Precoded Filterbank Multicarrier Index Modulation With Non-Orthogonal Subcarrier Spacing

In this paper, we propose a novel precoded non-orthogonal frequency division multiplexing (NOFDM) with subcarrier index modulation (SIM) to increase spectral efficiency for multicarrier systems. The proposed NOFDM-SIM scheme is constituted by a filterbank multicarrier system under reduced subcarrier spacing, where precoded index modulated symbols are mapped onto the subcarriers. The detrimental effects of inter-carrier interference (ICI) resulting from the non-orthogonality between subcarriers are efficiently mitigated with the aid of eigenvalue-decomposition-based precoding. Our simulation results demonstrate that the proposed precoded NOFDM-SIM system exhibits a similar peak-to-average power ratio to OFDM and OFDM-SIM counterparts while achieving the bit error rate limit of zero-ICI OFDM in a channel-uncoded setting. We analyze the power spectral density of the proposed scheme to demonstrate that the proposed scheme is strictly bandlimited, unlike its orthogonal counterpart. Furthermore, we present detailed investigations of the effects on ICI in the proposed scheme with and without precoding as well as power allocation. Finally, we introduce a three-stage iterative decoding architecture for our proposed scheme and show near-capacity error performance.