Considering the practical communication environments,the outage performance and the throughput were inves-tigated for multiple reconfigurable intelligent surfaces(RIS)assisted non-orthogonal multiple access(NOMA)system with imperfect serial interference cancellation(SIC).The channel coefficients of the RIS-assisted NOMA system includ-ing the direct and the reflecting paths were approximated by Gamma distribution.An approximate closed-form expres-sions of outage probability were derived and validated through Monte Carlo simulations.The study investigated the rela-tionship between the outage performance and system parameters,including the impact of imperfect SIC,the number of RIS and the number of reflecting units.The simulation results demonstrate that,compared with the single RIS-assisted NOMA and the traditional NOMA system,the multi-RIS-assisted system achieves a 14.2 dBm gain in signal-to-noise ra-tio(SNR)for a given outage probability.Thus,employing multiple RISs can improve the outage performance and the sys-tem throughput effectively,thereby compensating for the performance degradation caused by imperfect SIC.
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