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Overview of 3G2G Co-site

Interference Analysis of 3G2G Co-site

Solution to 3G2G Co-site

Application Examples of 3G2G Co-site

Agenda

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Reduce the construction cost and rental cost of sites and save the construction cost and rental cost of antenna feeders.

Speed the construction of the 3G engineering and put 3G into operation quickly, seizing more market opportunities.

Avoid the negotiations with building managers during the course to obtain base stations and much unnecessary work.

Purpose of Shared Site Addresses

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The problems includes:The problems includes:q How to resolve the problem about 3G2G

interferenceq How to resolve the problem about

shared equipment roomsq How to resolve the problem about

transmission sharing q How to resolve the problem about

insufficient sitesq How to

Problems about Co-sites

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Equipment room

3G base station

Shared feeder

Shared transmission

Storage battery

Power

supply

Air-conditioner

2G base station

Illustration for 3G2G Co-site

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In the early stage, the GSM/DCS system provides transmission channels for WCDMA.In the later stage, the WCDMA system provides transmission channels for GSM/DCS.

Shared transmission equipment

Consider the condition about the area, load-bearing capacity and power supply of the equipment room when performing the installation.

Shared equipment rooms (including the power supply system and air-conditioner)

Shared antenna feeders --- separated with wave filteredShared feeders

Shared towers --- separately installed vertically or horizontallyShared support poles --- separately installed verticallyShared antenna planes --- separately installed horizontally

Shared installation positions

Contents Involved by Shared Station Addresses and Features

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Agenda

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Filter ReceiverTransmitter Filter

The interference between systems comes from the

transmitter.

The interference between systems is reflected by the effect on the receiver of the

base station.

The interference problem is the core problem about 3G2G co-site.

Interference Principle

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The interference of the receiver includes the spurious radiation interference coming from the transmitter, the block interference caused by the signals of the transmitter and the inter-modulation interference generated by the receiver itself.

Spurious radiation

Transmitter ReceiverInter-modulation

Transmission source

Interference Categories

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It refers to the signals transmitted by the transmitter that are beyond the frequency range specified by the carrier. These signals include harmonic wave components, parasitical radiation, cross-modulation products and inter-modulation products.

Transmission signals

Spurious signals

Spurious Radiation

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1873MHz1824MHz1824MHz1873MHz 1922MHz

LNA

Inter-modulation

product

Receiver inter-modulation occurs internally in the receiver. There are the following methods to avoid it: Add a suppression filter at the input terminal of the receiver. Adjust the position of antennas to improve the antenna isolation between the interfering system and the interfered system. Improve the linearity of the receiver.

Inter-modulation

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The receiver usually works in the linear area. When a strong interference signal comes to the receiver, the receiver works in the non-linear state and the signal even causes the saturation of the receiver in the serious condition. This phenomenon is referred to as block. It reflects that the receiver still has the capacity to normally receive and demodulate an expected signal in the condition where there is an interference signal.

RX TX

System A

RX TX

System B

BPF

LNA

BPF

LNAPA

PABPF

Block

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Signal

Noise

Spurious interference, inter-modulation interference and block interference cause the following problems: background noise rise, SNR value decrease and signal demodulation deterioration. Thus, error rate requirements cannot be met.

In the normal condition, if SNR>-19.4dB, the system can normally demodulate a voice at 12.2kbps.

Background Noise Rise

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DCS1800 Rx DCS1800 TX WCDMA Rx WCDMA TX

1710Mhz 1785Mhz 1805Mhz 1880Mhz 19200Mhz 1980Mhz 2110Mhz 2170Mhz

GSM900 Rx GSM900 TX WCDMA Rx WCDMA TX

890Mhz 915Mhz 935Mhz 960Mhz 19200Mhz 1980Mhz 2110Mhz 2170Mhz

The interference to 2G has been taken into account in the 3G protocol. Therefore, 3G has a very little interference effect on 2G and the effect can be ignored.

Schematic Drawing of Interference

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2G 3G

Space isolation

Filter isolation

Frequency optimization

Some Methods for Interference Isolation

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24272427Inter-modulation isolation

GSM900 to WCDMA

WCDMA to GSM900

DCS1800 to WCDMA

WCDMA to DCS1800 Requirement item

-30

39

1212-22In-band block isolation

92 92 38Spurious isolation

Typical isolation numerical value (dB)

The suppression effect of the transmitter and the receiver on interference is better than that indicated by the indices in the protocol. Moreover, in a practical environment, the isolation between the 3G and 2G is low. Therefore, it is veryeasy to meet the requirements of a project.

Requirements for the Isolation of Protocol

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Interference Analysis of WCDMA to GSM BS Node B based on test result :

26dBIsolation for 2G/3G Co- siting

10dBIsolation Margin

-134dBm/100KHzMax Interference in WCDMA RX Band

-107dBm/100KHzBTS IM

-119dBm/100KHzMax BTS Spurious in WCDMA RX Band

83dB@1920MHzStandard TX Filter Rejection

-51dBm/100KHzMax PA Spurious in WCDMA RX Band

3900 SeriesGSM BTS Type

In fact most GSM BTS index is better than the protocol, so 30dB isolation degree is enough according to actual network experience .

It is better than protocol actually

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Agenda

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Shared towers

Antennas are installed at the top of towers or on the raised floors of buildings. In most conditions, antennas can share towers or raised floors without added corresponding facilities.

Shared antenna planes

Antenna planes are the installation planes of antennas. In most conditions, antenna planes can be shared. However, we should check whether the space between antennas meets the requirement of isolation.

Shared support poles

If the lengths of support poles are long enough, antennas can share them. However, we should assure that the vertical isolation requirement between two systems can be met. In most conditions, it is required to add new support poles.

Shared Conditions

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Horizontal Space/Vertical Space definition

Horizontal Space installation Vertical Space installation

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1920 1980

UMTS2100 DLUMT2100 UL

2110 2170

60MHz 60MHz

960880 915

UMTS90 UL UMTS DL

35MHz

925

35MHz

0.5Minimum Horizontal distance (m)

0.2Minimum Vertical Distance at the same pole (m)

35Isolation DegreedB

Interference analysis result according to 3GPP 0505.V8.17.0

GSM900&UMTS2100 Interference Solution

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1920 1980

DCS1800 DLDCS1800 UL

2110 2170

60MHz 60MHz

18801710 1785

UMTS90 UL UMTS DL

75MHz

1805

75MHz

0.5Minimum horizontal distance (m)

0.2Minimum vertical distance at the same pole (m)

43Isolation degreedB

Interference analysis result according to 3GPP 0505.V8.17.0

DCS1800&UMTS2100 Interference Solution

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Agenda

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Installed on the tower, separated horizontally

Installed on the tower, separated vertically

Mauritius project: sharing the tower of 2G and separated by using antenna direction angles and height differences

Shared Tower Example

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Installed on the top of building, separated vertically

Installed on the top of building, separated horizontally

Hong Kong project: sharing the installation antenna plane of 2G and separated through the horizontal or vertical distance between antennas

Shared Antenna Plane Example

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3G NodeB2G base station

Hong Kong project application, sharing the installation platform of 2G

Shared Outdoor Installation PlatformShared Outdoor Installation Platform

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In Netherlands, Huawei distributed BBU (baseband processing unit) is placed in the outdoor type BTS cabinets of other GSM manufacturers.

Huawei BBU

Combiner(sharing antennas)

Shared Cabinet Example of BBU and GSM

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Share antenna or not?

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Separated antenna system is recommended if the installation space is enough

Recommendation solution(1)

GSM900+UMTS2100 GSM900+DCS1800+ UMTS2100

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Co-antenna system is recommended if the installation space is not enough

Recommendation solution(2)

GSM900+UMTS2100 GSM900+DCS1800+ UMTS2100

OR

GSM BTS

UMTS BBU

UMTS BBU

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Advantages

Disadvantages

Reduce the cost of antenna feeders and make the construction of engineering easier.

Save installation positions by sharing antenna feeders.

Avoid vision pollution and public worries of electromagnetic radiation.

The down tilt angles of shared antennas cannot be adjusted flexibly and the coverage directions are relatively fixed. (If we use theantennas of two systems, the down tilt angles of antennas are adjustable, but the cost is too high.)

For shared antennas, isolation can only implemented by the isolation designed for them. This isolation is usually only 30dB or so. We need add filters to implement the required isolation between systems.

Share antenna or not?

Thank youwww.huawei.com

wcdma 3g2g co-site solution

Documents

3g2g cositepage

interference problem

huawei technologies

3g2g interferenceq

interference principlepage

block interference

intermodulation interference

transmission channels