Multiple-Input Multiple-Output OFDM With Index Modulation: Low-Complexity Detector Design

Multiple-input multiple-output orthogonal frequency division multiplexing with index modulation (MIMO-OFDM-IM), which provides a flexible trade-off between spectral efficiency and error performance, is recently proposed as a promising transmission technique for energy-efficient 5G wireless communications systems. However, due to the dependence of subcarrier symbols within each subblock and the strong interchannel interference, it is challenging to detect the transmitted data effectively while imposing low computational burden to the receiver. In this paper, we propose two types of low-complexity detectors based on the sequential Monte Carlo (SMC) theory for the detection of MIMO-OFDM-IM signals. The first detector draws samples independently at the subblock level, while the second detector draws samples at the subcarrier level with further reduced complexity. To meet the constraint of the subcarrier combinations within each subblock, the second detector is further coupled with a carefully designed legality examination method. Attributed to the effectiveness of legality examination and deterministic SMC sampling, both proposed detectors achieve near-optimal error performance for the MIMO-OFDM-IM system.

I. Introduction

With the increasing demand for higher spectral efficiency and reliability in the next generation wireless communications, multiple-input multiple-output (MIMO) systems have been receiving great attention for their ability in improving the transmission rate and error performance [1]– [3]. Recently, a novel MIMO scheme called spatial modulation (SM) has emerged as an appealing candidate to fulfill the spectral and energy efficiency requirements of the next generation wireless communication systems [4]– [10]. In SM, information bits are conveyed by not only the modulated symbol but also the index of the active transmit antenna. Compared with classical MIMO, SM has a number of advantages, including reduced interchannel interference, relaxed inter-antenna synchronization requirements, and reduced receiver complexity [6], [7]. Owing to its various advantages, design and analysis of SM transmission in various scenarios, e.g., adaptive SM [11]–[13], generalized SM [14]–[16], and energy evaluation of SM [17]– [20], are extensively investigated. Specially, for practical multipath fading channels, single-carrier aided SM [21]–[23] is conceived as an appealing technique to eliminate inter-antenna interference and achieve high energy efficiency with only one active antenna at any time instant. Compared with single-carrier transmission, orthogonal frequency division multiplexing (OFDM) is usually more favored for multipath fading channels as it facilitates low-complexity receiver design by converting the multipath fading channel into several parallel flat fading channels in the expense of an increased peak-to-average-power ratio (PAPR) at the transmitter.