| In today’s era of rapid development of the information industry, the amount of data needed to communicate is growing and people need a communication with faster speed and much more quality guaranteed. Thus, in the case of resource scarcity, the communication technology with high spectral efficiency, high energy efficiency, high performance is a research focus of wireless communications. Orthogonal frequency division multiplexing with index modulation(OFDMIM) is a recently developed transmission technique that extends the principle of spatial modulation to OFDM subcarriers. Several experimental studies have substantiated the potential benefits of OFDM-IM. In this paper, the performance of OFDM-IM in the presence of carrier frequency offset is studied in terms of bit error rate. It is shown via computer simulations that OFDM-IM has better robustness than classical OFDM in a certain carrier frequency offset range.A novel variant of OFDM-IM techniques called OFDM with in-phase/quadrature index modulation(OFDM-I/Q-IM), which carries additional information bits through the index domain including in-phase and quadrature dimensions, is recently proposed. In this paper, we propose a linear precoding OFDM-I/Q-IM scheme and give the optimal precoding matrix and the low-complexity maximum likelihood detector for the new scheme. We show with simulation results that the proposed scheme offers transmit diversity order of two and gives a significantly better error performance than OFDM-I/Q-IM. In addition, we propose OFDM with hybrid in-phase and quadrature index modulation(OFDM-HIQ-IM) by performing index modulation on the component in-phase and quadrature component per subcarrier. Different low complexity transceiver structures based on maximum likelihood detection or log-likelihood ratio calculation are proposed for OFDM-HIQ-IM. We show with simulation results that the proposed scheme achieves significantly better error performance than OFDM-I/Q-IM due to the additional coding gain. |
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