Search

As a novel wireless transmission scheme, multi-mode orthogonal frequency division multiplexing with index modulation (MM-OFDM-IM) is proposed recently, where multiple distinguishable constellations (modes) and their full permutation are employed for data transmission. However, the minimum intra-mode distance (MIAD) and inter-mode distance (MIRD) of the two dimensional (2D) multi-mode constellation decrease significantly as the constellation size becomes larger, degrading the error performance of the system. To meet this challenge, we propose a new modulation technique called high-dimensional MM-OFDM-IM (HM-OFDM-IM), where the high dimensional (HD) multi-mode constellations with considerably larger MIAD and MIRD are utilized. Besides, since index bits which consumes no energy accounts for larger proportion, the proposed scheme achieves higher energy efficiency (EE). However, HM-OFDM-IM can not provide any diversity gain, which is critical for the ultra-reliable communication in the fading channel. Therefore, the fading-resistant HM-OFDM-IM (RF-HM-OFDM-IM) is also proposed by introducing the rotated signal constellation, where the diversity order of symbol bits is identical with the dimension of the constellation. By minimizing the maximum pairwise error probability (PEP), the optimal rotation angles are obtained. Finally, the proposed schemes, as revealed by the theoretical analyses and simulation results, provide the better error performance compared with state-of-the-art IM-based schemes in the Rayleigh fading channel.