A reconfigurable intelligent surface (RIS) can shape the radio propagation by passively
changing the directions of impinging electromagnetic waves. The optimal control of the RIS
requires perfect channel state information (CSI) of all the links connecting the base station
(BS) and the mobile station (MS) via the RIS. Thereby the channel (parameter) estimation at
the BS/MS and the related message feedback mechanism are needed. In this paper, we
adopt a two-stage channel estimation scheme for the RIS-aided millimeter wave (mmWave) …

A reconfigurable intelligent surface (RIS) can shape the radio propagation environment by
virtue of changing the impinging electromagnetic waves towards any desired directions,
thus, breaking the general Snell's reflection law. However, the optimal control of the RIS
requires perfect channel state information (CSI) of the individual channels that link the base
station (BS) and the mobile station (MS) to each other via the RIS. Thereby super-resolution
channel (parameter) estimation needs to be efficiently conducted at the BS or MS with CSI …