Opportunistic Passive Beamforming for RIS-Assisted WiFi Network: System Design and Experimental Validation

Reflecting intelligent surface (RIS) has been widely used to enhance radio signals in wireless communications. However, RIS’s capabilities, other than signal enhancement, are rarely investigated, which restricts RIS’s role in assisting wireless communications. In this article, we propose to apply RIS for joint signal enhancement and collision alleviation to the contention-based wireless access standards, e.g., IEEE 802.11 wireless local area network (WLAN). Inspired by the capture effect’s capability in collision alleviation, we design an opportunistic passive beamforming (OPBF) scheme that artificially introduces channel fluctuations to manage the capture effect. We realize the OPBF scheme through three steps, i.e., reflection pattern design, random index generation, and index-guided pattern switching. In addition, we develop a hardware prototype for validations in WiFi networks. The experiment results show that our scheme can effectively reduce collision rate and improve the system throughput.