Reconfigurable Intelligent Surface Assisted Internet-of-Things: MAC Design and Optimization

In this paper, we propose a reconfigurable intelligent surface (RIS) assisted medium access control (MAC) protocol, termed RIS-MAC, which is used for uplink traffics and low power communications of a large number of users in Internet-of-Things (IoT) networks. In the proposed RIS-MAC protocol, RIS configuration parameters can be reserved for each user by introducing the negotiation phase before the real data transmissions. As the real data transmissions commencing, the RIS can be controlled to focus on the transceiver according to the reserved results and assist its energy-efficient data transmissions. Based on the proposed RIS-MAC, the problem is formulated to maximize the overall capacity by optimizing the negotiated parameters of RIS-MAC. The performance evaluations demonstrate the feasibility and effectiveness of RIS-MAC.