ovides more consistency with measured data and the error between the measured data and the 3GPP LoS probability model over all distances are small. Note that the 3GPP UMi LoS probability model is not a function of UE height unlike the UMa LoS probability model. New Radio Access Physical Layer Aspects (Part 1) 303 d2D-out d2D-in Outdoor scenario Indoor scenario Figure 3.5 Definition of 2D and 3D distances in outdoor/indoor environments [4]. RMa (021) UMa (O2I) UMi (O2I) InH-Office (NLOS) RMa (NLOS) UMa (NLOS) UMi (NLOS) InH-Office (NLOS-opt) RMa (LOS) UMa (NLOS-opt) UMi (NLOS-opt) InH-Office (LOS) UMa (LOS) UMi (LOS) InH-Shopping mall (LOS) 3D distance (m) Figure 3.6 Path loss with (solid line) and without (dashed line) shadowing for various scenarios [37]. In the path loss models we often refer to 2D and 3D distances. Those distances are defined as follows (see Fig. 3.5): Fig. 3.6 shows the path loss in dB for the 3D distance from the smallest value supported in each scenario to 103 m for the outdoor scenarios and 102 m for the indoor cases. In this fig- ure, O2I denotes outdoor-to-indoor loss in various test environments. 3.1.2 Two- and Three-Dimensional Channel Models The 5G cellular systems are expected to operate over a wide range of frequencies from 450 MHz to 100 GHz. For the development and standardization of the new 5G systems operating in frequency bands above 6 GHz, there was a serious need to accurately model radio signal propagation in these frequency bands, which could not be fully characterized by the existing channel models, because the previous generations of channel models were designed and evaluated for sub-6 GHz frequencies. The development of 3GPP 3D channel 304 Chapter 3 model was a step toward modeling 2D antenna arrays that are used in 5G network deploy- ments. The measurements indicate that the smaller wavelengths increase the sensitivity of the propagation models to the scale of the environment effects and show some frequency depen- dence of the path loss as well as increased occurrence o