  This paper investigates the performance of Multiple-input multiple-output
non-orthogonal multiple access (MIMO-NOMA) systems with randomly deployed
users, where the randomly deployed NOMA users follow Poisson point process
(PPP), the spatial correlation between MIMO channels are characterized by using
Kronecker model, and the composite channel model is used to capture large-scale
fading as well as small-scale fading. The spatial randomness of users'
distribution, the spatial correlation among antennas and large-scale fading
will severally impact the system performance, but they are seldom considered in
prior literature for MIMO-NOMA systems, and the consideration of all these
impact factors challenges the analysis. Based on zero-forcing (ZF) detection,
the exact expressions for both the average outage probability and the average
goodput are derived in closed-form. Moreover, the asymptotic analyses are
conducted for both high signal-to-noise ratio (SNR) (/small cell radius) and
low SNR (/large cell radius) to gain more insightful results. In particular,
the diversity order is given by $\delta = {{N_r} - {M} + 1}$, the average
outage probability of $k$-th nearest user to the base station follows a scaling
law of $O\left({D^{\alpha \left( {{N_r} - {M} + 1} \right) + 2k}}\right)$, the
average goodput scales as $O({D^{2}})$ and $O({D^{-2}})$ as $D \to 0$ and $D
\to \infty$, respectively, where $N_r$, $M$, $\alpha$ and $D$ stand for the
number of receive antennas, the total number of data streams, the path loss
exponent and the cell radius, respectively. The analytical results are finally
validated through the numerical analysis.
