Hi mhammouda,
In NI jargon, we typically refer to this as "channel emulation" instead of "modeling", so I think searching with those terms will improve your search results.
I've found the following NI community post and example program that will hopefully be useful!
Channel Emulation Example for the NI PXIe-5644R
Real-Time MIMO Channel Emulation on the NI PXIe-5644R
Ashley G.
Senior Applications Engineer | RF & Wireless Communications