Active Reconfigurable Intelligent Surfaces-Aided Wireless Communication System

In this letter, we investigate the use of active elements in reconfigurable intelligent surfaces (RIS) to overcome the double-fading problem introduced in the RIS-aided link in a wireless communications system. Towards this end, each active RIS element amplifies the reflected incident signal rather than only reflecting it has done in passive RIS modules. As revealed in our analysis and simulation, the use of active elements leads to a drastic reduction in the size of RIS to achieve a given performance level. Furthermore, a practical design for active RIS is proposed.