Reconfigurable intelligent surfaces (RIS) assisted line-of-sight (LOS) multiple-input multiple-output (MIMO) for range extension at terahertz (THz)

An apparatus comprising:

• a reconfigurable intelligent surface (RIS) configured to:
• redirect an incident electromagnetic (EM) signal toward an antenna array of an intended receiver that is a receiver base station, the incident EM signal received from an antenna array of a transmitter at a wavelength (2);
• and
• extend a range between the transmitter and a receiver base station,
• wherein:
• the RIS includes a plurality of passive reflectors arranged such that an arrangement of the passive reflectors within the RIS includes a uniform linear array that includes a number (W) of reflector panels separated by a reflector panel separation distance (dRIS) that is equivalent to an antenna panel separation distance (dt) of the transmitter;
• in a vertical plane, a location of the RIS above ground differs from a vertical location (ht) of the transmitter by a height placement value (hRIS);
• and
• in a horizontal plane, the location of the RIS is a first distance (DTX-RIS) from the transmitter and a second distance (DRX-RIS) from the receiver base station;
• and
• an RIS controller operably connected to the RIS, the RIS controller configured to:
• detect one or more wireless control signals from the transmitter;
• identify a channel state and one or more phases based on the one or more detected wireless control signals;
• improve a beam-steering reflection matrix (Φ) of the RIS based on a singular value decomposition of channel matrices;
• and
• configure the RIS based on the beam-steering reflection matrix.

A non-transitory computer readable medium embodying a computer program, the computer program comprising computer readable program code that when executed causes at least one processor to:

• establish a connection to a reconfigurable intelligent surface (RIS) system that includes one or more RISs;
• detect one or more wireless control signals from a transmitter;
• identify a channel state and one or more phases based on the one or more detected wireless control signals;
• improve a beam-steering reflection matrix (@) of the RIS system based on a singular value decomposition of channel matrices;
• and
• configure the RIS system based on the beam-steering reflection matrix,
• wherein the one or more RISs extend a range between the transmitter and a receiver base station,
• wherein among the one or more RISs, each RIS is configured to redirect an incident electromagnetic (EM) signal toward an antenna array of an intended receiver, each RIS includes a plurality of passive reflectors arranged such that an arrangement of the passive reflectors within the RIS includes a uniform linear array that includes a number (W) of reflector panels separated by a reflector panel separation distance (dRIS) that is equivalent to an antenna panel separation distance (dt) of the transmitter, the incident EM signal received from an antenna array of a transmitter at a wavelength (λ), and
• wherein:
• in a vertical plane, a location of the RIS above ground differs from a vertical location (ht) of the transmitter by a height placement value (hRIS);
• and
• in a horizontal plane, the location of the RIS is a first distance (DTX-RIS) from the transmitter and a second distance (DRX-RIS) from the receiver base station.