Performance analysis of repeated index modulation for OFDM with MRC and SC diversity under imperfect CSI

In this paper, we conduct the investigation into the performance of repeated index modulation-orthogonal frequency division multiplexing (RIM-OFDM) system with spatial diversity comprising the maximal ratio combining (MRC) and selection combining (SC). The considered systems, abbreviated as RIM-OFDM-MRC and RIM-OFDM-SC, are successful in exploiting both the frequency and spatial diversities to provide improvement in the error performance of the conventional IM-OFDM system with diversity reception. We find out the closed-form expressions for the index and symbol error probabilities of RIM-OFDM-MRC and RIM-OFDM-SC under a variety of different channel conditions. We also carry out asymptotic analysis in order to examine the system behavior under influences of system parameters and the imperfection in channel state information (CSI). Performance evaluation through both theoretical and simulation results demonstrates the significant performance improvement of our systems in comparison with the conventional IM-OFDM using MRC/SC even when channel estimation errors occur at the receiver. © 2019 Elsevier GmbH