On the Impact of Transceiver Impairments and Reflecting Elements for RIS-Aided Communications

Reconfigurable intelligent surface (RIS) smartly reconfigures the radio-channel characteristics to assist the transmissions, thereby improving both the quality-of-service and radio connectivity. In this paper, RIS is adopted for downlink communication from a base station in a scenario where the direct link is severely blocked by obstacles. A more reasonable large-scale path loss model for RIS-aided communications is included by taking into account the physical characteristics of RIS. Furthermore, residual transceiver hardware impairment (RTHI) is considered to facilitate the practical nature of transceiver equipment. Based on the Rayleigh modeling for small-scale fading and the central limit theorem approximation for reflecting elements, we derive the signal-to-noise distribution and the tractable expression of ergodic achievable rate for the analysis. Finally, numerical results are presented to demonstrate the impact of RIS and transceiver design parameters, including number of reflecting elements, RTHI level, and placement and size of RIS.