Abstract

Configuration of a reconfigurable intelligent surface (RIS) as a solution to an optimization problem for spectral or energy efficiency requires the estimation of the channels between the transmitter and the RIS and between the RIS and the receiver. The channel estimation and the RIS configuration by optimization are computationally intensive processes in RIS assisted wireless links. The approach proposed in this paper simplifies and speeds up the RIS configuration process by relaxing the demand to find the optimal solution but instead aims to reach a predetermined channel quality measured with the signal-to-noise ratio. It is also shown that when a single dominant path exists between a mobile user and the RIS and also between the RIS and a base station, the RIS configuration calculated as a solution to a spectral efficiency maximization problem and configuration based on conventional antenna array beam steering give the same result.