owj101108 wcdma rnp antenna isolation analysis (umts-gsm) issue1.1

8/11/2019 Owj101108 Wcdma Rnp Antenna Isolation Analysis (Umts-gsm) Issue1.1

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Course OWJ101108

WCDMA RNP Antenna Isolation

Analysis (UMTS-GSM)

ISSUE 1.1


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OWJ101108 Antenna Isolation Analysis (UMTS-GSM) ISSUE1.1 Table of Contents

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Table of Contents

Course Description........................................................................................................................... 1 Course Introduction ..................................................................................................................... 1 Targets of the course .................................................................................................................. 1 References .................................................................................................................................. 1

Chapter 1 Scenario Classification .................................................................................................. 2 1.1 Co-Existence ......................................................................................................................... 2 1.2 Co-siting ................................................................................................................................ 3

Chapter 2 Interference Analysis...................................................................................................... 5 2.1 Assumption from GSM and 3GPP specifications.................................................................. 5

2.1.1 WCDMA BS ................................................................................................................ 5 2.1.2 GSM BS...................................................................................................................... 6

2.2 GSM to UMTS....................................................................................................................... 6 2.3 UMTS to GSM....................................................................................................................... 7

Chapter 3 Interference Test ............................................................................................................. 8 3.1 Interference test methods ..................................................................................................... 8

3.1.1 GSM Spurious Emission Test Configurations ............................................................ 8 3.1.2 Test Equipments and Accessories ............................................................................. 8 3.1.3 Test Process............................................................................................................... 9

3.2 Interference test results......................................................................................................... 9

Chapter 4 Antenna Isolation Test.................................................................................................. 10 4.1 Test method ........................................................................................................................ 10

4.1.1 Test condition ........................................................................................................... 10 4.1.2 Antenna Isolation Test Configurations ..................................................................... 11

4.1.3 Test Equipments and Accessories ........................................................................... 11 4.1.4 Test Process............................................................................................................. 11 4.2 Test results.......................................................................................................................... 12

4.2.1 Case 1 Antenna Isolation of GSM900 and UMTS................................................. 12 4.2.2 Case 2 Antenna Isolation of GSM1800 and UMTS............................................... 12

Wide-band Antenna Selection ....................................................................................................... 13


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OWJ101108 Antenna Isolation Analysis (UMTS-GSM) ISSUE1.1 Course Description

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Course Description

Course Introduction

Targets of the course

References


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OWJ101108 Antenna Isolation Analysis (UMTS-GSM) ISSUE1.1 Chapter 1 Scenario Classification

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Chapter 1 Scenario Classification

1.1 Co-Existence

Co-existence is that UMTS sites and GSM sites are in the same geographical area, butnot co-located.Figure 1-1 shows an example of co-existence.

Cell radius = 0.333 m

1000m

Figure 1-1 co-existence

In this scenario, antenna location of different system is random from each other. If theantennas of different system are shooting at each other, the victim cells will reduce a loton both capacity and coverage, or even is blocked if the interference is strong enough.Because of this, the radio network planner has to be careful on this scenario to avoidantennas point to each other.

Normally, the worst case for this is not macro cell to macro cell, but macro cell to microcell. This may introduce the dead zone for MS. Figure 1-2 gives an example of this

worst case:


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Figure 1-2 worst case for co-existence

Actually, if GSM user is at the cell edge of GSM macro cell meanwhile much close toanother UMTS micro cell, it will have great interference impact on UMTS network. Forexample, assuming GSM MSs RF performance is only satisfy GSM 05.05, thespurious emission to UMTS band is -30 dBm/3M (around -29dBm/3.84M ). If theMinimum Coupling Loss is 50dB, the interfering signals will around -79dBm/3.84M. Formore details of the interference calculation part, please refer to chapter 2.

The worst case can be avoid either we keep the sites co-located, or enlarge the MCL.

Co-existence currently is not a popular design in UAE because Etisalat is the onlymobile operator in UAE and has already a successful GSM operator. Co-siting forUMTS and GSM is more efficient way to building 3G network.

1.2 Co-siting

Co-siting is that both UMTS and GSM sites are co-located in the same place. Asmentioned above, Co-siting is more popular way to build UMTS network. Figure1-3shows an example of co-siting:


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Cell radius = 0.333 m

1000m

Figure 1-3 co-siting

Comparing with co-existence, co-siting has some advantages:

Operator can reuse the resources of old sites and reduce the cost for building UMTSnetwork;

Operator can reuse the GSM drive test and optimization results and take as a referenceto UMTS (for example: BCCH singal distribution);

Co-siting can reduce near-far effects, because pathloss to both UMTS and GSM arealways equal and dead zone are less likely.

Since co-siting is the most popular application in UAE. The following chapters are allfocus on this part.


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OWJ101108 Antenna Isolation Analysis (UMTS-GSM) ISSUE1.1 Chapter 2 Interference Analysis


Chapter 2 Interference Analysis

For co-siting scenario, the interference situation we have to investigate is:

GSM BS transmitting antenna is interfering UMTS BS receiving antenna;

UMTS BS transmitting antenna is interfering GSM BS receiving antenna;

In the following part, we will only investigate on these two situations.

2.1 Assumption from GSM and 3GPP specifications

2.1.1 WCDMA BS

1. Spurious emission

In 3GPP specification, scenario of co-existence with GSM has already beenconsidered and it has more rigid requirements to spurious emission on GSM 900 bandand 1800 band.Table 2-1 shows the results:

Table 2-1 Specification of UMTS spurious emission (from 3GPP 25.104)

Bands (MHz) Maximum Level/ Measurement Bandwid th

30 ~ 1000 876 ~ 915 MHz - 98 dBm/100 KHz921~960MHz -57dBm/100KHz

Others -36dBm/100KHz1000 ~ 2100 1710 ~ 1785 MHz - 98 dBm/100 KHz

1805~1880MHz -47dBm/100KHz1893.5~1919.6MHz -41dBm/300KHz1900~1920MHz -86dBm/MHz1920~1980MHz -96dBm/100KHz

2. BS acceptable noise calculation

Normally, background noise without loading is calculated with formula:BG_Noise=KTW+NF, where:

K: Boltzmann constant;

T: temperatures in degrees Kelvin;

W: receiver bandwidth;

NF: noise figure of BS;

The typical value for KT=-174dBm/Hz, and assume typical NF=3dB, so the typicalBG_Noise=-105dBm/3.84MHz.

A typical acceptable sensitivity degradation level of radio system is less than 0.4 dB. Itmeans that the interference is 10dB lower than the background noise as the noisefloor will rise 0.4dB after adding 10 dB low interference to the background noise.Based on the above BG_Noise value, the extra interference signal should be less than-115 dBm/3.84MHz.


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2.1.2 GSM BS

1. Spurious emission

In GSM 05.05 specification, the limitation for GSM 900 and DCS 1800 spuriousemission of UMTS band is very low, only 30dBm/3MHz:

Table 2-2 Specification of GSM900 and DCS1800 spurious emission (from GSM 05.05)

Band Maximum Level/ Measurement Bandwid th

9KHz 1GHz 36dBm/3MHz1 12.75GHz 30dBm/3MHz

2. BS acceptable noise calculation

Same as UMTS, background noise can also be calculated with formula:BG_Noise=KTW+NF

The typical value for KT=-174dBm/Hz, and typical NF=3dB, so the typicalBG_Noise=-118dBm/200kHz.

A typical acceptable sensitivity degradation level of radio system is less than 0.4 dB. Itmeans that the interference is 10dB lower than the background noise as the noise floorwill rise 0.4dB after adding 10 dB low interference to the background noise.Based onthe above BG_Noise value, the extra interference signal should be less than -128dBm/200kHz.

2.2 GSM to UMTS

For UMTS, NodeB acceptable noise is less than -115 dBm/3.84MHz. According to table2, the worst case of GSM spurious emission leaked in UMTS band is -30dBm/3MHz(-29dBm/3.84MHz). Thus the isolation between GSM transmitting antenna and UMTSreceiving antenna is: -29dBm (-115dBm) = 86dB. Assume both antennas aredirectional antenna and have same azimuth (see Figure 2-1).

Figure 2-1 Co-located scenario: space isolation distance (horizontal/vertical)


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In this scenario, the horizontal distance needed between two antennas is so large that itis impossible to be satisfied when co-siting. This is the worst case and additionalrejection filter should be used at the GSM BS side if this case happens.

Actually, the RF performance of GSM BS equipment is vendor dependent and normally

is much better than that from GSM specification. For example, normally for GSM 900BTS, in order to co-located with DCS 1800, extra attenuation will achieved in DCS 1800band, which is close to UMTS band.

2.3 UMTS to GSM

For GSM, BTS acceptable noise is less than -128dBm/200KHz. According to table 1,the maximum GSM spurious emission leaked in 900 and 1800 band is -98dBm/100KHz(-95dBm/200kHz). Thus the isolation between UMTS transmitting antenna and GSMreceiving antenna is: -95dBm (-128dBm) = 33dB. Assume both antennas aredirectional antenna and have same azimuth (see figure 4). In this scenario, theaverage space distance between two antennas is less than 1m for horizontal, and lessthan 0.2m for vertical based on the test data in Table 4-4 and 4-5. This is a reasonableisolation to achieve under mono pole or building roof situation.

Comparing the results above, the isolation got from GSM interfering UMTS is therestricted part.


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OWJ101108 Antenna Isolation Analysis (UMTS-GSM) ISSUE1.1 Chapter 3 Interference Test


Chapter 3 Interference Test

3.1 Interference test methods

From the theoretical calculation of chapter 2, we find that the isolation is very difficult toachieve when two systems co-located. This result is too pessimistic. Actually, the RFperformance of BS equipment is vendor dependent and normally is much better thanthat from UMTS and GSM specification.

Interference test is the best way to get the idea of how many isolation two systems isactually needed. The test method is as following:

3.1.1 GSM Spurious Emission Test Configurations

Figure 3-1 GSM Spurious Emission Test Configuration

3.1.2 Test Equipments and Accessories

The test equipments and accessories are listed in Table 3-1

Table 3-1 List of test equipments and accessories

test equipments and accessories Type Number Mount

Spectrum Analyzer Agilent E4445A with LNA option 1WCDMA BPF(Band Pass Filter) LGP145 1WCDMA/GSM900 Diplexer LGP135 or Kathrein 782 10250 1WCDMA/GSM1800 Diplexer LGP145 or Kathrein 782 10243 1

Dummy Load RF power handling >100W 1


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OWJ101108 Antenna Isolation Analysis (UMTS-GSM) ISSUE1.1 Chapter 3 Interference Test


test equipments and accessories Type Number Mount

Test Cable 4Connecter Adaptor DIN(male)/N(female) 6

3.1.3 Test Process

The test process is listed in Table 3-2:

Table 3-2 List of test process

E4445A Settings

Frequency band 1920~1980MHzRBW 100KHzVBW 300KHz

Average ON Average times: 20LNA Status: ONSteps1) Set up the test system according to figure 3-12) Let GSM BTS output maximum power3) Record the spurious power using Peak-Search function

3.2 Interference test results

Void.


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OWJ101108 Antenna Isolation Analysis (UMTS-GSM) ISSUE1.1 Chapter 4 Antenna Isolation Test


Chapter 4 Antenna Isolation Test

The exact antenna isolation of two systems needs to be less sensitivity degradationbased on the analysis in chapter 2 and 3. In practice, it is difficult for engineer toachieve a real space isolation distance between UMTS and GSM antennas. Thereason is that the two antennas are working in a merged near-field zone of RFelectromagnetic field, which the electromagnetic field distribution and isolation levelneeds more complex analysis theoretically. A field test of antenna space isolation isadapted to fit the current situation in UAE project. The related test is described in thischapter.

4.1 Test method

The test is carried out by two cases which are GSM900-UMTS antenna andDCS1800-UMTS antenna. Each antenna is cross polarization type. The configurationof test system is shown as figure 4-1.

4.1.1 Test condition

Two cases are tested:

GSM 900MHz cross-polarization antenna and UMTS cross-polarization antenna

DCS 1800MHz cross-polarization antenna and UMTS cross-polarization antenna

The features of antennas tested are as following:

Table 4-1 Features of Antenna tested

Vendor Type Number Gain HBW VBW

GSM 900 Antenna JB 7600 17dBi 60 9

DCS 1800 Antenna JB 5022004 18dBi 60 5.5

UMTS Antenna MAT 5162100 18.5dBi 65 6

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

GSM 900 band and 2dB in GSM1800 and UMTS bands. The isolation data in this test isprocessed so that the cable loss is excluded.

The antenna ports are selected so that transmit antenna and receive antenna have thesame polarization.

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


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4.1.2 Antenna Isolation Test Configurations

Figure 4-1 Configuration Diagram of Antenna Isolation Test

4.1.3 Test Equipments and Accessories

The test equipments and accessories are listed in Table 4-2:Table 4-2 List of test equipments and accessories

Test equipments and accessories Type Number Amount

Spectrum Analyzer HP8594E 1Test Cable 9m 2

Antenna GSM,WCDMA antenna 2Connecter Adaptor DIN(male)/N(female) 4Matching Load N(male) 2

4.1.4 Test Process

The brief description of three test steps and instrument settings are given in Table 4-3.

Table 4-3 List of test equipments and accessories

HP8594E settings:Frequency band 890~2170MHzRBW 100KHzVBW 300KHz

Average ON Average times: 20output power:10dBmsignal type:CW

Steps1) Set up the test system according to figure 4-1


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2) Turn on RF power3) Record the isolation values at different frequencies.

4.2 Test results

4.2.1 Case 1 Antenna Isolation of GSM900 and UMTS

The antenna isolation data of GSM900 and UMTS antenna in two frequency bands isrecorded in Table 4-4. The cable loss is not included in these data.

Table 4-4 Antenna isolation data between GSM900 and UMTS

890MHz

902.5MHz

915MHz

935MHz

947.5MHz

960MHz

1920MHz

1950MHz

1980MHz

2110MHz

2140MHz

2170MHz

0.5m 65dB 68dB 68dB 71dB 65dB 70dB 55dB 58dB 62dB 49dB 52dB 62dB




4.2.2 Case 2 Antenna Isolation of GSM1800 and UMTS

The antenna isolation data of GSM1800 and UMTS antenna in two frequency bands isrecorded in Table 4-5. The RF loss of cables is not included in these data.

Table 4-5 Antenna isolation data between GSM1800 and UMTS

1710MHz

1747.5MHz

1785MHz

1805MHz

1842.5MHz

1880MHz

1920MHz

1950MHz

1980MHz

2110MHz

2140MHz

2170MHz






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OWJ101108 Antenna Isolation Analysis (UMTS-GSM) ISSUE1.1 Wide-band Antenna Selection


Wide-band Antenna Selection

For the antenna selection, introduce the new antenna is preferable, especially foroptimization freedom. But sometimes the room is limited and we have to use wide bandantenna for both GSM and UMTS.

When selecting wide band antennas for new UMTS system, it is better firstly followingchapter 2 and 3 to test the interference between each other and find the safe isolationvalue. Then with this isolation value, you can choose the proper wide-band antennafrom antenna list.

owj101108 wcdma rnp antenna isolation analysis (umts-gsm) issue1.1

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