RIS-Based Wireless Sensor Networks: Passive Beamforming and Decision Gathering

By embedding each sensor into a reconfigurable intelligent surface (RIS) controller, in this letter we propose an efficient RIS-based wireless sensor network (WSN) for simultaneous passive beamforming and decision gathering. In RIS-WSN, the reflection amplitudes and phase shifts of RISs are designed to convey the local decisions made by sensors and boost the data transmission from a radio frequency source. We analyze the bit error rate (BER), decision error rate (DER), and sum rate performance of RIS-WSN over Rician fading channels by considering the presence of both direct and reflecting links. An upper bound on BER and an approximate expression for DER are derived in terms of data transmission and decision gathering, respectively. Computer simulations verify the analysis and show the superiority of RIS-WSN over the state-of-the-art method.