OFDM with Enhanced Layered Index Modulation

In this paper, a novel modulation scheme called Orthogonal Frequency Division Multiplexing with Enhanced Layered Index Modulation (OFDM-ELIM) is proposed to improve spectral efficiency (SE). Specifically, all subcarriers are divided into ${L}$ layers, which needs to be mapped by order and the number of active subcarriers in particular layer is alterable. The candidate subcarriers to be activated would decrease with layers increasing and constellations between different layers must be distinguishable for detection. It is proved that OFDM-ELIM can improve the SE and BER performance. We also design a universal low complexity detector for IM-based multicarrier systems with slight BER loss. Simulation results show that the BER performance of OFDM-ELIM is better than conventional OFDM-IM, especially in low SNR region.