Impact of Constellation and Index Mapper Selection in OFDM-IM Systems

Orthogonal frequency division multiplexing with index modulation (OFDM-IM) offers significant flexibility to address the diverse communication scenarios of 5G and beyond. However, the selection of an appropriate index mapper remains an unresolved issue that could pose challenges to the standardization of OFDM-IM. Through the evaluation of a specific example in this paper, it is observed that without optimizing the index mapper, a performance loss of approximately 0.7 dB (SNR gain) may occur. Additionally, we discovered that the optimized index mapper can be universally applied to various constellations, despite OFDM-IM exhibiting sensitivity to subcarrier power variations.