Reconfigurable Intelligent Surface: MIMO or radiating sheet?

  title={Reconfigurable Intelligent Surface: MIMO or radiating sheet?},
  author={Sotiris Droulias and Angeliki Alexiou},
A Reconfigurable Intelligent Surface (RIS) redirects and possibly modifies the properties of incident waves, with the aim to restore non-line-of-sight communication links. Composed of elementary scatterers, the RIS has been so far treated as a collection of point scatterers with properties similar to antennas in an equivalent massive MIMO communication link. Despite the discrete nature of the RIS, current design approaches often treat the RIS as a continuous radiating surface, which is… 

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