Low-Complexity Suboptimal ML Detection for OFDM-IM Systems

frequency division multiplexing with index modulation (OFDM-IM) is a novel multicarrier scheme, which uses k out of n subcarriers as active subcarriers to trans-mit data. For detecting the subcarrier activation pattern (SAP) at the receiver, maximum likelihood (ML) detection cannot be used because of its high computational complexity. Instead, the detec-tor selecting the most likely active k subcarriers is used, which is called a k largest values (klv) detector. However, this method degrades the detection performance especially if the ratio of ille-gal SAPs to SAPs is high. In this letter, the suboptimal ML detector is proposed, which is a simple modification of the klv detector, but very efficient. The proposed detector has a similar detection performance compared to the ML detection, which is suitable for flexible implementation of OFDM-IM systems.