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 in Austin, US, and Aalborg, Denmark, at 2, 10, 18, and 38 GHz. A comparison of different LOS probability models is performed for the Aalborg environment. 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 dual-slope model can slightly reduce RMS errors compared to their single-slope counterpart in non-line-of-sight conditions, the improvement is not significant enough to warrant adopting the dual-slope model. Additionally, alpha-beta-gamma and close-in reference distance path loss models are studied in depth to show their value in channel modeling. Furthermore, the shadow fading spread versus distance remains unclear based on the current measurement results, thus more measurements are necessary to gain a better knowledge of the UMa channels at centimeter- and millimeter-wave frequency bands.
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