Reconfigurable intelligent surfaces (ris) assisted line-of-sight (los) multiple-input multiple-output (mimo) for range extension at terahertz (thz)

Abstract

A method, implemented by a processor connected to a reconfigurable intelligent surface (RIS) system that includes one or more RISs, includes detecting one or more wireless control signals from a transmitter. The method includes identifying a channel state and one or more phases based on the detected wireless control signals; improving a beam-steering reflection matrix (Φ) of the RIS system based on a singular value decomposition of channel matrices; and configuring the RIS system based on the Φ. Among the RISs, each RIS is configured to redirect an incident signal toward an antenna array of an intended receiver. The incident signal is received from the transmitter. Locations of the RIS and transmitter differ by a height placement value (h). In a horizontal plane, the location of the RIS is a first distance (D) from the transmitter and a second distance (D) from the receiver.