How to obtain a transfer function of an MPC controller?

I found that it is possible to obtain the transfer function of a MPC controller developed by using the MPC matlab toolbox (<http://cse.lab.imtlucca.it/~bemporad/teaching/mpc/stuttgart_2012/1-mpc.pdf> page 20, up-right slide). I would like to know if someone has some idea about the theory required to obtain the transfer function of the MPC controller: are there some resourcess, papers, etc. which describe the method? Thank you in advance!

Matteo