Joint Design for NOMA-Based Cell-Free Networks with Dual-Sided Wireless-Powered RIS

In this paper, an innovative active dual-sided wireless-powered (DSWP) reconfigurable intelligent surface (RIS) architec-ture is proposed to address the coverage limitations and eliminate the dependence on additional power source encountered by tra-ditional active RIS. By harvesting and storing energy, the DSWP RIS is capable of supplying the energy to drive the amplifier and process the incident signal from both sides simultaneously. Furthermore, we deploy the active DSWP RIS in a non-orthogonal multiple access (NOMA)-based cell-free network to improve the rate performance. We formulate a sum rate maximization problem by jointly designing the beamforming vectors at access points (APs), mode selection indicator, transmission and reflection (T&R) matrices on both sides of the RIS. To solve the non-convex problem, we propose an alternating optimization (AO) based algorithm to obtain the suboptimal solution. Numerical results illustrate that the DSWP RIS outperforms other RIS architectures in boosting rate performance.