Outage Performance Analysis of MF-RIS-Assisted THz-NOMA Networks

Abstract

Driven by the growing demand for high-rate and reliable wireless transmission in future sixth-generation networks, enhancing the reliability of terahertz (THz) communications has become increasingly important yet challenging due to severe attenuation and blockage effects. This paper investigates the outage performance of multi-functional reconfigurable intelligent surface (MF-RIS)-assisted THz non-orthogonal multiple access networks. We establish a tractable outage analysis framework by jointly accounting for near-field transmission from the BS to the MF-RIS, generalized $\alpha-\mu$ fading, and active surface thermal noise. Since the phase-aligned cascaded channel is analytically intractable, an equivalent $\alpha-\mu$ approximation is adopted to derive outage expressions for both users under perfect and imperfect successive interference cancellation. High signal-to-noise ratio asymptotic results are further developed to characterize the corresponding reliability behavior. Numerical results verify the accuracy of the proposed analysis and demonstrate that the MF-RIS scheme outperforms conventional RIS benchmark schemes in terms of outage probability under the same total power budget. The results also provide useful insights into the effect of key system parameters on reliability.