Weighted Sum Power Maximization for Self-Sustainable RIS-Assisted SWIPT

Self-sustainable RIS can harvest energy to maintain its operation by adaptively adjusting its reflection coefficient matrix, which brings convenience in deployment and maintenance. In this letter, we consider a self-sustainable RIS-assisted multi-input multi-output simultaneous wireless information and power transfer (SWIPT) system. Our aim is to maximize the weighted sum power received by energy users while considering the minimum data rate requirements of information users and the minimum energy demand of RIS. To tackle the non-convex and highly coupled sum power maximization problem, we first employ minimum-mean-square error (MMSE) method to reformulate the original problem. Subsequently, we propose a block coordinate descent-based framework that decouples the reformulated problem into two subproblems which can be solved iteratively. In addition, successive convex approximation (SCA) method is adopted to approximate the non-convex objective function and constraint. Finally, simulation results confirm that the self-sustainable RIS can significantly improve the energy transmission performance.