Power Minimization of Multiuser FAS–RIS Downlink System

Both fluid antenna system (FAS) and reconfigurable intelligent surface (RIS) are promising technologies that enhance the performance of wireless communications. This letter studies the power minimization problem under quality of service (QoS) constraints in a multiuser FAS-RIS-aided system, where each user is equipped with a planar FAS, and the base station (BS) has multiple fixed-position antennas (FPAs). The precoding vectors, the RIS elements, and the user antenna positions are iteratively optimized to minimize the transmit power. Our simulation results show that the proposed approaches require much less transmit power to achieve the QoS than the FPA counterpart.