Sum rate maximization in active RIS-assisted ambient backscatter communication system

This paper focuses on an active reconfigurable intelligent surface (RIS)-assisted ambient backscatter communication (AmBC) system. The explosive growth of the Internet of Things (IoT) has led to increasing demands for efficient communication, yet traditional BackCom systems face issues like weak signals and interferences. This study aims to maximize the sum rate of AmBC IoT devices (IoTDs) by jointly optimizing the beamforming vector at the BS, the power splitting coefficient at the IoTDs and the phase shifts of the active RIS. The constraints include the maximum transmit power of the BS, the power budget of the RIS, and the minimum energy harvesting requirements of each IoTD. The problem is decomposed into three subproblems for iterative solution. The simulation results demonstrate that active RIS can effectively improve the sum rate of AmBC IoTDs. Research has great potential to improve the communication capabilities of IoT devices, improve energy efficiency, and lay the foundation for the development of advanced wireless communication systems.