Abstract:
The conflation of cognitive radio (CR) and non-orthogonal multiple access (NOMA) concepts
is a promising approach to fulfill the massive connectivity goals of future networks given the spectrum
scarcity. Accordingly, this paper investigates the performance of a cooperative CR-NOMA network in
the presence of system impairments and interference. Our analysis is involved with the derivation of
the end-to-end outage probability for primary and secondary networks by accounting for channel state
information (CSI), hardware imperfections, and residual interference caused by successive interference
cancellation errors as well as coexisting primary/secondary users. Moreover, a mathematically tractable
upper bound on spectral efficiency (SE) with its high-SNR approximations are derived. Besides, we
propose an optimal power allocation scheme for CR-NOMA users to guarantee their outage and SE
fairness. The numerical results validated by Monte Carlo simulations show that the CR-NOMA network
provides a superior outage performance over orthogonal multiple access. Furthermore, the higher level of
system imperfections leads to the performance degradation of the CR-NOMA networks. As imperfections
become more severe, the CR-NOMA is observed to deliver relatively inferior outage and SE performance
as compared to the perfect system scenario