I have read about MIMO (Multiple IN Multiple OUT) multiple antenna system help mitigate the multipath effects (like fading), otherwise occurring in a SISO i.e. single antenna system.
But I have been claims that MIMO antenna system is more productive if the multiple channels used by multiple antennas are highly uncorrelated with each other. If the channels are correlated then, the MIMO performance is as good as a SISO.
Any insights on why MIMO, to perform better, 'needs' to have an uncorrelated channel in a multipath environment.