Site Survey and Layout of Bts Issue

Security Level:

Site Survey and Layout of BTS ISSUE 1.5 Wireless Case & Training Department

HUAWEI TECHNOLOGIES CO., LTD.

HUAWEI Confidential

www.huawei.com

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.


HUAWEI Confidential

Page 2

Purpose After learning this course, you should be familiar with:

•

Service flow of BTS survey

•

Selection of site address

•

Design of antenna


HUAWEI Confidential

Page 3

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

 Chapter 5 Survey Document


HUAWEI Confidential

Page 4

Service Description  Survey purpose

Collect the site information required by the networking planning and environment description. Check whether the site meets the requirements of construction.  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 HUAWEI TECHNOLOGIES CO., LTD.

HUAWEI Confidential

Page 5

Service Description Position of BTS survey in the network planning  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


HUAWEI Confidential

Page 6

Service Flow Radio network estimation report Obtaining site; selecting radius

Site information

Obtaining spare sites

No Whether there is a site

No Yes Whether conforming site condition

No Site survey

Whether meeting requirements of site

Yes

Yes Survey report


HUAWEI Confidential

Page 7

Electromagnetic environment test

Contents  Chapter 1 Service Description

 Chapter 2 Preparation  Chapter 3 Site Selection

 Chapter 4 Antenna Design  Chapter 5 Survey Document


HUAWEI Confidential

Page 8

Preparation  Be familiar with the engineering and collect the materials that is

related to the project :  Engineering document  Background material  Network status  Map  Configuration list


HUAWEI Confidential

Page 9

Preparation  Prepare the following tools that are

available:

 Digital camera  GPS satellite receiver

 Compass  Ruler

 Laptop


HUAWEI Confidential

Page 10

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


HUAWEI Confidential

Page 11

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


HUAWEI Confidential

Page 12

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


HUAWEI Confidential

Page 13

Principles of Selecting Site 

Principle

Population distribution Traffic distribution

Subscriber flow direction

Choosing sites in the heavy-traffic region and concentrated subscriber region

Trying not to choose sites near

Surrounding environment

mountain, radar, broadcasting

Signal propagation quality

station, forest, and electrical factory


HUAWEI Confidential

Page 14

Principles of Selecting Site  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)


HUAWEI Confidential

Page 15

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. HUAWEI TECHNOLOGIES CO., LTD.

HUAWEI Confidential

Page 16

Contents  Chapter 1 Service Description

 Chapter 2 Preparation  Chapter 3 Site Selection

 Chapter 4 Antenna Design  Chapter 5 Survey Document


HUAWEI Confidential

Page 17

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


HUAWEI Confidential

Page 18

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.


HUAWEI Confidential

Page 19

Principles of Selecting 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.


HUAWEI Confidential

Page 20

Principles of Selecting Antenna  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.


HUAWEI Confidential

Page 21

Principles of Selecting Antenna 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.


HUAWEI Confidential

Page 22

Principles of Selecting Antenna  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.


HUAWEI Confidential

Page 23

Principles of Selecting Antenna  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


HUAWEI Confidential

Page 24

Antenna Height 

Principles of Design for Antenna Height  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.


HUAWEI Confidential

Page 25

Azimuth Angle 

Principles of Design for Antenna 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. HUAWEI TECHNOLOGIES CO., LTD.

HUAWEI Confidential

Page 26

Tilt Angle 

Principles of Design for 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.


HUAWEI Confidential

Page 27

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.


HUAWEI Confidential

Page 28

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.


HUAWEI Confidential

Page 29

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.

FREQ

GSM 900M

GSM 1800M


HUAWEI Confidential

D（m）

h（m）

0～1

0.5

1～10

2

10～30

3

〉30

3.5

0～2

0.5

2～10

1

〉10

2

Page 30

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)


HUAWEI Confidential

Page 31

Installing Antenna  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.


HUAWEI Confidential

Page 32

Contents  Chapter 1 Service Description  Chapter 2 Preparation

 Chapter 3 Site Selection  Chapter 4 Antenna Design

 Chapter 5 Survey Document


HUAWEI Confidential

Page 33

Survey Document 

Survey report

 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°.


HUAWEI Confidential

Page 34

Illustration of Survey Document Engineering Parameter Table

Survey Table HUAWEI TECHNOLOGIES CO., LTD.

HUAWEI Confidential

Page 35

Surrounding of BTS

Installation platform


HUAWEI Confidential

Page 36

Thank You www.huawei.com

Site Survey and Layout of Bts Issue

Recommend Documents