interference analysis (ko)
TRANSCRIPT
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In-Building Coverage System
Interferences Analysis
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Agenda
System Specification
Categories of Interferences in In-Building System
Noise and Base Station Sensitivity
Spurious Emission AnalysisIntermodulation Analysis
Interference Analysis Conclusion
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System Specification
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System Specification
5 systems combined into one in-building system
Trunk800: 806-821/uplink, 851-866/downlink
CDMA800: 825-835/uplink, 870-880/downlink
GSM900: 885-915/uplink, 930-960/downlink
DCS1800: 1705-1780/uplink, 1805-1880/downlink
WCDMA: 1920-1980/uplink, 2110-2170/downlink
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Categories of Interferences in In-Building System
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Categories of Interferences inIn-Building System
Inter-systems interferences involved in in-buildingsystem
Receiver BlockingSpurious Emissions
Inter-modulation
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Frequency band Issues of CDMA800
and EGSM900
Power
Frequency
CDMA800 GSM900
870-880(downlink)
885-915
(uplink)
Very close between CDMA downlinkand EGSM uplink.
To avoid the inter-frequency bandinterference requires highperformance filter.
This kind of filter is too heavy andlarge to install in a true project even ifit can be researched and produced.
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Noise
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K is Boltzmanns constant = 1.38 X 10-23 J/K
T is the absolute temperature in Kelvin = 290 (17o C)
B is the Bandwidth in Hz = 3.84 x 106 (WCDMA)
Nf is the Noise figure of receiver = RBS(without ASC) = 5dB (3.1)
NRBS = 10log [(1.38 X 10-23 X 290 X 3.84 X 106 X3.1)/10-3]dBm
= -103 dBm
N = 10 log (KTBNf) dBm
Thermal Noise (N)
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=> Irx-max = - 103 -6.9 = -109.9 (WCDMA)
Irx-max = -109.9 [dBm/3.84 MHz]
Max allowed degradation = 0.8 dB
=> 0.8 = 10 log (1+ Irx-NoiseFloor)
=> Irx-NoiseFloor = 100.08-1
= 0.2023
= -6.9dB
Maximum allowed RBS
Sensitivity degradation
4.76
03
-6.90.8
-9.10.5
-16.30.1
Irx-NoiseFloor [dB]Sensitivity degradation due to Irx
[dB]
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Maximum allowed RBSSensitivity degradation
-98.4-111.3-111.3-103.4-120.34.76
-103.1-116-116-108.1-12503
-110-122.9-122.9-115-131.9-6.90.8
-112.2-125.1-125.1-117.2-134.1-9.10.5
-119.4-132.3-132.3-124.4-141.3-16.30.1
-103-116-116-108-125Noise Floor
WCDMADCS1800GSM900CDMA800Trunk800
[3.84MHz][0.2MHz][0.2MHz][1.23MHz][0.025MHz]
Irx_maxIrx_maxIrx_maxIrx_maxIrx_maxIrx-NoiseFloor
[dB]
Sensitivity
degradation dueto Irx [dB]
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Spurious Emissions Analysis
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WCDMA SpuriousEmissions Limits (3GPP)
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WCDMA Spurious Emissions
Drop into other Frequency Band
100 kHz-98dBm17101785DCS1800
100 kHz-98dBm876915GSM900
100kHz-98dBm825835CDMA800
100kHz-36dBm806821Trunk800
Measurement
Bandwidth
Noise LevelSystem Bandwidth
(MHz)
Affected
system
200 kHz-9517101785DCS1800
200 kHz-95890915GSM900
1.23 MHz-87825835CDMA800
25 kHz-42806821Trunk800
BandwidthNoise LevelSystem Bandwidth
(MHz)
Affected
system
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Isolation between WCDMA andother systems when co-location
28DCS1800
28GSM900
28CDMA800
90Trunk800
WCDMA
dB
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Conclusion: Isolation Dueto Spurious Emissions
30308690WCDMA
28288690DCS1800
28289090GSM900
28757590CDMA800
90757590Trunk800
WCDMADCS1800GSM900CDMA80
0Trunk800
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Intermodulation Analysis
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IM2 Products
WCDMAGSM900GSM900
DCS1800CDMA800TRUNK800
DCS1800TRUNK800TRUNK800
GSM900GSM900DCS1800
Interfered Systemf2f1
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IM3 Products
CDMA800CDMA800TRUNK800
GSM900TRUNK800CDMA800
TRUNK800GSM900CDMA800
Interfered
Systemf2f1
2f1-f2
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IM3 Products2f1-f2
DCS1800GSM900DCS1800TRUNK800
DCS1800CDMA800DCS1800TRUNK800
DCS1800WCDMAWCDMADCS1800
DCS1800GSM900DCS1800CDMA800
CDMA800WCDMAWCDMATRUNK800
CDMA800CDMA800TRUNK800TRUNK800
CDMA800GSM900GSM900TRUNK800
CDMA800DCS1800DCS1800TRUNK800
CDMA800WCDMAWCDMACDMA800
CDMA800DCS1800DCS1800CDMA800
TRUNK800WCDMAWCDMATRUNK800
TRUNK800DCS1800DCS1800TRUNK800
TRUNK800GSM900CDMA800TRUNK800
TRUNK800DCS1800DCS1800CDMA800
TRUNK800GSM900CDMA800CDMA800
Interfered
Systemf3f2f1
WCDMATRUNK800DCS1800GSM900
WCDMACDMA800DCS1800GSM900
WCDMAWCDMAWCDMADCS1800
WCDMADCS1800DCS1800DCS1800
GSM900WCDMAWCDMATRUNK800
GSM900TRUNK800CDMA800TRUNK800
GSM900DCS1800DCS1800TRUNK800
GSM900CDMA800GSM900TRUNK800
GSM900WCDMAWCDMAGSM900
GSM900DCS1800DCS1800GSM900
GSM900WCDMAWCDMACDMA800
GSM900TRUNK800CDMA800CDMA800
GSM900GSM900GSM900CDMA800
GSM900DCS1800DCS1800CDMA800
Interfered
Systemf3f2f1
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Combin
er
Input 1
Input 2
Output
Generating
IM products Power level of IM productsdepend on:
Power level of input signalsHigher input signalscause higher IM products
Minimum IM performance ofthe components
IM2 -140dBcIM3 -150dBc
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Interference Analysis Conclusion
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Isolation Needed to Restrain Spurious Emissions
Isolation Needed to Restrain IM
150dB Isolation is the safe guaranteeHigher BTS power cause higher power of IMproducts
30308690WCDMA
28288690DCS1800
28289090GSM900
28757590CDMA800
90757590Trunk800
WCDMADCS1800GSM900CDMA800Trunk800
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Propagation Loss
RX
TX
Air
Isolation
Lp is the propagation loss
Lp = 32.4 + 20log(d) + 20log(f)d is distance [km]
and fis the
frequency [MHz]
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If we assume a distance
of 1 m between RX/TX
antenna then we get the
following values for Lp.
Lp = 32.4 + 20log(d) + 20log(f)
800 MHz Lp = 30 dB
900 MHz Lp = 31 dB
1800 MHz Lp = 37 dB
2 GHz Lp = 38 dB
Propagation Loss
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Interference
BTS BTS BTS BTS BTS
POI
Tx
Spurious EmissionsIM Product
Must restrain interferences at POI
Provide enough isolation to
mitigate Spurious Emissions and IMproductIf the isolation not enough, extra airisolation is necessary
produceproduce
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Duplex Solution
Spurious Emissions IM Interferences
External filter needed toprovide extra isolation.Require very highperformance of filters.
The only way to avoidIM effect depends onthe high performanceof combiner, etc.
High cost of R&DExpensive materialsHigh requirement of manufacture
Excellent products performance
- Reduced Stability and Increase Risks
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Simplex Solution
Spurious Emissions IM Interferences
Air isolation is more than 30dB.More than 40dB transmission loss from
Tx to Rx.
In-building network is highly stable.Requirement of maintenance is low.