04 OWJ100103 WCDMA Base Station System Planning (With Comment) ISSUE 1

WCDMA Base Station System Planning www.huawei.com

Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

Objectives Upon completion of this course, you will be able to: Familiarize the principles for BS site selection Familiarize the principles for antenna selection and installation Know the causes of pilot pollution and the related solutions Know the notes for the co-existence of multiple systems


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Contents 1. Site Selection 2. Antenna Feeder System Design 3. Pilot Pollution 4. Multi-system Coexistence Planning


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Contents 1. Site Selection 1.1 Principles for Site Selection 1.2 Site Evaluation 1.3 Site Survey


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General Process for Site Selection Step 1: The network planning engineer generates a list of ideal sites Step 2: The survey engineer makes selection and survey according to the planned sites Step 3: For a complex area, make a propagation test to check whether the coverage is OK Step 4: After the site is selected, contact the owner or landowner to check whether the site can be purchased or leased


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Purpose of Site Selection Selecting a site that can cover the target area and has the lowest interference to others The selected site should be possibly closest to the traffic hotspot The antenna height depends on the type of the area where the site is located The key point is how to control the interference


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Principles for Site Selection The sites should be laid out according to the mesh, with the allowed deviation not larger than 1/4 of the BS radius The legacy sites are preferred if the BS layout is not affected The position of a new site should be a place with convenient traffic and power supply At the early stage of the network construction, the most important areas should be provided with good coverage


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Principles for Site Selection When the site is in a mountainous area, near lake, sea, or building with glass wall, the effect of signal reflection should be considered When the site is in urban, we can use the height difference of buildings to form network hierarchy


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Principles for Site Selection In general, a site should not be built on a high mountain beside a city or in a suburb The site should not be built beside a broadcasting station, radar station, or other interference source The site should be far away from a hurst in order to avoid fast fading of signal The coverage edge of the site should not be within the high traffic density area


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Site Selection in High-density Urban Area The antenna should be lower than the average height of buildings in the area The antenna should not be blocked by any nearby building The antenna should be installed at the edge of the building


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Site Selection in Urban Area The antenna should be slightly higher than the average building in the area Line-of-sight links may exist in the most portion of the area covered by the BS


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Site Selection in Suburb The antenna should be 5m–10m higher than the average building in the area Line-of-sight links should be available in the most portion of the area covered by the BS Only some line-of-sight links cross the cell border


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Site Selection in Rural Area or on Road The antenna should be 10m-20m higher than the average building in the area Good line-of-sight links are available in each direction

If the site is close to a town, the azimuth and tilt angle of the antenna should be adjusted for controlling the interference


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How to Evaluate a Candidate Site Transmission resources Wireless environment

Power supply

Planning result Engineering feasibility


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Wireless Environment The RF engineer should check the following on each candidate site and the nearby sites:

Does the candidate site well cover the target area?

Is there any RF interference on the candidate site?


Is there any apparent barrier found in the photos or the map?

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Transmission Resources The selection of a candidate site is often affected by the transmission planning: Is the optical fiber or E1 transmission available?


Is any line-ofsight link to the microwave node available?

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Engineering Feasibility The new site should facilitate the use of vehicle and lifting equipment

Requirements on the building A safe and convenient passage The moving of the equipment to the site room through a lift or a goods elevator in the building should be easy


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Power Supply Proper power supply should be available at the site The total power consumption of the main equipment and auxiliary equipment should be considered


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Meaning of Site Survey The results of the site survey may affect the quality and smooth construction of the whole project The reasonableness of the site is related to not only the coverage of the site but also the coverage of the peripheral sites Objectives: Providing a detailed construction scheme for the network deployment to guide equipment preparation, engineering construction, installation and commissioning


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Tasks of Site Survey The survey engineer makes a detailed survey according to the plan made at the site selection stage Survey items BS location Equipment room construction Antenna selection Equipment installation location

After completing the survey, the survey engineer submits a survey report Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

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Site Survey Flow Wireless network plan

Output Search Rings

Site list

2G site?

New site (prefix: NewSite)?

Site conditions determined?

Obtain candidate sites

Site survey

Site survey report

Noise test

Noise test report


Site requirement met?

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Preparation: gathering information Familiarize the project profile, and collect project data, including: Engineering document Local map BS survey table Contracted configuration list Contract feedback table Information about the legacy network


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Preparation: tools required Before the site survey, make sure that the following tools are available: GPS receiver Digital camera Compass Telescope Laser range finder Laptop Tape measure Map


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Detailed Survey Measuring the longitude, latitude, and height of the site Use the GPS receiver to measure the longitude and latitude of the site Use the laser range finder to measure the relative height and altitude of the site If no laser range finder is available, use a GPS receiver to measure the height through air pressure (the error depends on the weather), or estimate the height


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Detailed Survey Gathering information about the antenna installation platform Draw the schematic diagram of the antenna installation platform, and mark the installation location of all the equipment on the platform After the antenna installation location is determined, mark the related information (antenna installation location, installation mode, pole length, and so on) on the schematic diagram


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Detailed Survey Measuring the propagation environment Write down the height of the barrier in each direction and the distance between the barrier and the site Check whether some antennas of any other communication equipment exist nearby the site If any, write down the location (direction and distance), band, transmit power, height, azimuth, tilt angle of the antenna


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Summary This chapter covers the following: The process for site selection and principles for site selection The preparations and process for site survey


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Antenna Feeder System Jumper Grounding clip Feeder Grounding clip

Grounding clip Jumper


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TMA TMA (Tower Mounted Amplifier) is installed on a tower. It is close to the antenna. In general, the TMA and the antenna are connected through one 1/2“ jumper of 2m-3m long A TMA improves the sensitivity of the system and increases the upstream coverage of the system. It also lowers the transmit power of an MS, reduces the interference noise inside the system, and improves the call quality Triplex TMA Transmitter filter Note B

Bypass

TMA feed bias tee Receiver filter

LNA

Antenna

Receiver filter

DC


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Feeder Common feeder types: 1/2", 7/8", 5/4“

Principles for feeder selection If the feeder is longer than 50m, a 5/4“ feeder is required. If the feeder is shorter than 50m, a 7/8” feeder is required. A 1/2“ feeder is used as the jumper between the antenna and feeder or the one between the feeder and the BS top

Loss of 2GHz feeder Feeder type

Manufacturer

LDF5-50A (7/8")

ANDREW

6.46 dB

LDF6-50 (5/4")

ANDREW

4.77 dB

FSJ4-50B (1/2")


Loss (100m)

17.7 dB

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Classification of Antennas By radiation direction Directional antenna and omni-antenna

By appearance Plate antenna, mushroom antenna, whip antenna

By polarization mode Single polarization antenna and by-polarization antenna


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Antenna Type Selection Antenna type selection is important to the network quality According to the terrain or traffic distribution, the antenna environment falls into the following types: Urban area, suburb, rural area, road, indoor, and so on

Suburb

Urban area

Rural area

Road Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

Indoor

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Antenna Selection for Urban Area Directional antenna ±45º dual polarization Horizontal beam width: 65º Gain: 15 dBi Preset 6º electrical tilt or 0º– 0º adjustable electrical tilt + 0º–15º adjustable mechanical tilt Upper side-lobe suppression + null filling Front-to-back ratio:

25dB


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Antenna Selection for Rural Area Environment characteristics in rural area Sparse BS location Low traffic Wide coverage required

Directional antenna Vertical polarization Horizontal beam width: 90º Gain: 18 dBi No preset tilt

Omni-antenna Vertical polarization Gain: 11 dBi No preset tilt


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Antenna Selection for Suburb In selecting an antenna for a suburb, the suggestions on the antenna selection for urban area or rural area can be referenced An omni antenna is not recommended, in order to facilitate smooth upgrade in the future In a suburb, if the antenna uses a tilt angle, the tilt angle should be small


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Antenna Selection for Road Directional antenna Horizontal beam width: 30º; gain: 21 dBi Vertical polarization; no preset tilt

"8"-shaped antenna Bidirectional horizontal beam width: 70º; gain: 14 dBi Vertical polarization; no preset tilt

Heart-shaped antenna Horizontal beam width: 210º; gain: 12 dBi Vertical polarization; no preset tilt


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Selection of an Indoor Antenna Omni-antenna Vertical polarization; gain: 2 dBi Horizontal beam width: 360º; vertical beam width: 90º

Directional plate antenna Vertical polarization; gain: 7 dBi Horizontal beam width: 90º; vertical beam width: 60º

Log periodic antenna (a kind of wideband antenna) Vertical polarization; gain: 11.5 dBi Horizontal beam width: 55º; vertical beam width: 50º


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Principles for Antenna Height Design For a flat urban area, the effective height of an antenna is usually about 25m For a suburb or rural area, the height of the antenna can be about 40m A too high antenna may lower the coverage level beside the antenna (a blind zone under the tower), which is more severe for an omni-antenna A too high antenna may result in cross coverage, increase the interference, and affect the network performance


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Principles for Antenna Azimuth Design The central lobe of the antenna should face the hightraffic area to improve the signal strength and call quality For the urban area, the overlapping coverage ratio of the adjacent cells should not exceed 10% For the suburb or rural area, the separation angle between the antenna directions of the adjacent cells should be not lower than 90º For the high-density urban area, the central lobe of the antenna should not face a straight street


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Principles for Antenna Tilt Design The antenna tilt technology can effectively control the coverage and reduce the intra-system interference The antenna tilt angle should be determined according to the situation. It should reduce the interference between the cells with the same frequency and meet the coverage requirement In designing the antenna tilt angle, factors such as transmit power of BS, antenna height, cell coverage, and wireless propagation environment should be considered


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Implementation of Antenna Tilt The antenna tilt beam can employ the fixed electrical tilt, mechanical tilt, or both The fixed electrical tilt angle is related to the antenna type The mechanical tilt angle is adjustable and usually does not exceed 15º

Electrical tilt and mechanical tilt generate different surface radiation. If the tilt angle is small, the difference is not distinct. If the tilt angle is large, the difference is distinct

fixed electrical tilt Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

mechanical tilt Page44

Antenna Installation Environment The installation environment includes the ambient environment of the antenna and that of the BS For the ambient environment of the antenna, the antenna isolation and the effect of the tower and rooftop on the antenna should be considered For the ambient environment of the BS, the effect of the high buildings within the 500m on the wireless signal propagation should be considered

-60 relative to antenna azimuth

Antenna azimuth

-60 relative to antenna azimuth

Antenna azimuth

<=30 > 30 +60 relative to antenna azimuth

+60 Wall

Wall


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Antenna Installation Environment Note: An antenna should be kept away from barriers, otherwise, a large shadow area may appear For example, if the antenna is installed on a rooftop, it should be installed at the edge of the rooftop, otherwise the wireless signal may be blocked by the rooftop D

h

the distance between

the distance between

antenna and the edge of

the bottom of antenna

the building

and flat

0m~2m

0.5m

2m~10m

1m

more than 10m

2m


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Requirement on Installing Space Diversity In case of space diversity, the distance between two receive antennas should be 12 – 18 , (1 = 0.15m (2GHz)) The effect of the vertical diversity is the same as that of the horizontal diversity only when the vertical diversity distance is 5–6 times the horizontal diversity distance

Note:

space diversity distance(2--3m for wcdma) actual installed distance


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Summary This chapter covers the following: The principles for designing antenna height, tilt, azimuth in difference situation


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Concept of Pilot Pollution Concept of pilot pollution Pilot pollution means that there are too many strong pilots within the coverage, but none of the pilots is dominant

Criteria of pilot pollution There are more than 3 pilots with Ec > -95 dBm The level difference between the strongest pilot and the fourth strongest pilot is < 5 dB


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Effect of Pilot Pollution Pilot pollution is specific to the CDMA system CDMA and greatly affects the network performance Effect of pilot pollution High BLER Low system capacity High call drop rate due to frequent handover Low access success rate due to no dominant cell


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Detection of Pilot Pollution

Not Good

Good

Area with pilot pollution


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Pilot pollution

Causes of Pilot Pollution The causes of the pilot pollution includes: Unreasonable cell layout Too high site or antenna Unreasonable azimuth or tilt angle of an antenna Effect of the back lobe of an antenna Effect of the ambient environment of the coverage


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Unreasonable cell layout Site C

Site A Site B

The distances among the Site A, B and C are not balanced, and the location relation between the Sites is distinctly different from an equilateral triangle Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

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Too high site or antenna

Pilot pollution

The antennas of A and C are too high, so it is hard to control overshooting


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Unreasonable azimuth of an antenna

The antenna azimuth of the sector with scramble of 100 is unreasonable Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

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Unreasonable tilt angle of an antenna

The too small antenna tilt angle results in overshooting Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

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Effect of the back lobe of an antenna

Front-to-back ratio of the antenna does not meet the requirement, so the signal of the back lobe leaks Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

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The Ways to Reduce Pilot Pollution An area with pilot Pollution can be predicted in the planning simulation Optimize the planned scheme to avoid the pilot Pollution

Optimal solution – excellent system design Proper site Proper azimuth and tilt angle of antennas Proper transmit power and power ratio of sites


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Summary This chapter covers the following: Concept, criteria, causes, and the ways to reduce pilot pollution


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2G/3G Co-located Site Site room 3G Co-

Site

feeder

Cotransmission

2G

Power

Site Battery


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Air conditioner

2G/3G Co-located Site The GSM and CDMA site resources in the legacy system should be fully referenced and used in the 3G network Site co-location helps to reduce the number of sites and make full use of resources such as equipment, tower, and rooftop, thus reducing site cost and improving the deployment efficiency of 3G network Site co-location minimizes the inter-system interference and makes the interference controllable


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Contents 4. Multi-system Coexistence 4.1 Co-located Tower, Antenna Pole 4.2 Co-feeder 4.3 Others


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Co-located Tower, Antenna Pole If the WCDMA and GSM900/DCS1800 share the tower, antenna, or rooftop, the major problem lies in the inter-system interference Spurious radiation Inter-modulation Receiver block Other EMC problems


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Interference between WCDMA and others WCDMA

GSM (DCS) 1800

PDC (PHS)

TD-SCDMA

1920 ~ 1980 MHz 890 ~ 915 MHz

1710 ~ 1785 MHz

1900 MHz ~

1880~1920MHz,

Downlink 2110 ~ 2170 MHz 935 ~ 960 MHz

1805 ~ 1880 MHz

1915 MHz

2010~2025 MHz

TDD mode

TDD mode

Uplink

GSM 900

GSM 900

DCS1800 Tx

TD-SCDMA


PDC (PHS)

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WCDMA

Isolation requirement and solutions WCDMA

GSM 900

GSM (DCS) 1800

PDC (PHS)

TD-SCDMA

36dB

65dB

89dB

41dB

d>0.2m

d>2m


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Co-feeder Advantages of co-feeder The legacy feeder is used, simplified the construction and reduces the cost If the antenna isolation does not meet the requirement, cofeeder + multiplexer can be used

filter


duplexer

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Co-feeder Disadvantages of co-feeder The multiplexing filters of the new system are connected with those of the legacy system, which will affects the legacy network It is impossible to implement inter-system isolation through antenna isolation. If the requirement on the inter-system isolation is high, additional filters are needed between the multiplexing filter and the BS


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Co-feeder GSM

WCDMA

GSM WCDMA

TMA TMA

Duplex filter

Duplex filter Co-located feeder Co-located feeder Duplex filter

GSM

WCDMA

Isolation < 50dB Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

Duplex filter Filter (A)

GSM

WCDMA

Isolation >50dB Page71



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Co-transmission: Fractional ATM E1/SDH(Abis)

BTS

Nx64kbps NodeB

At the early stage of WCDMA construction, GSM provides E1/SDH transmission resources for the WCDMA


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Co-transmission: CES

BTS

E1 NodeB

E1/SDH(Iub)

At the mature stage of the WCDMA construction, the required capacity of the WCDMA system is high, and WCDMA can provide transmission channels for the GSM Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

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Co-located Auxiliary Equipment Equipment room The NodeB is configured with only one cabinet, so only a little space is required The NodeB is heavy, so the bearing capacity of the equipment room should be considered

Power supply system The 3G BS can use the legacy DC power and storage batteries in the equipment room

Grounding system The grounding requirement of the 3G BS is similar to that of the BS of any other wireless system Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

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Co-located Auxiliary Equipment Cable rack The legacy indoor and outdoor cable racks (troughs) are recommended. If necessary, cable racks (troughs) can be added

Air conditioner The NodeB causes much heat, so it is necessary to reconsider the capability of the air conditioners in case of co-located equipment room

Co-located feeder window In general, there are 12 holes in the feeder window in the equipment room. They can be shared by two sets of systems with general capacity configuration


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Summary This chapter covers the following: the notes for coexistence of multiple systems, including major interference, isolation requirement, co-located site, and so on


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Thank you www.huawei.com

04 OWJ100103 WCDMA Base Station System Planning (With Comment) ISSUE 1

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