Ergodic Rate Analysis of STAR-RIS-NOMA Aided Vehicular Networks Under TS and ES Protocols

This paper explores a vehicular scenario to investigate the ergodic rate performance of simultaneously transmitting and reflecting-reconfigurable intelligent surface (STARRIS) assisted non-orthogonal multiple access (NOMA) networks. A moving access point sends the information to near and far vehicles through reflection and transmission, respectively, via STAR-RIS equipped vehicles over double Rayleigh fading channels. We derive ergodic rates of STAR-RIS assisted NOMA networks using two different STAR-RIS modes of operation: time switching (TS) and energy splitting (ES) protocols. We also derive asymptotic ergodic rate expressions at high SNR regimes for each NOMA user under both TS and ES protocols. Finally, the correctness of derived analytical ergodic rate expressions is validated via Monte-Carlo simulations. It is demonstrated that the considered system achieves higher ergodic rates under ES protocol than that of TS protocol for both near and far users.