Dual‐Phase Malicious User Detection Scheme for IM‐OFDMA Systems Using IQ Imbalance

ABSTRACT Physical‐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.