Handbook of Propagation Effects for Vehicular and ... - Courses

Table of Contents
5 Fade and Non-Fade Durations and Phase Spreads_________________________ 5-1
5.1 Background _________________________________________________________ 5-1
5.2 Concept of Fade and Non-Fade Durations ________________________________ 5-1
5.3 Fade Durations Derived from Measurements in Australia ___________________ 5-3
5.3.1 Experimental Aspects ____________________________________________________ 5-3
5.3.2 Fade Duration Model_____________________________________________________ 5-3
5.4 Fade Duration Measurements in Central Maryland ________________________ 5-6
5.5 Fade Duration Distributions at Higher Elevation Angles ____________________ 5-7
5.6 Summary of Fade Duration Results______________________________________ 5-8
5.7 Cumulative Distributions of Non-Fade Durations: Australian Measurements__ 5-10
5.8 Cumulative Distributions of Non-Fade Duration: Central Maryland _________ 5-11
5.9 Cumulative Distributions of Phase Fluctuations: Australian Measurements ___ 5-11
5.10 Summary and Recommendations ____________________________________ 5-14
5.11 References _______________________________________________________ 5-14
Table of Figures
Figure 5-1: Idealized scenario showing line of roadside trees (top) and relative signal levels
(bottom) for the case in which a vehicle receiving satellite signals drives parallel to the
roadside trees and the line-of-sight ray to the satellite intersects the tree canopies. ......................... 5-2
Figure 5-2: Best fit exponential fade distributions of the form (5-3) derived from measurements in
south-eastern Australia along road types classified as “moderate” and “extreme.”
Measurements were made at L-Band (1.5 GHz) at an elevation of 51°. Also shown is the
EERS model distribution. ............................................................................................................. 5-4
Figure 5-3: Best fit lognormal distribution (5-1) of fade duration distances for a 5-dB threshold.
The distribution (1.5 GHz, elevation = 51°) encompasses road types which exhibit “moderate”
and “extreme” shadowing and is plotted against logarithmic scales................................................ 5-6
Figure 5-4: Fade durations (1.5 GHz) at elevation angles of 30°, 45°, and 60° for tree-lined road in
central-Maryland [Goldhirsh and Vogel, 1989]. The probability is conditioned to a 5 dB fade
threshold. ..................................................................................................................................... 5-7
Figure 5-5: Fade duration distributions at 1.3 GHz derived from measurements of Sforza and
Buonomo [1993] in North Yorkshire, U.K. for a “wooded” environment....................................... 5-8
Figure 5-6: Fade durations from different investigations (Figure 5-3 through Figure 5-5) shown
together........................................................................................................................................ 5-9
Figure 5-7: Best fit power curves (5-6) showing non-fade duration distributions for a 5 dB threshold
for road types which exhibit “moderate” and “extreme” shadowing............................................. 5-11
5-i