Spectrum-efficient Index Modulation with Improved constellation Mapping

Recently, a scheme called Orthogonal Frequency Division Multiplexing (OFDM) with Generalized Index Modulation (OFDM-GIM) is proposed, in which the number of active subcarriers in an OFDM sub-block is adjustable and a higher spectral efficiency is achieved compared with the conventional Orthogonal Frequency Division Multiplexing with Index Modulation(OFDM-IM) scheme. In this paper, based on the general index modulation structure, a spectrum-efficient Index Modulation with Improved Mapping is proposed. In this scheme, each sub-block can use different constellation mappings as well as different numbers of active subcarriers to transmit information. We further propose the corresponding transmitter and the receiver structures. The simulation results show that the proposed system achieves a higher spectrum efficiency and better BER performance compared with the existing OFDM-IM schemes.