  In this paper, we propose a unified framework to analyze the performance of
dense small cell networks (SCNs) in terms of the coverage probability and the
area spectral efficiency (ASE). In our analysis, we consider a practical path
loss model that accounts for both non-line-of-sight (NLOS) and line-of-sight
(LOS) transmissions. Furthermore, we adopt a generalized fading model, in which
Rayleigh fading, Rician fading and Nakagami-m fading can be treated in a
unified framework. The analytical results of the coverage probability and the
ASE are derived, using a generalized stochastic geometry analysis. Different
from existing work that does not differentiate NLOS and LOS transmissions, our
results show that NLOS and LOS transmissions have a significant impact on the
coverage probability and the ASE performance, particularly when the SCNs grow
dense. Furthermore, our results establish for the first time that the
performance of the SCNs can be divided into four regimes, according to the
intensity (aka density) of BSs, where in each regime the performance is
dominated by different factors.
