The effect of Spatial Multiplexing -Multiple Input Multiple Output (SM-MIMO) transmission technique on the performance of commonly used 4G-LTE detection techniques, was investigated. The channel environments used are Additive White Gaussian (AWGN), noise and heavy-tailed noise distributions as an actual noise distribution. The detectors characteristics were obtained by computer simulation for the case of un coded QPSK modulation, and open loop spatial multiplexing.Index Terms -Spatial multiplexing, MIMO, sub-optimal & optimal detectors, uncertain channel noise model.