Performance Analysis of RIS-Empowered OFDM-IM Communications under Weibull Fading and Joint Tx/Rx I/Q Imbalance

Abstract

A modernist technique, reconfigurable intelligent surface (RIS) provides outstanding signal reflection and amplification, making it highly valuable for upcoming communication systems. Besides, a major contributor is index modulation (IM), attaining superior spectral and energy efficiency, and achieving hardware sufficiency. The primary and novel contribution of this work is the derivation of a highly accurate, closed-form approximate expression for the average bit error rate (ABER) of an orthogonal frequency division multiplexing (OFDM)-IM system operating in the complex and challenging environment characterized by joint transmitter/receiver (Tx / Rx ) in-phase and quadraturephase imbalance (IQI) and Weibull fading. This essential analytical achievement is facilitated by the newly formulated, closed-form pairwise error probability (PEP) expression specifically tailored to the maximum likelihood (ML) detector used in this non-ideal, effect of IQI on OFDM-IM system over the fading channel. Furthermore, this analysis is uniquely applied to quantify the precise performance impact of various RIS configurations under these simultaneous impairments. In addition the RIS configuration is shown to significantly enhance the overall system performance. Our results reveal that integrating RIS with OFDM-IM systems is an effective strategy to alleviate the undesirable impact of joint Tx and Rx IQI. The final and conclusive step of the work solidifies the analytical novelty by demonstrating that the derived closed-form ABER expressions are robust and accurate, as evidenced by the perfect match between the theoretical (analytical) results and the detailed Monte Carlo simulation results.