Impacts of Imperfect SIC and Hardware Impairment on Cooperative NOMA Networks with Spectrum Sharing

Undertaking hardware impairment and imperfect successive interference cancellation (imp-SIC), this paper proposes an incremental non-orthogonal multiple access (NOMA) transmission scheme to optimize cooperative diversity for spectrum sharing cognitive radio network. In order to make full use of limited wireless resource, the primary transmitter communicates to the primary receiver directly or by the aid of the secondary source, namely, when the direct transmission between the primary transmitter and primary receiver is successful, the secondary source only transmits its own signal to the secondary destination. By deploying the selection combining (SC) scheme to combine the signals received at the primary receiver, exact closed and asymptotic form expressions for the outage probability and throughput of the primary and secondary networks are derived over Rayleigh fading channels. The results show that the outage performance is decreased with the increase of hardware impairment and the residual interference caused by imp-SIC, which means the investigation of the cognitive cooperative NOMA network is extremely significant under practical imperfect scenarios.