Two decades of MIMO design tradeoffs and reduced-complexity MIMO detection in near-capacity systems

A pair of salient tradeoffs have driven the MIMO systems developments. More explicitly, the early era of MIMO developments was predominantly motivated by the multiplexingdiversity tradeoff between the Bell Laboratories Layered Space- Time (BLAST) and Space-Time Block Coding (STBC). Later, the Linear Dispersion Code (LDC) concept was introduced to strike a flexible tradeoff. The more recent MIMO system designs were motivated by the performance-complexity tradeoff, where the Spatial Modulation (SM) and Space-Time Shift Keying (STSK) concepts eliminate the problem of Inter-Antenna Interference (IAI) and perform well with the aid of low-complexity linear receivers without imposing a substantial performance loss on generic ML/MAP aided MIMO detection. Against the background of the MIMO design tradeoffs in both uncoded and coded MIMO systems, in this treatise, we offer a comprehensive survey of MIMO detectors ranging from hard-decision to softdecision. The soft-decision MIMO detectors play a pivotal role in approaching to the full performance potential promised by the MIMO capacity theorem. Having said that, in the near-capacity system design, the soft-decision MIMO detection dominates the total complexity, because all the MIMO signal combinations have to be examined, when both the channel’s output signal and the a priori LLRs gleaned from the channel decoder are taken into account. Against this background, we provide reducedcomplexity design guidelines, which are conceived for a widerange of soft-decision MIMO detectors