Index Modulation Based on Four-dimensional Spherical Code

In this paper, we propose an orthogonal frequency division multiplexing with index modulation (OFDM-IM) based on high-dimensional spherical codes. Unlike the traditional OFDM-IM system, which conveys the traditional M-ary constellation symbol on the active subcarriers, we use the adjacent subcarriers in the sub-block as a whole to be modulated based on high dimensional spherical code. Since the Euclidean distances between the constellation points increase by using high dimensional modulation, the performance of the OFDM-IM system is improved. We derive the general form of symbol error rate (SER) for the proposed OFDM-IM system with the maximum likelihood (ML) detection. The simulation results show that the bit error rate (BER) and SER of our proposed scheme is better than that of the traditional OFDMIM system. We also investigate the effect of channel estimation error on our proposed scheme.