  In this paper, we study an unmanned aerial vehicle (UAV)-aided non-orthogonal
multiple access (NOMA) multi-way relaying networks (MWRNs). Multiple
terrestrial users aim to exchange their mutual information via an
amplify-and-forward (AF) UAV relay. Specifically, the realistic assumption of
the residual hardware impairments (RHIs) at the transceivers is taken into
account. To evaluate the performance of the considered networks, we derive the
analytical expressions for the achievable sum-rate (ASR). In addition, we carry
out the asymptotic analysis by invoking the affine expansion of the ASR in
terms of \emph{high signal-to-noise ratio (SNR) slope} and \emph{high SNR power
offset}. Numerical results show that: 1) Compared with orthogonal multiple
access (OMA), the proposed networks can significantly improve the ASR since it
can reduce the time slots from $\left[ {\left( {M - 1} \right)/2} \right] + 1$
to 2; and 2) RHIs of both transmitter and receiver have the same effects on the
ASR of the considered networks.
