Resource Allocation for a Secure SWIPT Network Aided by a RIS Relying on S-Parameter Communication Model

In the Internet of Things (IoT) based scenarios, the network may encounter significant issues related to energy and communication as a result of a progressively growing number of terminals. We introduce simultaneous wireless power transfer (SWIPT) technology assisted by a reconfigurable intelligent surface (RIS) to counteract this challenge. Thus, the network's flexibility and reliability will be further enhanced. According to this system architecture, the scattering-parameter-based communication model is introduced to disclose hardware features for an energy efficiency (EE) maximization problem. Specifically, the potential unauthorized demodulation is also considered in the problem formulation. To resolve the issue, an alternative strategy is utilized to optimize iteratively the coupled variables. In particular, the block coordinate descent (BCD) approach based on the Sherman-Morrison formulais proposed to solve the RIS subproblem. The numerical results prove the hardware effects cannot be dismissed lightly. Besides, the configuration of the RIS may impact the network performance directly.