antenna indices to convey additional information bits, while OFDM-IM utilizes subcarrier indices. SIM-OFDM further activates sub-carriers selectively based on incoming bits. Experiments demonstrate spectral efficiency improvements over classical OFDM.