  This paper presents and compares two candidate large-scale propagation path
loss models, the alpha-beta-gamma (ABG) model and the close-in (CI) free space
reference distance model, for the design of fifth generation (5G) wireless
communication systems in urban micro- and macro-cellular scenarios. Comparisons
are made using the data obtained from 20 propagation measurement campaigns or
ray-tracing studies from 2 GHz to 73.5 GHz over distances ranging from 5 m to
1429 m. The results show that the one-parameter CI model has a very similar
goodness of fit (i.e., the shadow fading standard deviation) in both
line-of-sight and non-line-of-sight environments, while offering substantial
simplicity and more stable behavior across frequencies and distances, as
compared to the three-parameter ABG model. Additionally, the CI model needs
only one very subtle and simple modification to the existing 3GPP
floating-intercept path loss model (replacing a constant with a close-in free
space reference value) in order to provide greater simulation accuracy, more
simplicity, better repeatability across experiments, and higher stability
across a vast range of frequencies.
