Wireless Power Transfer Aided with Reconfigurable Intelligent Surfaces: Design, and Coverage Analysis

This paper investigates the wireless power coverage in a network where intelligent reconfigurable surfaces (RISs), distributed according to a homogeneous Poisson point process, cooperate in the energy transfer from the power beacon to the harvesting devices. First, using energy beamforming and maximum ratio transmission, the harvested energy at a typical device is obtained. Then, leveraging stochastic geometry tools, and adopting an approach based on the moment generating function, the power coverage probability is obtained. For such, we also characterize the distributions of the channel gains and the device distances. Novel closed-form expressions for the coverage probability are provided for the cases when the wireless power transfer is assisted by multiple RISs, deployed in cascaded or distributed configurations, as well as when the power beacon is aided by a single RIS. The impact of the main network parameters on performance is analyzed. In particular, comparative results show the significant gains that can be achieved in the network coverage when multiple RISs cooperate in the wireless power transfer, as compared to the non-cooperative scheme.