Performance Analysis of STAR-RIS-Aided RSMA System With Hardware Impairment

The performance of a simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided rate splitting multiple access (RSMA) system is analyzed over κ-μ fading channel, where the transceiver hardware impairment and STAR-RIS phase error are both considered. Based on the performance analysis, the signal-to-interference-plus-noise ratios of the users are derived, followed by an approximated closedform expression for the outage probability (OP). An optimization scheme for the power allocation (PA) coefficients is formulated to minimize the OP, and a closed-form expression for the optimal PA is derived. Simulation results show the effectiveness of the theoretical analysis and PA scheme, and reveal that the system with the proposed PA scheme has lower OP than that with the conventional fixed PA. Besides, the system performance degrades due to the effect of hardware impairment and/or phase errors.