On the Performance of RIS-Assisted OFDM-IM: Impact of Hardware Impairments

Orthogonal frequency division multiplexing (OFDM) is frequently utilized as a modernist technique, while constructing new wireless applications. It has been adopted in many wireless communications standards. Moreover, index modulation (IM) techniques brought a new breath to OFDM thanks to their advantages of providing spectral/energy efficiency and hardware convenience. However, high carrier frequencies are used for the fifth generation and beyond (5GB) wireless systems, and thus, it can be difficult to completely suppress the unfavorable interference effects stemming from the hardware impairments (HWIs). Since the HWIs can significantly reduce the performance of the wireless systems, mitigating their destructive impacts should be one of the important issues to consider, while designing wireless communication systems. At this point, reconfigurable intelligent surfaces (RISs), which control the propagation environment by modifying radio waves, can be exploited to improve the signal quality. Considering that, this paper investigates the performance of an RIS-assisted OFDM-IM system under the effect of the HWIs by using a maximum likelihood (ML) detector as well as a log-likelihood ratio (LLR) detector. Computer simulation results are provided to illustrate the adverse effects of the HWIs on RIS-Assisted OFDM-IM system. It is observed that including an RIS into OFDM-IM systems provides considerable performance improvement.