Security-Spectral Efficiency Tradeoff in STAR-RIS RSMA: A Max-Min Fairness Framework

Fuente: arXiv
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Main Authors: Xia, Huiyun, Mao, Yijie, Xu, Sai, Han, Shuai, Zhu, Hongbo
Format: Preprint
Published: 2026
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author Xia, Huiyun
Mao, Yijie
Xu, Sai
Han, Shuai
Zhu, Hongbo
author_facet Xia, Huiyun
Mao, Yijie
Xu, Sai
Han, Shuai
Zhu, Hongbo
contents Simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) enable full-space coverage but also expose wireless transmissions to security from multiple spatial directions. This paper investigates a STAR-RIS-assisted secure RSMA system where both internal and external eavesdroppers may coexist in the transmission and reflection regions. In such a scenario, the RSMA common stream simultaneously serves legitimate users, impairs external eavesdroppers, and avoids assisting internal eavesdroppers, leading to a challenging trade-off between spectral efficiency and confidentiality. To address this issue, we formulate a max-min fairness problem under secrecy constraints and develop an iterative algorithm to jointly optimize transmit beamforming and STAR-RIS phase shifts. Simulation results demonstrate that the proposed scheme improves spectral efficiency while maintaining confidentiality.
format Preprint
id arxiv_https___arxiv_org_abs_2603_26532
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Security-Spectral Efficiency Tradeoff in STAR-RIS RSMA: A Max-Min Fairness Framework
Xia, Huiyun
Mao, Yijie
Xu, Sai
Han, Shuai
Zhu, Hongbo
Information Theory
Simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) enable full-space coverage but also expose wireless transmissions to security from multiple spatial directions. This paper investigates a STAR-RIS-assisted secure RSMA system where both internal and external eavesdroppers may coexist in the transmission and reflection regions. In such a scenario, the RSMA common stream simultaneously serves legitimate users, impairs external eavesdroppers, and avoids assisting internal eavesdroppers, leading to a challenging trade-off between spectral efficiency and confidentiality. To address this issue, we formulate a max-min fairness problem under secrecy constraints and develop an iterative algorithm to jointly optimize transmit beamforming and STAR-RIS phase shifts. Simulation results demonstrate that the proposed scheme improves spectral efficiency while maintaining confidentiality.
title Security-Spectral Efficiency Tradeoff in STAR-RIS RSMA: A Max-Min Fairness Framework
topic Information Theory
url https://arxiv.org/abs/2603.26532