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arXiv · 2508.09020

Improved SINR Approximation for Downlink RSMA-based Networks with Outdated Channel State Information

Maria Cecilia Fernández Montefiore·Gustavo González·F. Javier López-Martínez·Fernando Gregorio
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Abstract

Understanding the performance of multi-user multiple-input multiple-output (MU-MIMO) systems under imperfect channel state information at the transmitter (CSIT) remains a critical challenge in next-generation wireless networks. In this context, accurate statistical modeling of the signal-to-interference-plus-noise ratio (SINR) is essential for enabling tractable performance analysis of multi-user systems. This paper presents an improved statistical approximation of the SINR for downlink (DL) MU-MIMO systems with imperfect CSIT. The proposed model retains the analytical simplicity of existing approaches (e.g., Gamma-based approximations) while overcoming their limitations, particularly the underestimation of SINR variance. We evaluate the proposed approximation in the context of Rate-Splitting Multiple Access (RSMA)-enabled MIMO DL systems with outdated CSIT. The results demonstrate excellent accuracy across a wide range of system configurations, including varying numbers of users, antennas, and degrees of CSIT staleness.

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Maria Cecilia Fernández Montefiore, Gustavo González, F. Javier López-Martínez, Fernando Gregorio. 2026-07-14. Improved SINR Approximation for Downlink RSMA-based Networks with Outdated Channel State Information. https://arxiv.org/abs/2508.09020

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