Effectiveness of Reconfigurable Intelligent Surface in Multipath Fading Channel

A method of simulating a single-input single-output reconfigurable intelligent surface (RIS) assisted channel is presented using three channel black boxes to represent the direct signal path, the transmit path to the RIS and the reflected path from the RIS. The complex coefficients for each channel box is obtained by ray tracing in a scenario with geographic terrain information that also contains approximate building shapes. The electrical characteristics of the ground and building walls were also accounted for in the ray tracing function. Simulations were conducted with reflected rays only and reflected rays together with diffracted rays. The received power exhibits variations typical of multipath fading environments. In the best locations, the RIS-assisted channel simulation result agrees well with theoretical models, the performance increasing by the RIS size squared as the number of RIS elements is increased. In the simplified theoretical model where the transmitter and receiver are inline and the RIS orthogonal but much closer than the distance between the former elements, the simulation results also corroborate best deployment close the transmitter or the receiver with a U-shaped drop between them.