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In this paper, intelligent reflecting surface (IRS)-assisted orbital angular momentum (OAM) with non-orthogonal multiple access (NOMA) under imperfect successive interference cancellation (SIC) and imperfect channel state information (CSI) is proposed. Importantly, the communication links of both cell-center user (CCU) and cell-edge user (CEU) are developed through IRS when they are in the non-line-of-sight (NLoS) of the transmitter. The aim of developing the proposed system is the accommodation of massive connectivity and enhancement of sum capacity as well as user capacities with the help of NOMA. The performance of the proposed IRS-OAM-NOMA system is evaluated and compared with the existing techniques such as IRS-assisted OAM with orthogonal multiple access (OMA) OMA-OAM-IRS and NOMA-IRS. The simulation results show that the proposed IRS-OAM-NOMA system outperforms the existing techniques in terms of user capacity and sum capacity under ideal conditions and with imperfect successive interference cancellation (SIC) and imperfect channel state information (CSI). [ABSTRACT FROM AUTHOR]

In this paper, the outage performance of uplink intelligent reflecting surface (IRS)-aided non-orthogonal and orthogonal multiple-access (NOMA/OMA) networks is investigated. Specifically, we consider a two-user equipment (UE) NOMA/OMA network, in which both UEs have both direct (UE → base station (BS)) and reflected (UE → IRS → BS) links. All the links between the UEs and the IRS/BS are modeled either as a Rayleigh or a Nakagami- m variate. To characterize these networks' outage performance, new statistics for the effective channel gains of the IRS-NOMA/OMA's UEs are derived. Based on that, closed-form expressions for the outage probability (OP) for each UE are derived. Monte Carlo simulations' results are provided to verify the accuracy of the analytical results. [ABSTRACT FROM AUTHOR]