MIMO links mediated by Reconfigurable Intelligent Surfaces

In this work we investigate the possibility to realize a true MIMO communication scheme when the propagation between the transmitting and receiving arrays are mediated by a "Reconfigurable Intelligent Surfaces (RIS)", i.e. a surface containing many antenna-like devices, able to change the phase of the reflected wave. The analysis is based on a simple model already employed in a previous work highlighting the mirror vs. scatterer action of a RIS, depending on its size and on the distance to the transmitter and the receiver.