STAR-RIS-Assisted Full-Duplex Symbiotic Radio

A novel simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-assisted full-duplex symbiotic radio (SR) communication paradigm is conceived in this letter. The transmission functionality of the STAR-RIS is used to enhance the downlink transmission, while the reflection functionality is adopted to transmit Internet-of-Things (IoT) data to the full-duplex base station (BS). Compared to the typical RIS-assisted SR, the proposed SR has lower receiver complexity and higher IoT transmission rate. The weighted sum-rate of the downlink users is maximized via jointly optimizing the beamforming coefficients at the BS and the STAR-RIS. Simulation results confirm the effectiveness of the proposed SR system and reveal the performance trade-off between the downlink and IoT transmissions.