STAR-RIS Assisted MISO-NOMA Networks : A Simultaneous Signal Enhancement and Interference Mitigation Design

Li, Jie and Song, Zhengyu and Hou, Tianwei and Huang, Chongwen and Li, Anna and Zhou, Gui and Liu, Yuanwei (2024) STAR-RIS Assisted MISO-NOMA Networks : A Simultaneous Signal Enhancement and Interference Mitigation Design. IEEE Transactions on Communications. ISSN 0090-6778

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Abstract

Simultaneous transmitting and reflecting (STAR) reconfigurable intelligent surface (RIS) technique has recently received considerable attention due to its omni-directional radiation capability. In this paper, motivated by the interference-mitigation-based (IMB) and signal-enhancement-based (SEB) designs, we introduce an innovative STAR-RIS assisted simultaneous-signal-enhancement-and-interference-mitigation (SSEIM) design in non-orthogonal multiple access (NOMA) multiple-input single-output cellular communication networks. Our objective is to maximize the system spectral efficiency (SE) by jointly optimizing the reflection and transmission phase shifts at the STAR-RIS, the precoding matrix of BSs, and the power allocation factors of NOMA users. We propose a low-complexity simultaneous enhancement and mitigation algorithm. Furthermore, by exploiting the manifold optimization technique, we introduce the Riemannian conjugate gradient algorithm to solve the non-convex subproblems with unit modulus constraint. Our analysis reveals that the proposed SSEIM design exceeds the traditional RIS-aided SEB and IMB designs.