Decoupling of Non-square Mimo Control System with Size of (3*7)

How decouple the Mimo system transfer function decoupling using decoupler matrix?

Here there is a Mimo transfer function with size of 3*7 (3 inputs and 7 outputs).<pre>
G = [G11 G12 G13 G14 G15 G16 G17;
G21 G22 G23 G24 G25 G26 G27;
G31 G32 G33 G34 G35 G36 G37]</pre>
Is it possible to decouple the interaction between the loops and how can we get multi Siso system from G using decoupler matrix? Can any body prove the problem mathematically?

Thanks