c18 wcdma rnp antenna isolation analysis (umts-gsm)

8/10/2019 C18 WCDMA RNP Antenna Isolation Analysis (UMTS-GSM)

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Antenna Isolation Analysis (UMTS-GSM)


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Course Contents

Scenario Classification

Interference Analysis

Interference Test

Antenna Isolation Test


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Disadvantage of Co-Existence

Antenna may shooting at each other, the victimcells will reduce a lot on both capacity and coverage,

or even is blocked if the interference is strong

enough.

Worst case: macro -> micro, dead zone happens


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Co-Siting

Definition: Co-siting is that both UMTS and GSM

sites are co-located in the same place.

For 2G mobile network operator, Co-siting is the

most popular way to build UMTS network.

Cell radius = 0.333 m

1000m


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Advantage of Co-Siting

Operator may reuse the resources of old sites and

reduce the cost for building UMTS network;

Operator can reuse the GSM drive test (DT), consult

the previous optimization results and take as areference to UMTS (for example: BCCH signal

distribution);

Co-siting can reduce near-far effect, because path

loss to both UMTS and GSM are always equal and

dead zone are less likely.


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Course Contents



Interference Test



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Frequency Allocation for UMTS

1800 1900 2000 2100 2200 MHz


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3GPP and GSM Specification

WCDMA Base Station (BS )

Spurious Emission (SE):

Band Max Level/ Measurement Bandwidth (BW)

30~1000MHz 876~915MHz-98dBm/100KHz

921~960MHz-57dBm/100KHz

Others -36dBm/100KHz

1000~2100MHz 1710~1785MHz-98dBm/100KHz

1805~1880MHz-47dBm/100KHz

1893.5~1919.6MHz-41dBm/300KHz

1900~1920MHz-86dBm/MHz

1920~1980MHz-96dBm/100KHz


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BS accepted noise calculation:

BG_Noise = KTW + NF,

K: Boltzmann constant; T: temperatures in degrees, Kelvin;

W: receiver BW; NF: 3 dB;

KT= -174dBm/Hz, BG_Noise= -105dBm/3.84MHz

A typical accepted sensitivity degradation level of radiosystem is less than 0.4 dB. Based on the above BG_Noise

value, the extra interference signal should be less than -115

dBm/3.84MHz.

WCDMA BS Accepted Noise


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GSM BS

SE:

In GSM 05.05 specification, the limitation for GSM900 and

DCS1800 SE of UMTS band is very low, only 30dBm/3MHz

Bands Maxi Level/ Measurement BW

9KHz1GHz 36dBm/3MHz

112.75GHz 30dBm/3MHz

3GPP and GSM Specification


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BS allowed noise calculation:

BG_Noise= KTW + NF

K: Boltzmann constant, KT=174dBm/Hz;

T: temperature in degrees Kelvin;

W: receiver BW;

NF: noise figure of BS, 3 dB;

BG_Noise=118dBm/200kHz.

A typical allowed sensitivity degradation level of radio

system: < 0.4 dB. From above BG_Noise value, extra

interference signal should be:


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Interference Investigation for Co-siting

For co-siting scenario, the interference situation needs to

be investigated based on the Tx/Rx antenna scenario.

GSM Tx interferences UMTS Rx

UMTS Tx interferences GSM Rx


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Interference: GSM to UMTS

Case of directional antenna

NodeB accepted noise: 100m (H), and > 4m (H), not practical

Note: H - horizontal

Actually, RF performance of GSM equipment is vendors

dependent and normally is much better than that from GSM

specification. For example, normally for GSM900 BTS, in order to

co-located with DCS1800, extra attenuation will be achieved in

DCS1800 band, close to UMTS band.

Huawei DCS1800 BTS, SE in UMTS band:


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Interference: UMTS to GSM

For GSM, BTS accepted noise is less than -128 dBm.The max GSM SE leaked in 900 and 1800 band is

- 98dBm/100KHz (- 95dBm/200KHz). Thus the isolation

between UMTS Tx and GSM Rx antenna is:

- 95dBm( - 128dBm) = 33dB.

In this scenario, the average space distance between

two antennas is less than 1m for horizontal, and less

than 0.2m for vertical.


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Course Contents



Interference Test



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Interference Test

The isolation is relatively hard to achieve when twosystem co-located from theoretical calculation. This

result is too pessimistic.

In practice, RF performance of BS equipment is

vendors dependent and normally is much better than

that from UMTS and GSM specification.

Interference test helps in evaluating the antenna

isolation among different wireless systems.


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GSM Spurious Emission Test

WCDMAGSM

GSM BTS

GSM and

WCDMA

Diplexer

WCDMA

BPF

Antenna or

Dummy

Load

Spectrum

Analyzer

Agilent

E4445


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Test Equipments and Accessories

Items Note Amount

Spectrum Analyzer Agilent E4445Awith LNA

option

1

WCDMA BPF LGP145 1

WCDMA/GSM900

Diplexer

LGP135 or Kathrein 782

10250

1

WCDMA/DCS1800

Diplexer

LGP145 or Kathrein 782

10243

1

Dummy Load RF power >100W 1RF Cable 4

Adaptor DIN (male)/N (female) 6


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Test Process

Agilent E4445A Settings:

Frequency band

1920 ~1980 MHz

RBW

100KHz

VBW

300KHz

Average

OnAverage times: 20

LNA Status: On

Steps

1) Set up the test system

2) Adjust GSM BTS output power to max value

3) Record the spurious power value using Peak-Search

function


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Course Contents



Interference Test



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Test Condition

Testing under two cases with cross polarization (CXP)

antennas:

Case 1: UMTS and GSM900 , Case 2: UMTS and DCS1800

Two 9m 1/2 cables are used in this test and each cables loss is

regarded as 1dB in GSM900 band and 2dB in DCS1800 and UMTS bands.

The isolation data in this test is processed so that the cable loss isexcluded.

The antenna ports are selected so that Tx and Rx antenna have the same

polarization.

The antennas are installed 8m above ground and are directed toward the

same direction.

Bands Vendor Type Gain HBW VBW

GSM900 JB 7600 17dBi 60 9

DCS1800 JB 5022004 18dBi 60 5.5

UMTS MAT 5162100


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Test Configurations

Spectrum

Analyzer

HP8594E

UMTS

Antenna

GSM

Antenna


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Test Equipments and Accessories

Items Note Amount

Spectrum Analyzer Agilent E4445A 1

Signal Generator Max output power

>10dBm

Frequency band:

900 KHz ~ 2 GHz

CW output

1

Test Cable 3m 2

Antennas GSM, UMTS 2

Adaptor DIN (male)/N( female) 4

Matching Load N (male) 2


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Test Process

Agilent E4445A settings:

Frequency band

19201980 MHz

RBW

100 KHz

VBW

300 KHz

Average

On

Average times: 20 (mS)Signal generator settings:

Frequency: 1950 MHz

RF power: 10 dBm

Mode: CW

Steps

1) Set up the test system according to figure 1

2) Turn on RF power of signal generator

3) Record the power value of E4445A at 1950MHz


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Test Result

Case 1 Antenna Isolation of UMTS and GSM900

890

MHz

902.5

MHz

915

MHz

935

MHz

947.5

MHz

960

MHz

1920

MHz

1950

MHz

1980

MHz

2110

MHz

2140

MHz

2170

MHz

0.

5

m

65d

B68dB

68d

B

71d

B65dB

70d

B55dB 58dB 62dB 49dB 52dB 62dB

1.

0

m

70d

B72dB

73d

B

71d

B71dB

71d


1.

5

m

72d

B71dB

70d

B

69d

B72dB

72d


2.

0

m

71d

B73dB

73d

B

69d

B71dB

73d



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Test Result

Case 2 Antenna Isolation of UMTS and DCS1800

1710

MHz

1747.

5MHz

1785

MHz

1805

MHz

1842.

5MHz

1880

MHz

1920

MHz

1950

MHz

1980

MHz

2110

MHz

2140

MHz

2170M

Hz

0.

5

m

63dB 61dB 56dB 62dB 68dB 62dB 51dB 58dB 60dB 66dB 57dB 57dB

1.

0

m


1.

5

m


2.

0

m



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c18 wcdma rnp antenna isolation analysis (umts-gsm)

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