Detection schemes that can outperform the conventional Orthogonal Space-Time Block Code (STBC) in real practical situations (imperfect CSI, time-varying fast fading channels, spatially correlated channels, ...) are investigated. This article focuses on the case of 2×1 and 2×2 MIMO systems, which are attractive in IoT and industrial communications due to multiple antennas design cost and need of fast prototyping. Indeed, large MIMO arrays are not suitable for reconfigurable intelligent surface (RIS) and 5G Reduced Capability (RedCap) devices where coding/decoding complexity has to be low. The optimization of 2×2 MIMO systems is therefore receiving renewed interest.