Performance analysis of active STAR-RIS-assisted NOMA with hardware impairments at finite blocklength

The active simultaneously transmitting and reflecting-reconfigurable intelligent surface's (ASTAR-RIS) potential to avoid multiplicative fading loss by utilizing integrated reflection-type amplifiers has drawn considerable interest. This paper investigates the finite blocklength (FBL) analysis of ASTAR-RIS-assisted non-orthogonal multiple access (NOMA) with perfect and imperfect successive interference cancellation (SIC) in the presence of hardware impairments over cascaded Rician fading channels. Firstly, we derive the statistical distribution of cascaded Rician fading channels with the help of Laguerre polynomial series approximation. Secondly, we derive the novel analytical expression for average block error rate (ABLER), ergodic rate (ER), and system throughput with the help of the Gauss Chebyshev quadrature and the Gauss Laguerre quadrature method. Thirdly, the asymptotic expression for ABLER is derived to gain useful insights. Finally, the Monte Carlo simulations are used to verify the analytical results. Numerical results verify the correctness and superior performance of ASTAR-RIS-assisted NOMA (ASTAR-RIS-NOMA) over passive STAR-RIS-assisted NOMA (PSTAR-RIS-NOMA) and ASTAR-RIS-assisted orthogonal multiple access (OMA) (ASTAR-RIS-OMA). Additionally, the impact of other system parameters like imperfect SIC, hardware impairments, and block length are analyzed.