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.