In case of wireless communication systems, it is possible to manipulate the channel matrix ( not each elements only the channel correlation) using reconfigurable antenna switching. In communication network we also have the notion of network coding which some how change the channel variables between links. any way sorry for such general answer but  your question is a bit ambiguous. 

Thanks for the answers and your advices, I will try to rewrite the question.

Thanks, I will try to explain with more detail my question.