HUAWEITECHNOLOGIES CO., LTD. Page 2HUAWEIConfidential
Foreword
The survey and layout of BTS is the basis of
construction for radio mobile network. It has the following
functions:
Showing the system design of the network planning
Determining the structure of future network
Determining the quality of network operation
Thus, the proper survey and layout of BTS can ensure
the installation, maintenance, and network planning.

Purpose
•Service flow of BTS survey
•Selection of site address
•Design of antenna
After learning this course, you should be
familiar with:

Contents
 Chapter 1 Service Description
 Chapter 2 Preparation
 Chapter 3 Site Selection
 Chapter 4 Antenna Design
 Chapter 5 Survey Document

Service Description
 Survey task
 Optical test
− Surrounding architecture environment and
nature environment
 Spectrum measurement
− Electromagnetic environment
 Site check
− Installation condition of antenna and
equipment
− Power supply and transmission supply
Survey purpose
Collect the site information required by the networking planning and
environment description. Check whether the site meets the requirements of
construction.

Service Description
 According to width of band, determine frequency multiplex mode
 According to capacity forecast, traffic distribution, and coverage
requirement, estimate the required quantity of BTSs.
 Confirm the position of BTS in theory.
 Perform BTS survey
 Design parameters of cell
 Network hierarchy structure, transmit power, antenna system,
including the type, height, direction, and down tilt of antenna
Position of BTS survey in the network planning

Radio network
estimation
report
Site
information
Whether
there is a site
Obtaining
spare sites
Site survey
Whether
conforming site
condition
Survey
report
Whether meeting
requirements of
site
Obtaining site;
selecting radius
Electromagnetic
environment
test
Yes
No
Yes
No
Yes
No
Service Flow

Contents

 Be familiar with the engineering and collect the materials that is
related to the project :
 Engineering document
 Background material
 Network status
 Map
 Configuration list
Preparation

 Prepare the following tools that are
available:
 Digital camera
 GPS satellite receiver
 Compass
 Ruler
 Laptop
Preparation

Preparation
 Survey preparation coordination meeting
Before survey, call in all the relative personnel to hold the survey
preparation coordination meeting. The main contents of this meeting are
listed as follows:
 Testing electromagnetic background
 Arranging survey and coordination personnel
 Preparing vehicle and equipment
 Making survey plan and confirming survey route
 Offering the primary schemes of transmission
and power

Contents

Site Selection
 After completing preparation and knowing about the coverage
requirements, start to select site.
When confirming the site, consider the following information:
 Original network condition
 Population distribution and local custom
 City structure and town distribution
 Main streets and traffic flow
 Mountainous region, lake, river, and coastline
 Long-term development trend

Principles of Selecting Site
Choosing sites in the
heavy-traffic region and
concentrated subscriber
region
Population distribution
Traffic distribution
Subscriber flow direction
 Principle
Surrounding environment
Signal propagation quality
Trying not to choose sites near
mountain, radar, broadcasting
station, forest, and electrical
factory

 The specific principles are described as follows:
 Construct BTS on the ideal position of a cell. The offset
should not exceed the ¼ of coverage radius.
 Under the condition of the BTS layout is not affected,
choose the existing equipment to reduce the construction
cost and period as possible .
 To control the coverage range, reduce the difficulty of
engineering construction, and be convenient for
maintenance, do not choose the sites on the mountain that
is on the border of the city or suburb.
(the relative altitude to the city: beyond 100m ～ 300m)
Principles of Selecting Site

Principles of Selecting Sites
 Construct the BTS at a place where transport is fluent, supply of
mains is available, environment is safe, and there is a few filed.
 Do not construct the BTS near the high-power radio transmit
station, radar station, and other interference sources.
 Construct BTS at a place that is far away from the forest to avoid
the fast fading of received signal.
 Consider the signal reflection and time dispersion when
constructing the sites in the mountainous area, precipitous shore,
dense lake area, highland city, and the environment with high
metal building.
 When choosing site in the complex, realize the division of network
structure according to the height of building.
 At the early stage of constructing network, because of a few of
BTSs, ensure good coverage in important areas.

Contents

 Selecting Antenna
Selecting Antenna
 The selection for antenna is an important part of determining
the network quality.
 According to the requirements of coverage and service
quality, traffic distribution, landform, coverage in the entire
network, and interference, to select the antenna.
 According to landform or traffic distribution, the environment
of using antenna can be categorized into:
 City, suburb, countryside, highway, mountainous area,
offing, tunnel, and indoor environment

Principles of Selecting Antenna
 Selecting Antenna for the BTS in the city
 Choose the directional antenna with 60° ～ 65° half power angle.
 Choose the antenna with about 15dBi gain.
 Choose the antenna with 3° ～ 6°tilt angle.
 Choose dual polarization antenna.

 Selecting antenna for the BTS in the suburb
 According to actual conditions, choose the directional antenna
with 65°or 90° half power angle.
 Choose 15 ～ 18dBi middling or high gain antenna.
 According to actual conditions, determine whether the tilt angle
should be used.
 Dual polarization antenna and vertical polarization antenna are
both available.

 Selecting antenna for the BTS in the countryside
 According to actual conditions, choose 90°or 120° directional
antenna or omni-directional antenna.
 Choose directional antenna with 16 ～ 18dBi gain.
 Do not choose presetting tilt antenna. Choose null filling antenna
for the high BTS.
 The vertical polarization antenna is recommended.

Selecting antenna for the BTS on the
highway
In general, choose narrow-beam and
high-gain directional antenna. According
to actual conditions, you also can choose
8-shaped antenna or omni-directional
antenna.
Because the BTS on the highway must
cover a long distance, do not choose the
presetting tilt antenna.
The vertical polarization antenna is
recommended.
The front-to-back ratio of the directional
antenna should not too great.

 Selecting antenna for the BTS in the tunnel
 Tunnel shorter than 2 km
Install the 10dB-12dB Yagi antenna/log-periodic
antenna/flat antenna in the jaws of tunnel to cover
a road that is less than 2km.
 Tunnel longer than 2 km
Use leaky feeder, coaxial cable, and fiber
distribution system.

 Selecting Indoor Antenna
 Omni-directional antenna
Vertical polarization, 2dBi gain, cap-shaped or cup-shaped, small
size, convenient for installation, graceful
 Directional antenna
Vertical polarization, 90°half power angle
7dBi gain

AntennaHeight
 Due to the installation space or cell planning, the heights of
antennas that are in different cells of a BTS can be different.
 For the BTS in the city, the height of antenna is about 25m.
 For the BTS in the suburb, the height of antenna is about 40m.
 If an antenna, particularly the omni-directional antenna, is too high,
the coverage level of the place that nears to the antenna may be
lowered, that is, no signal under the power.
 In addition, the too high antenna may lead to cross coverage and
intra-frequency/neighboring-frequency interferences that affect the
network quality.
 Principles of Design for Antenna Height

 Principles of Design for Antenna Azimuth Angle
Azimuth Angle
 Based on signal coverage, ensure that the azimuth angles of three sectors are the
same. Adjust the azimuth angles of antennas according to important coverage
objects on the border of city and suburb, in the traffic artery and isolated site of
suburb.
 To enhance the signal strength and improve call quality, adjust the major lobe of
antenna to face to the heavy-traffic areas.
 To control interference, adjust the major lobe of antenna to be apart from intra-
frequency cells.
 The cross coverage areas of neighboring cells in the city should not exceed 10%.
 The cross coverage areas of neighboring cells in the suburb and village should be
not too large. The azimuth angle of neighboring cells should not less than 90°.
 To avoid cross coverage, do not make the major lobe of antenna face to the
straight streets in the crowded areas.

 Principles of Design for Tilt Angle
Tilt Angle
 The beam tilt is a basic technology for improving Frequency Reuse
capability.
 The antenna tilt technology is used to control coverage scope and
reduce the interferences in the system.
 To reduce the interferences from co-channel cells and meet the
coverage requirements, set the tilt angles based on specific conditions.
 The design for tilt angle should be based on transmitter power, antenna
height, cell coverage, and radio environment.

Tilt Angle
 The antenna tilt is categorized into electrical mode and mechanical mode.
The angle of the electrical tilt is relative to the model of antenna. The angle
of the mechanical tilt is adjustable, but it is limited by installation accessory
and signal transportation. Often the angle should not exceed 15°.
 The electrical tilt and mechanical tilt have surface radiations that differ with
the increases of angles.

Installing Antenna
 A. Installation Environment
 The installation environment contains the ambient of antenna
and that of BTS.
For the ambient of antenna, check the isolation between
antennas and impacts of tower and roof on antennas.
For the ambient of BTS, check whether the high buildings that
are 500m away have impacts on signal transportation.

2〉 10
12 ～ 10
0.50 ～ 2
GSM
1800M
3.5〉 30
310 ～ 30
21 ～ 10
0.50 ～ 1
GSM
900M
h （ m ）D （ m ）FREQ
Installing Antenna
 When installing antenna, consider whether the ambient affects the
coverage cell. Keep the antenna away from barriers. If you need to
install antenna on the roof, try to install it on the edge.

Installing Antenna
 B. Antenna Isolation
 The receiver and transmitter must have a certain isolation.
 Isolation between antennas: Attenuation of signal from a
antenna port to another
 GSM system: The isolation between two transmitter antennas
and the isolation between the transmitter antenna and the
receiver antenna should be not fewer than 30dB.
− Antenna vertical layout: Lv=28+40log(k/λ)(dB)
− Antenna horizontal layout: Lv=22+20log(d/λ)-(G1+G2)-
(S1+S2)(dB)

 C. Requirements for Space of Diversity
 When you perform space diversity, the distance between two receiver
antennas should be 12λ to 18λ.
 When an antenna is installed highly, the horizontal space of the diversity
antenna should be large. Usually the space of diversity antenna is 0.11
times of the height of the antenna.
 To achieve the same effort, the vertical diversity space should be five to
six times of the horizontal diversity space.
 To reduce the mutual effects of two antennas, the horizontal diversity
space should be more than 3m.
Installing Antenna

Contents

 Survey report
Survey Document
 The standard survey report provides service for the subsequent
network planning and network optimization. It is the guarantee of
engineering quality and the basis of planning for network capacity.
 The survey report consists of survey table and memo.
 The survey table records the longitude and latitude of a BTS,
antenna design, and ambient.
 Shoot the picture of BTS coverage area in the direction of north.
Get eight pictures every 45°.

Illustration of Survey Document
Survey Table
Engineering Parameter Table

Surrounding of BTS
Installation platform

Og 102 site survey and layout of bts issue1.5

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