ABSTRACT
This chapter addresses the use of the RIS to aid wireless communications from a system perspective. The first section provides some system models that can be used to analyze the theoretical performance of a metasurface-based relay. The importance of joint optimization of precoding between the base station and the RIS is evident during the performance optimization of the above system model. Then, several beamforming techniques for the RIS are discussed, including based on a geometric relationship of the base station, RIS, and mobiles, or based on certain statistics of the measurement. Then, the channel estimation and feedback are described in certain level details. A direction-finding technique is also discussed, which is unique to RIS systems. Simulation methodologies and extensive simulation results, both of link level and system level of RIS, are presented with a different RIS layout, sizes, etc., where significant gains are observed by deploying the RIS to mobile networks.
