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

10-8
10.5 Urban Three-State Fade Model (UTSFM)
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
Employing concepts described in Section 10.4, an Urban Three-State Fade Model was
developed by Akturan and Vogel [1997]. This model, hereafter referred to by the
acronym UTSFM, has the form
fν ( ν, α ) = C( α ) f Rice( ν) + S( α ) f Loo( ν) + B( α) fLoo(
ν)
, (10-8)
where in (10-8) is the elevation angle. Using photogrammetric measurements in urban
Japan, henceforth generically referred to as “Tokyo” although other Japanese cities were
also involved, Akturan and Vogel [1997] have characterized C, S, B as a function of α .
These values, which have been averaged over the 360° azimuth, are tabulated in Table
10-4. In Figure 10-5 are plotted a family of CDF’s employing (10-8), the values in Table
10-4 at the mid-range of the angular intervals, and the parameters in the right-hand
column of Table 10-3. We note the dramatic effect elevation angle has on fade at any
given fixed exceedance probability level. For example, at the 10% level, the fades range
between approximately 6 dB at 82° and 28 dB at 7°. Between 12° and 67° at the 10%
level, the fade increases at a rate of approximately 0.2 dB per degree (e.g., from 15 dB to
25.5 dB). All the curves in Figure 10-5 contain a terraced shape region between
approximately 5 to 13 dB where a relatively small percentage change takes place. Such a
result indicates that increasing the fade margin beyond approximately 5 dB may not “pay
off” until 13 dB is exceeded. The curves in Figure 10-5 may be employed at any urban
location (for L-Band) under the assumption that the path-state mixture vector is given by
(10-7), implying the urban environment of Tokyo is similar to the urban location being
modeled.
Table 10-4: Tabulation of azimuth averaged values of C, S and B in (10-8) for different
elevation angle intervals for Tokyo, Japan.
Elevation Angle
Interval (°)
C S B
Elevation Angle
Interval (°)
C S B
0-4 0.02 0.03 0.95 45-49 0.67 0.05 0.27
5-9 0.07 0.06 0.86 50-54 0.72 0.05 0.23
10-14 0.17 0.08 0.75 55-59 0.76 0.04 0.20
15-19 0.28 0.08 0.64 60-64 0.80 0.03 0.17
20-24 0.37 0.08 0.56 65-69 0.83 0.03 0.14
25-29 0.44 0.07 0.48 70-74 0.86 0.03 0.11
30-34 0.51 0.07 0.42 75-79 0.89 0.02 0.09
35-39 0.58 0.06 0.36 80-84 0.92 0.02 0.06
40-44 0.63 0.06 0.31 85-89 0.93 0.02 0.06