Alaca, OzgurAlthunibat, SaudRiza Ekti, AliYarkan, SerhanMiller, Scott L.Qaraqe, Khalid A.2025-10-102025-10-1020252161-391510.1002/ett.702572-s2.0-105016905033https://doi.org/10.1002/ett.70257https://hdl.handle.net/20.500.14627/1183Physical-layer security techniques have contributed to the achievement of various security objectives in an efficient and lightweight manner. Thus, these techniques have been widely considered for limited-resource networks such as Internet of Things networks. Among the different security objectives, malicious user detection by exploiting physical-layer parameters has demonstrated efficient performance. In this work, malicious user detection in the recently proposed index modulation-based orthogonal frequency division multiple access (IM-OFDMA) is addressed. The proposed malicious user detection scheme exploits the hardware impairments, especially the in-phase and quadrature imbalance parameters, for both legitimate and malicious users to design a dual-phase efficient detection scheme. The proposed scheme accounts for the special characteristics of IM-OFDMA transmission that are different from other multiple-access techniques. The performance of the proposed scheme was evaluated considering detection probability and false alarm probability performance metrics. Moreover, closed-form expressions of these metrics were derived for both phases and were validated by Monte Carlo simulation results under different configurations of IM-OFDMA systems.eninfo:eu-repo/semantics/closedAccessIM-OFDMAIndex ModulationIQ ImbalanceMalicious User DetectionPhysical Layer AuthenticationPhysical Layer SecurityArticle