Comparison of training, blind and semi blind equalizers in MIMO fading systems using capacity as measure

Semi blind/blind equalizers are believed to work unsatisfactorily in fading MIMO channels compared to training based methods, due to slow convergence or high computational complexity. We revisit this issue. Defining a ´composite´ channel for each equalizer, we compare the three algorithms based on the capacity of this channel. We show that, in a Rician (with line of sight, LOS) environment, semi blind/blind algorithms outperform training equalizers, but in Rayleigh channels, it is better to use training based methods. We also find the optimum training size in training and semi blind methods.