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

10-4
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
where θ is the elevation angle (°), μ and σ are the mean and standard deviation of
ln( θ c ) , respectively, and c is a scaling factor. The values of these parameters are
summarized in Table 10-2.
Probability Density (%)
12
10
8
6
4
2
0
Lognormal Fit
0 10 20 30 40 50 60 70 80 90
Elevation (deg)
Figure 10-3: Skyline elevation angle histogram for San Antonio, Texas.
Table 10-2: Parameters associated with lognormal fits associated with histograms of the
type given in Figure 10-3 and percent visibility above 10°.
Location Mean (μ) Stand. Dev. (σ ) c
Rural Austin 0.39 0.84 2.96 98%
Suburban Austin 0.44 0.80 2.81 95%
Austin CBD 1.74 1.52 3.13 77%
San Antonio CBD 2.30 1.75 4.46 68%
Percent Visibility
Above 10°
As an another example of the useful information that may be derived employing the
measurements described above, the last column in Table 10-2 gives the percent visibility
above 10° at the various locations. We note that in the central business district of Austin
and San Antonio, only 77% and 68% of the sky are visible above 10°, respectively. The
analysis was executed assuming the binary states “blocked” or “clear.” In the following
section, a methodology is given that includes multipath effects and shadowing.