lly based on measurements. A typical value for o is 8 dB. The parameters that statistically describe path loss due to large-scale fading (macro- scopic fading) for an arbitrary location with a specific transmitting-receiving antenna sepa- ration include the reference distance do, the path loss exponent n, and the standard deviation o of X [33]. Microscopic fading refers to the rapid fluctuations of the received signal in time and frequency and is caused by scattering objects between the transmitting and receiving antennas. When the received RF signal is a superposition of independent scattered compo- nents plus an LoS component, the envelope of the received signal r(t) has a Rician Probability Distribution Function (PDF) that is referred to as Rician fading. As the 290 Chapter 3 magnitude of the LoS component approaches zero, the Rician PDF approaches a Rayleigh PDF. Thus where K and Io(r) denote the Rician factor and zero-order modified Bessel function of the first kind. 2 In the absence of LoS path (K = 0), the Rician PDF reduces to Rayleigh distribution. One of the challenges of mobile communications in the higher frequency bands for outdoor access has been to overcome the difficulties in highly varying propagation conditions. Understanding the propagation conditions will be critical to designing an appropriate air interface and determining the type of hardware (particularly the array size) needed for reli- able communications. Extensive measurements over a wide range of frequencies were per- formed by a large number of academic institutions and the industry. Since maintaining link budgets at higher frequencies are challenging, there are few measurements at larger dis- tances for 5G deployment scenarios of interest. Based on the results of the measurements, some important observations were made that helped development of the new channel mod- els. The most notable signal degradation is due to the higher path loss of the bands above 6 GHz relative to sub-6 GHz bands. The additional path loss as result of increas