Cost-Efficient RIS-Assisted Transmitter Design With Discrete Phase Shifts for Wireless Communication

In this letter, in order to achieve higher spectral and energy efficiency, we propose a novel cost-efficient transmitter conceptual design based on reconfigurable intelligent surface (RIS) with discrete phase shifts. The key idea is to directly utilize the digital signal to adjust the discrete reflection coefficients of RIS, resulting that the phases of the reflected carrier signal being modulated without the need for complex digital signal processing (DSP) hardware and costly radio frequency (RF) chains. Furthermore, a joint digital modulation and beamforming method is developed to enable information transmission as well as enhance signal strength. Based on the proposed transmitter, we derive the closed-form expressions of the signal-to-noise ratio (SNR) and bit error rate (BER) of the received signal and analyze the impact of hardware constraints on communication performance. Extensive simulation results validate that the novel design of RIS-assisted transmitter provides a cost-effective and power-efficient solution for wireless communications.