  This paper presents key parameters including the line-of-sight (LOS)
probability, large-scale path loss, and shadow fading models for the design of
future fifth generation (5G) wireless communication systems in urban
macro-cellular (UMa) scenarios, using the data obtained from propagation
measurements at 38 GHz in Austin, US, and at 2, 10, 18, and 28 GHz in Aalborg,
Denmark. A comparison of different LOS probability models is performed for the
Aalborg environment. Alpha-betagamma and close-in reference distance path loss
models are studied in depth to show their value in channel modeling.
Additionally, both single-slope and dual-slope omnidirectional path loss models
are investigated to analyze and contrast their root-mean-square (RMS) errors on
measured path loss values. While the results show that the dual-slope
large-scale path loss model can slightly reduce RMS errors compared to its
singleslope counterpart in non-line-of-sight (NLOS) conditions, the improvement
is not significant enough to warrant adopting the dual-slope path loss model.
Furthermore, the shadow fading magnitude versus distance is explored, showing a
slight increasing trend in LOS and a decreasing trend in NLOS based on the
Aalborg data, but more measurements are necessary to gain a better knowledge of
the UMa channels at centimeter- and millimeter-wave frequency bands.
