Figure 21 Path Loss Calculation - WaveRider LMS4000 User Manual

3 Detailed Description
You can predict the amount of path loss for each of these cases, as illustrated in
Tx O/P
Rx Threshold
As shown in Figure
• Case 1 (Unobstructed Path): Over the length of the path, the signal drops as 1/R
where R is the distance from the CCU. The range, R
distance at which the signal reaches threshold plus the desired fade margin.
• Case 2 (Path Obstructed in Vicinity of EUM): From the CCU, the signal initially
drops as 1/R
these obstructions, the signal drops more steeply than it does in the unobstructed
case, more like 1/R
which the signal reaches threshold plus the desired fade margin. As shown above,
R < R
case2
you would expect to be able to serve EUMs that are farther from the CCU, and to
provide better fade margin to those that are in closer.
• Case 3 (Path Obstructed in Vicinity of CCU): From the CCU, the signal initially
drops as 1/R
CCU. Once the signal leaves these obstructions, it drops as 1/R
of the path is clear. Once again, the range R
which the signal reaches threshold plus the desired fade margin. As shown above,
R < R
case3
case; however, it is always true that the margin is greater for Case 2 than Case 3, in
the coverage area indicated by the shading in
successful indoor installs is likewise higher for Case 2 than Case 3.
34
Case 3
Path Obstructed
in Vicinity of CCU
Figure 21 Path Loss Calculation
21, the path loss for each case is quite different:
2
until it reaches the obstructions in the vicinity of the EUM. Through
4
. Once again, the range, R
, which intuitively makes sense. If the path to the EUM is unobstructed,
case1
4
until it leaves the obstructing clutter and terrain in the vicinity of the
. Although it shows R
case1
Probability of successul indoor installation is
greater for Case 2 than for Case 3, in this
region
Case 1
Unobstructed Path
Free Space Loss
Case 2
Path Obstructed
in Vicinity of EUM
Fade Margin
R R
case 3 case 2
, is determined by the
case1
, is determined by the distance at
case2
, is determined by the distance at
case3
< R , this may or may not always be the
case3 case2
Figure 21. In this area, the probability of
Figure 21.
R
Range
case 1
2
,
2
since the remainder
APCD-LM043-4.0