coverage input analysis
it is one of the most important step in any dimensioning process is defining the input data.
Link Budget losses:
the first main step which we calculate losses which be a part of MAPL(Max Allowable Path Loss)
there are different types of losses we have to consider for effective reliable dimensioning process
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Cable losses :
the sum of all signal losses caused by the antenna line outside the base station cabinet ,it contain the following losses:
-feeder loss: it depends on the feeder diameter and the length of feeder.
loss (0.5 inch diameter )=feeder length*0.11
loss (7/8 inch diameter)=feeder length *0.65
loss(1.25 inch diameter)=feeder length*0.047
loss (1.625 inch diameter)= feeder length *0.0371
-cabinet Jumper loss: it depends on the cabinet jumper length and the diameter of the cable and number of cabinet.
loss (0.5 inch diameter )=cabinet jumper length*number of Cabinet jumper*0.181
loss (7/8 inch diameter)= cabinet jumper length*number of Cabinet jumper*0.065
-Jumper loss : it also depends on jumper diameter , it's length and the number of jumper used.
loss (0.5 inch diameter )=jumper length*number of jumper*0.181
loss (7/8 inch diameter)= jumper length*number of jumper*0.065
-TMA &MHA losses: if this solution is implemented, there are losses due to insertion and it is in the range of 0.5dB.
-Connector loss: it is looses due to insertion the connector and it is within the range of 0.5dB for each connector.
penetration losses :
it is the signal attenuation due to obstacles in the way between TX antenna and RX antenna like buildings and cars...etc. this loss depends on the cluster type and the frequency band used in planning process as shown
Body losses :
the human body has several negative effects on the UE performance. generally the Body loss not applied to data services and it is only in Circuit switching system and it is within the range of 3dB.
Link Budget margins:
the next step after calculation losses is to calculate system margin which consists of two main types of margins as following
interference margins :
interference margins refer to noise rise which is related with cell radius ,frequency planning and system load. also it result from the neighbor cell interference which is increase with system load increase.
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Shadowing margins :
the signal strength value predicted by the wave propagation Model algorithm can be considered as a mean value for signal strength for small area . also due to obstacles and the signal take more than one path till reach user there are several images of signal at the RX so may be the summation of the received signal is below the sensitivity so we have to take the effect of multipath fading in our planning to ensure that the signal will reach RX above the sensitivity and RX can receive it.
values of the shadowing margin depends on the probability of cell as shown in table 2
as probability of coverage increase the more shadowing (SLOW FADING MARGIN)
Dense
Urban
|
Urban
|
Sub
urban
|
rural
|
|
85
%
|
3.2
|
3.2
|
3.2
|
2.4
|
90%
|
5.5
|
5.5
|
5.5
|
4.3
|
91%
|
5.9
|
5.9
|
5.9
|
4.8
|
92%
|
6.5
|
6.5
|
6.5
|
5.4
|
93%
|
7.2
|
7.2
|
7.2
|
5.9
|
94%
|
7.9
|
7.9
|
7.9
|
6.5
|
95%
|
8.6
|
8.6
|
8.6
|
7.2
|
96%
|
9.6
|
9.6
|
9.6
|
8.1
|
97%
|
10.7
|
10.7
|
10.7
|
9.1
|
98%
|
12.2
|
12.2
|
12.2
|
10.4
|
99%
|
14.6
|
14.6
|
14.6
|
12.3
|
100%
|
21.3
|
21.3
|
21.3
|
19.2
|
check the other parts for the 3G Network Planning in details