Reed-Muller Code-Based Index Codebook Design for Dual-Mode OFDM-IM

The orthogonal frequency division multiplexing with index modulation (OFDM-IM) is a research topic attracting attention due to its ability to enhance efficiency by carrying additional bits. Recently, dual mode OFDM-IM (DM-OFDM-IM), which leverages inactive subcarriers to enhance spectral efficiency beyond OFDM-IM, has been extensively studied. Research efforts have focused on various aspects of DM-OFDM-IM, such as design of index codebooks, constellation design, symbol detection, and channel coding. However, the effect of index codebook design has not been widely considered in existing research. In this paper, we propose a construction method of index codebooks for DM-OFDM-IM based on the Reed-Muller codes. This approach aims to maximize the distances between index codewords so the index bit error rates are lowered and this also influences the demodulation of the symbol bits. It is shown via simulations that the proposed index codebook achieves lower overall bit error rates than conventional ones as well as index bit error rates for various modulation parameters.