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

8-28
Slope of Signal Level (dB/MHz)
0.006
0.004
0.002
0.000
-0.002
-0.004
-0.006
-0.008
-0.010
-0.012
COMMONS
EERL
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
FARMHOUSE
HOUSE
Building
Figure 8-19: Summary of trend slope statistics in the six building.
MER
±1.96*Std. Dev.
±1.00*Std. Dev.
Mean
MOTEL
The autocorrelation of frequency variability reveals information regarding systems which
attempt to mitigate fading employing power control on the uplink (mobile to satellite) at
one frequency using knowledge of the fade on the downlink (satellite to mobile) at
another frequency. An example of the autocorrelation at a given receiver location is
plotted for each building in Figure 8-20. At 500 MHz, the lag of 10, for example, implies
a bandwidth separation of 10 x 0.002 x 500 MHz = 10 MHz. At 3000 MHz, the lag of 10
implies a bandwidth separation of 60 MHz. The lag of 10 gives an autocorrelation of
approximately 0.6 for the Farmhouse and 0.1 for the motel (extremes). Table 8-16
summarizes the median decorrelation bandwidths (decorrelation = e -1 = 0.37) when all
positions are accounted for within each of the buildings. The overall average of the
median decorrelation is 2.4% of the frequency for the case in which the farmhouse is not
included and 5.4% when the farmhouse is included.