Repeated in-phase and quadrature index modulation for OFDM

Abstract

In this paper, we proposed the application of the repetition code to improve the performance of the index modulation for orthogonal frequency division multiplexing (IM-OFDM) system termed as repeated in-phase and quadrature index modulation for OFDM (RIQ-IMOFDM). The proposed scheme can provide a superior performance over the benchmark systems at the same spectral efficiency. Unlike the classical IM-OFDM, RIQ-IM-OFDM activates only a subset of sub-carriers and uses the indices of active sub-carriers to carry additional data symbols in the index domain of both in-phase and quadrature dimensions. Then, active sub-carriers in each in-phase/quadrature component transmits the same Mary symbol. Exploiting the in-phase/quadrature index modulation allows the system to attain improved spectral efficiency while using the repeated transmission provides the diversity gain in the frequency domain and thus improving the reliability of the conventional IM-OFDM as well as in-phase and quadrature index modulation for OFDM (IQ-IM-OFDM) systems.