Dual-Mode Time-Domain Index Modulation for Nyquist-Criterion and Faster-Than-Nyquist Single-Carrier Transmissions

In this paper, we propose a novel dual-mode time-domain single-carrier (SC) index modulation (DM-SCIM) scheme, where the combination of two constellation modes carries information bits further to modulated symbols, hence increasing the transmission rate. Accordingly, the proposed DM-SCIM scheme is capable of attaining a higher transmission rate than the conventional SC and SCIM schemes, without imposing any additional performance penalty. Furthermore, in order to maintain the detection complexity low enough to be tractable at the handset receiver, a successive detection algorithm, comprising minimum mean-square error (MMSE)-based frequency-domain equalization and log-likelihood ratio detection, is developed for both the conventional SCIM and the proposed DM-SCIM schemes. We also derive the error-rate bound of the proposed DM-SCIM scheme under the assumption of a channel-uncoded scenario. Moreover, in order to further increase bandwidth efficiency, the proposed DM-SCIM scheme is extended to the scenario supporting faster-than-Nyquist signaling, where the symbol interval in the time domain is set to be smaller than that defined by the Nyquist criterion. Our simulation results demonstrate the explicit performance advantage of the proposed schemes over the existing SC schemes. It is also revealed that our DM-SCIM scheme is capable of achieving a significantly lower peak-to-average power ratio than orthogonal frequency division multiplexing (OFDM) and OFDM with index modulation, while benefiting from a high reliability, which is achievable by multipath diversity.