Low-complexity subcarrier-wise hierarchical search based ML detector for MIMO-OFDM-IM

Abstract

Multiple-input multiple-output orthogonal frequency division multiplexing with index modulation (MIMO-OFDM-IM) is a recently proposed multicarrier transmission technique for the energy-efficient next generation wireless communications. Traditional detectors need to search all subcarriers in each MIMO-OFDM-IM subblock jointly to avoid illegal active indices of combinations (AICs) of OFDM-IM subblock at each transmit antenna level, which requires tremendous search at the receiver. In this paper, we propose a novel low-complexity subcarrierwise hierarchical search (HS) algorithm aided near maximum likelihood (HS-ML) detector for the MIMO-OFDM-IM system, which first estimates the subcarriers in the MIMO-OFDM-IM subblock independently and employs the HS algorithm to obtain the estimate of the MIMO-OFDM-IM subblock with legal AICs. Thanks to the effectiveness of the HS algorithm, the proposed HS-ML detector can find the estimate of the MIMO-OFDM-IM subblock with considerably low search complexity and achieves near-optimal BER performance.