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

8-6
SIGNAL LEVEL (dB)
4
2
0
-2
-4
-6
-8
-10
-12
-14
-16
-18
-20
-22
-24
1%
10%
50%
90%
99%
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0
FREQUENCY (GHz)
Figure 8-3: Cumulative probabilities of relative signal level as a function of frequency
for Site 2. The database reflects measurements taken at 16 positions for 80 cm vertical
scans at several locations and seven bandwidths
The cumulative distributions of the relative dB signal losses were found to follow a
Gaussian distribution for the cases in which the loss values were binned for the composite
of values. The composite of values were obtained at the different frequencies and at the
different locations within a particular building (from 8 to 20 locations were considered
within a given building). In Table 8-3 are given the mean and standard deviations
associated with the best-fit Gaussian distributions for each of the sites (building
locations) at defined “average” and “best” cases. The “average” case was obtained by
taking the linear average loss over a series of bandwidths ranging from 1 MHz to 90 MHz
(1, 2, 5, 9, 15, 45, and 90 MHz) within each 100 MHz bin interval over the frequency
span 700 MHz to 1800 MHz. In determining the “average” the results were also
combined for each of 16 antenna positions (5 cm displacement per position) and at each
location within a given site (eight to twenty locations per site). The “best” case
corresponds to statistics associated with that location within the position scan that
resulted in the smallest losses. Site 6 showed the largest mean loss of approximately
-25 dB as this building was a mobile trailer with a sheet metal exterior and aluminum
frame windows having metal screens. At all other locations, the measurements of Vogel
and Torrence were obtained in a less severe attenuation environment. Neither Ricean nor