Low complexity K-best detectors for MIMO-OFDM-IM system

As an alternative to classical multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM), MIMO-OFDM with index modulation (MIMO-OFDM-IM), which provides a flexible trade-off between spectral efficiency and error performance, has attracted considerable interest recently. However, in order to detect the active subcarrier indices and modulated symbols precisely, the receiver suffers from high complexity. In this paper, we propose two low-complexity K-best detectors for MIMO-OFDM-IM system. The first detector regards each OFDM with index modulation (OFDM-IM) subblock as a super symbol and retains K best nodes at each layer of the search tree. The second detector searches the K best nodes at the subcarrier level by reducing the size of the subblock to further reduce the complexity. Simulation results show that the proposed detectors offer comparable performance to the optimal maximum likelihood (ML) detector but with significantly reduced complexity.