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A brand-new framework for cascaded-reconfigurable intelligent surface (RIS) empowered multi-antenna non-orthogonal multiple access (NOMA) system is conceived, wherein RISs are deployed to serve their associated users and assist data transmission for the farther RISs as well. A new concept of RIS-level successive interference cancellation (RSIC) is developed to eliminate the inter-RIS interference. With the devised framework, a transmit power minimization problem is formulated by collaboratively designing each user’s transmit power, the RISs’ phase shifts, and the BS’s equalizers. Specifically, a parallel iteration method is developed to solve the subproblem of jointly optimizing transmit power and equalizers, whereas a sequential phase-rotation algorithm is proposed to address the subproblem of phase shift optimization. It is showed by simulations that the proposed scheme outperforms the existing …