 In an open-loop MIMO system with formula_1 transmitter antennas and formula_2 receiver antennas, the input-output relationship can be described as
where formula_9 is the formula_10 vector of transmitted symbols, formula_11 are the formula_12 vectors of received symbols and noise respectively and formula_13 is the formula_14 matrix of channel coefficients.An often encountered problem in open loop spatial multiplexing is to guard against instance of high channel correlation and strong power imbalances between the multiple streams.One such extension which is being considered for DVB-NGH systems is the so-called "enhanced Spatial Multiplexing (eSM)" scheme.