@月命卡等 Modeling channels by mechanism [Medbo et al. 2012] Classification of paths as diffracted or specularly reflected done by means of the projected UE location h,which is [aap] obtained by extrapolating the estimat- ed wave direction at the base station to the distance corresponding to the esti- mated delay. If h is on or near ground level,the wave is classified as specular If h is significantly above ground,e.g. more than half of the height of the clos- est obstructing building,then the path [p]oe is classified as diffracted For this measurement the radio link at UE locations for which the excess loss 400 600 800 Rel.power is larger than 25 dB has a significant Propagation distance [m] [dB] contribution from diffracted paths. Figure 3.Power distributions in elevation angle and propagation distance for UE locations having excess loss less than 25 dB (upper)and higher than 25 dB(lower).Projected UE heights of -6.5,0 and 6.5 m above ground are indicated with solid lines. Graduate course:Propagation Channel Characterization,Parameter Estimation and Modeling 64/199 Modeling channels by mechanism [Medbo et al. 2012] Graduate course: Propagation Channel Characterization, Parameter Estimation and Modeling 64 / 199 ■ Classification of paths as diffracted or specularly reflected done by means of the projected UE location h, which is obtained by extrapolating the estimat￾ed wave direction at the base station to the distance corresponding to the esti￾mated delay. ■ If h is on or near ground level, the wave is classified as specular ■ If h is significantly above ground, e.g. more than half of the height of the clos￾est obstructing building, then the path is classified as diffracted ■ For this measurement the radio link at UE locations for which the excess loss is larger than 25 dB has a significant contribution from diffracted paths. extrapolating the estimated wave direction at the base station to the estimated delay. If the projected UE location is on or near ground level, the wave has whereas if the projected UE location is significantly above ground, e.g. more than half of the height of the closest obstructing building, then the path is rresponding power distributions ce for the two sets of UE locations are shown in Fig. 5. It is clear that only for the UEs having excess loss larger than 25 dB there is significant power for projected UE heights larger than 6.5 m. This is also confirmed by comparing the diffracted fraction of total power vs UE locations and excess loss shown in Fig. 4. In order to get an impression of the overall distribution of Fraction of total power classified as diffracted versus excess Rel. power [dB] Propagation distance [m] Elevation angle [deg] Elevation angle [deg] Figure 3. Power distributions in elevation angle and propagation distance for UE locations having excess loss less than 25 dB (upper) and higher than 25 dB (lower). Projected UE heights of -6.5, 0 and 6.5 m above ground are indicated with solid lines