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LEVEL CROSSING RATE (# crossing / sec)
100.00
10.00
1.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
LEVEL RELATIVE TO MEAN (dB)
Figure 3-11: Measured vs. Theoretical LCR
♦ ♦ ♦ ♦ Measured
_ _ _ _ _ Theoretical
3.6.2.
Rician Fading Amplitude Distribution
Rician fading is formed by the sum of a Rayleigh distributed signal and a Line-Of-Site
(LOS or direct path) signal, where the LOS signal is typically subjected to a static
frequency shift (static Doppler). A fading environment typically associated with Rician
fading is that where one strong direct path reaches the receiver at roughly the same
delay as multi-path from local scatterers.
The SR5500 supports the general case of Rician fading with programmable Angle of
Arrival (AOA) and K factor. In the general case of Rician fading the arrival angle of the
LOS path at the receiver is programmable, as is the ratio of power between the LOS path
and the multi-path. The SR5500 provides access to both the LOS arrival angle specified
as the AOA (expressed in degrees) and the LOS path to multi-path power ratio specified
as the K factor (expressed in dB). Changing the LOS arrival angle will move the relative
location of the direct path with respect to the faded spectrum by changing the static
Doppler shift of this component. This Doppler shift is set according to the following
equation:
Doppler direct component = Doppler faded component x cosine (LOS arrival angle)
The K factor setting then controls the relative power of the direct path and the multi-path
and has a valid range of -30dB (faded spectrum will dominate) to +30dB (LOS signal will
dominate).