MEMORANDUM
Date
Our reference
Page
Dec 15, 2011
Dnr:
1(6)
S5
Ola Wimo; Jesper Simons
[email protected]; [email protected]
Some power link calculations for DA2GC –
different antenna scenarios 2450MHz
Single aggressor case
Original scenario from document SE44(11)024
Relevant parameters DA2GC, RLAN from doc SE44(11)024
Transmit power: 22.92 dBm
Transmit peak gain: 10.07 dBi
Interfering relative gain: -2.44 dB
Victim peak gain: 3 dBi
Victim relative gain (what is this?): -3 dB
Path loss: 124.83 dB (including gas attenuation, pure free space loss is 120.18
dB)
EIRP=22.92+10.07 = 32.99 [dBm]
Interfering power = EIRP-interfering relative gain-pathloss + victim peak gain
– victim relative gain= -94.28 dBm
RLAN receiver sensitivity = -82 dBm
→ C/I = 12.28 dB
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Worst case victim antenna
Transmit power: 22.92 dBm
Transmit peak gain: 10.07 dBi
Interfering relative gain: -2.44 dB
Victim peak gain: 3 dBi
Victim relative gain (what is this?): 0 dB
Path loss: 124.83 dB (including gas attenuation, pure free space loss is 120.18
dB)
EIRP=22.92+10.07 = 32.99 [dBm]
Interfering power = EIRP-interfering relative gain-pathloss + victim peak gain
– victim relative gain= -91.28 dBm
RLAN receiver sensitivity = -82 dBm
→ C/I = 9.28 dB
Worst case aggressor antenna
Transmit power: 22.92 dBm
Transmit peak gain: 10.07 dBi
Interfering relative gain: 0 dB
Victim peak gain: 3 dBi
Victim relative gain (what is this?): -3 dB
Path loss: 124.83 dB (including gas attenuation, pure free space loss is 120.18
dB)
EIRP=22.92+10.07 = 32.99 [dBm]
Interfering power = EIRP-interfering relative gain-pathloss + victim peak gain
– victim relative gain= -91.84 dBm
RLAN receiver sensitivity = -82 dBm
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→ C/I = 9.84 dB
Worst case victim and aggressor antenna
Transmit power: 22.92 dBm
Transmit peak gain: 10.07 dBi
Interfering relative gain: 0 dB
Victim peak gain: 3 dBi
Victim relative gain (what is this?): 0 dB
Path loss: 124.83 dB (including gas attenuation, pure free space loss is 120.18
dB)
EIRP=22.92+10.07 = 32.99 [dBm]
Interfering power = EIRP-interfering relative gain-pathloss + victim peak gain
– victim relative gain= -88.84 dBm
RLAN receiver sensitivity = -82 dBm
→ C/I = 6.84 dB
Worst case victim and aggressor antenna. Victim 10 dBi antenna gain.
Transmit power: 22.92 dBm
Transmit peak gain: 10.07 dBi
Interfering relative gain: 0 dB
Victim peak gain: 10 dBi
Victim relative gain (what is this?): 0 dB
Path loss: 124.83 dB (10 km)
EIRP=22.92+10.07 = 32.99 [dBm]
Interfering power = EIRP-interfering relative gain-pathloss + victim peak gain
– victim relative gain= -81.84 dBm
RLAN receiver sensitivity = -82 dBm
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→ C/I = -0.16 dB
Eight aggressor case. Evenly spaced transmitters
Figure: Illustration of a multi aggressor case
Transmitter height
[meters]
Radial distance
[meters]
Total distance
[meters]
Free space loss
[dB] (no
gaseous
attenuation)
10000
1000
10050
FSL1 = 120.22
10000
3000
10440
FSL2 = 120.56
10000
5000
11180
FSL3 = 121.15
10000
7000
12207
FSL4 = 121.92
10000
9000
13454
FSL5 = 122.76
10000
11000
14866
FSL6 = 123.63
10000
13000
16401
FSL7 = 124.48
10000
15000
18028
FSL8 = 125.30
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Transmit power: 22.92 dBm
Transmit peak gain: 10.07 dBi
Interfering relative gain: 0 dB
Victim peak gain: 3 dBi
Victim relative gain: -3 dB
EIRP=22.92+10.07 = 32.99 [dBm]
Interfering power = EIRP-interfering relative gain-pathloss + victim peak gain
– victim relative gain [dBm]
Transmitter
Interfering power [dBm]
(not including gaseous
attenuation)
C/I (values will be
somewhat better
when gaseous
attenuation is
included)
1
-87.23
5.23
2
-87.57
5.57
3
-88.16
6.16
4
-88.93
6.93
5
-89.77
7.77
6
-90.64
8.64
7
-91.49
9.49
8
-92.31
10.31
Transmitter 1-8
aggregated
-80.15
1,85
When the maximum number of transmitters are aggregated the total interfering
power yields a C/I of 1.85 dB.
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Conclusion
Single aggressor case
Protection (C/I)
Transmit antenna
Receive antenna
C/I = 12.28 dB
Not worst case
Not worst case
C/I = 9.28 dB
Not worst case
Worst case
C/I = 9.84 dB
Worst case
Not worst case
C/I = 6.84 dB
Worst case
Worst case
C/I = -0.16 dB
Worst case
Worst case (10 dBi
antenna, see doc
SE44(11)019)
From the above table one can see that the only scenario where a wireless router
(RLAN) can operate within the specified protection is when none of the
antennas are aligned.
Eight (maximum number) aggressor case
In the aggregated scenario it is clear that the RLAN will suffer from severe
interference.
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