Linear Framework of RIS-Assisted Downlink Communication System

Reconfigurable intelligent surfaces (RIS) has emerged as a promising approach for efficiently enhancing communication performance via passive signal reflection. However, in high-mobility scenarios like vehicular communications, the rapidly changing channel presents challenges in acquiring instantaneous channel state information (CSI) for RIS systems with many reflectors, impacting transmission reliability. To overcome this issue, we present an innovative equivalent linear framework equipped with a low-complexity transmitter signal waveform design and receiver signal detection method for downlink communication systems, substantially enhancing stability in fast fading environments. Simulation results indicate that the proposed designs achieve higher communication reliability with low complexity, significantly improving performance in high-mobility scenarios.