How does a MIMO system use the multipath effect constructively?

Multipath/scattering occurs when wireless signals bounce off objects such as buildings, trees, cars) – causing the signals to arrive at the receiver at different times.  In a conventional SISO system, when a direct signal and a reflected signal arrive at the receiver at different times, they become destructive as they destroy bits and pieces of each other – making it difficult for the receiver to decode.

However, in a MIMO system, these multiple signals are realigned with each other to enhance the desired components and reject the interfering components.

This is an area where MIMO based systems shine – in a MIMO system, this additional multipath energy is used constructively to enhance the signal rather than degrading it.