Interference Analysis (KO)

8/4/2019 Interference Analysis (KO)

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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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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.

Documents

Interference Analysis (KO)