GSM SITE SURVEY RULES

Base Station Survey and LayoutBase Station Survey and Layout

Huawei Wireless Network Planning Department

ContentsContents

About the Service

Preparation

Coverage

Requirements

Site Selection

Antenna Design

Survey Documents

About the ServiceAbout the Service

Initial layout design of the base stations is essential to

network planning, which includes:

A. Determine the frequency multiplex mode based on

the frequency bandwidth;

B. Estimate the number of base stations in need

under the conditions such as capacity prediction,

traffic distribution and coverage requirements;

C. Determine theoretical sites of base stations;

D. Assume the relevant parameters of base stations

such as network layer structure, transmission power,

antenna feeder system, antenna type, height,

azimuth, down-tilt, etc.

About the ServiceAbout the Service

Base station site survey is a major part of determining the base

station layout, which includes optical survey, spectrum survey and

station site survey.

Optical survey

The construction environment and

natural environment surrounding

the base stations.

Spectrum survey

Electromagnetic environment

Station site survey

Installation environment for antennas

and equipment

Power supply and transmission facilities

ContentsContents

About the Service

Preparation

Coverage Requirement

s

Site Selection

Antenna Design

Survey Documents

Get familiar with the project, and try to collect various materials

concerned, including:

Engineering documents

Background materials

Information about existing

network

Local map, etc.

Contract configuration list

The latest site survey table

of network planning

PreparationPreparation

Prepare tools, and ensure they work normally

before setting out;

Digital camera

GPS satellite receiver

Compass

Ruler

Portable computer


Base Station site Survey Preparation Meeting Base Station site Survey Preparation Meeting


Before survey, all the persons concerned shall gather in the survey preparation & coordination meeting to discuss the following details:

Electromagnetic background, and to test the electromagnetic background when necessary;

Arrangement of people responsible for survey and cooperation; Vehicle and equipment preparation; Make a survey plan and

determine the survey routes; Elementary project concerning transmission,

power supply, etc.

ContentsContents

About the Ser

vice

Preparation

Coverage Req

uirements

Site Selection

Antenna Desig

n

Survey Docum

ents

Coverage RequirementsCoverage Requirements

Coverage of a base station mainly

depends on the following factors:

Service quality indices

Output power of the transmitter

Available sensitivity of the receiver

Antenna orientation and gain

Frequency band in use

Promulgation environment

Application of diversity reception

......

ContentsContents

About the Ser

vice

Preparation

Coverage Req

uirements

Site Selection

Antenna Desig

n

Survey Docum

ents

Site SelectionSite Selection

After preparation and getting informed of coverage

requirements, you can select the base station site. During

determining station site, the following factors shall be taken into

consideration: The existing network Population distribution and local

customs City structure and town chorology Major streets and traffic Mountains, lakes, rivers, coastlines Nature environment Long-term development trend, etc.


Select areas with dense

traffic and subscribers

Population distribution

Traffic distribution

Subscriber flowing tread

Principles for Base Site Selection Principles for Base Site Selection

Base station surroundings

Signal transmission quality

Be careful when choosing

mountains or those near to

radars, radio station, forest,

power supply factory, etc.

Principles for base station site selection:

A. Try to locate the base station at an ideal position in the regular

cellular meshes, and the error shall not exceed one-fourth of the site

radius;

B. Try to make use of existing facilities without prejudice to the base

station layout, cutting down the construction cost and period;

C. Normally, do not select mountains with

high elevations at the edges of cities or in

suburbs (100~300 meters or higher than

the elevation of the cities or suburbs) for

the convenience of coverage control and

maintenance, and reducing the difficulty of

project construction;



D. Base station should be constructed in a safe place with convenient traf

fic, mains power supply and without occupying too many fertile farmlands;

E. Try not to construct the base station near a high power radio transmiss

ion station, radar station or other interference sources;

F. Base station to be constructed shall be far from woods to avoid rapid a

ttenuation of signals;

G. When constructing a base station in an area with mountains, cliffy ban

ks, or many lakes, or in a hilly city, or in a high metal building, you must c

onsider the influence of signal reflection and time dispersion;

H. When constructing a base station among buildings, you can make use

of the height of buildings to realize the division of network layer structure;

I. When there are only a few stations at the beginning of construction, it is

required to ensure good coverage in important areas.

ContentsContents

About the Service

Preparation

Coverage Require

ments

Site Selection

Antenna Feeder D

esign

Survey Document

s

Introduction to Antenna Feeder System Introduction to Antenna Feeder System

Antenna Feeder System-Combining and Distribution UnitAntenna Feeder System-Combining and Distribution Unit

The antenna feeder system is composed of combining and distribution unit,

feeder, tower top amplifier, and antenna:

Combining and distribution unit

Function:

Mainly for receipt and sending of signal duplex, transmission of signal

combining, filtering, receipt of signal filtering, low noise amplification

and distribution, provision of feed circuit of tower top amplifier;

realization of multiple transmission signals and common use of the units

of one antenna by several received signals.

Type:

At present, Huawei can provide the following combining and distribution

units: SCU, CDU, EDU, etc.

Antenna Feeder System—Combining and Distribution UnitAntenna Feeder System—Combining and Distribution Unit

Comparison of Insertion Loss of Combining and Distribution Units: Comparison of Insertion Loss of Combining and Distribution Units:

5.14.54.3CDU+CDU

8.287.3CDU+SCU

5.14.54.3CDU

1.2510.7Dual CDU(without via combiner)

1.2510.7EDU

MaximumTypical ValueMinimum

Transmission Channel Loss (dB)Type of Combiner

Antenna Feeder System—Tower Top AmplifierAntenna Feeder System—Tower Top Amplifier

Tower Top Amplifier

Function: Improves the sensitivity of base station receipt system.

Type: As an alternative, the tower top amplifier shall be selected

according to the frequency band used in the system. The base station with CDU pattern may use simplex tower

top amplifier and triplex tower top amplifier; the base station with combiner mode shall use duplex tower top amplifier;

Antenna Feeder System—FeederAntenna Feeder System—Feeder

Feeder:

Frequently-used specification: ½", 7/8 ", 5/4 "

How to choose a feeder: Use 5/4 “ feeders for 900MHz and over 80 meters of length; 5/4″feeders for 1800MHz and over 50 meters of length; The curvature of the feeders shall not be too large, and the

conductor surface is required to well connected with the ground.

feeder loss: 900M: Approximate 5dB/100m on 7/8″feeders; about 3dB/100m

on 5/4″feeders. 1800M: : Approximate 6dB/100m on 7/8″feeders; about

4dB/100m on 5/4″feeders.

Antenna Feeder System—AntennaAntenna Feeder System—Antenna

Antenna

GSM mobile communication system often adopts directional an

tenna with a horizontal beam width of 90°or 65° and omnidirecti

onal antenna based on the shape or range of the service area,

channel number and other conditions;

For Indoor coverage or tunnel coverage with micro cells, and ot

her special conditions, distributed antenna and leakage cables

may be used; for city-concentrated area, in order to decrease i

nterference to the adjacent cells, 65°antenna is adopted normal

ly; in a suburb with a small number of subscribers, 90°direction

al antenna or omnidirectional antenna is adopted; at present, th

e following company’s are in use: Kathrein, Allgon, Xi’an Haitia

n, Andrew, etc.


Antenna has many performance indices, of which the

following items are the most important for network

planning:

Frequency Range

Gain

Polarization

Horizontal/Vertical half-power beam width

Down-tilt

Antenna Performance Indices: Antenna Performance Indices:


For example, the direction figures of Kathrein 739649 directional antenna are as follows:


The direction figures for Andrew CT1D0F-0087-011 Omnidirectional Antenna are as follows:

Antenna Feeder System - AntennaAntenna Feeder System - Antenna

Performance of Frequently-used Indoor Antennas

Performance of Frequently-used Indoor Antennas

Distributed Antenna System Distributed Antenna System


With the development of GSM system, subscribers raise more and more requirements on mobile communication network. Good coverage in large buildings, highways/ railway tunnels, metros, and other special areas requires distributed antenna system;

Distributed antenna system consists of leakage cable, coaxial feeder distributed antenna, optical fiber feeder distributed antenna, etc.;

Antenna Feeder Design Antenna Feeder Design

Antenna Feeder DesignAntenna Feeder Design

The antenna feeder configuration plan is worked out based on operators’

requirements on coverage and capacity, and in the light of detailed type

configuration, installation environment and other practical conditions of a

certain base station.

Selection of Combiner

Normally depends on the coverage requirements of a base station, by

giving consideration to network development tendency;

Selection of feeders

The type of feeders is mainly determined according to the length of lines

in need;

Selection of tower top amplifier

During tower top amplifier configuration, the coverage radius of cells

may be increased;

How to Choose An Antenna How to Choose An Antenna

Antenna Feeder Design—How to Choose An AntennaAntenna Feeder Design—How to Choose An Antenna

How to Choose An Antenna is an important part that may

determine the network quality;

Antenna shall be selected as per the coverage and service

quality requirements within the base station service area,

traffic distribution, topographic and landforms conditions, with

consideration to the coverage and interference details of the

entire network;

The environment for the use of antennas may be divided into

the following types according to the topographic conditions or

traffic distribution:

Urban, suburb, rural area, highway, hilly area, coastal

area, tunnel, indoor, etc.

Antenna Feeder Design - How to Choose An AntennaAntenna Feeder Design - How to Choose An Antenna

How to Choose An Antenna for Urban Base Stations

A. Generally, directional antenna with a horizontal half-power angle of 6

0～ 65°is used;

B. Normally, antenna with a medium gain at about 15dBi is used;

C. It’s better to select antenna with a certain electric Down-tilt (3～ 6°);

D. Bipolarization antenna is suggested.

Antenna for Suburban Base Stations

A. Whether to use directional antenna with a horizontal half-power angle o

f 65°or 90° is determined by the practical conditions;

B. Normally, antenna with middle or high gain at about 15 ～ 18dBi is sele

cted;

C. Whether to adopt preseted Down-tilt shall be determined on the basis o

f practical conditions;

D. Bipolarization or vertically polarized antenna can be used.

Antenna Feeder Design—How to Choose An AntennaAntenna Feeder Design—How to Choose An Antenna

Antenna for Rural Base Stations A. 90°or 120°directional antenna or omnidirectional antenna can

be used according to the practical conditions and requirements; B. The gain of the selected directional antenna is normally high

(16～ 18dBi); C. Normally, preseted Down-tilt antenna is not used; zero filling

antenna can be selected in prior for high stations; D. Vertically polarized antenna is suggested.

Antenna for Highway Base Stations A. Generally, directional antenna with narrow wave beam and hi

gh gain is used, or an 8-shaped antenna, omnidirectional antenna or deformed omnidirectional antenna according to the practical conditions;

B. As highway base stations require longer coverage, generally, preseted Down-tilt antenna is not applied;

C. Vertically polarized antenna is suggested; D. It is appropriate not to select the directional antenna with too l

arge front to rear ratio.

Antenna Feeder Design—Antenna HeightAntenna Feeder Design—Antenna Height

The antennas for different cells within one base station can be of different heights,

which may be restricted by the installation space in a certain direction or required

by cell planning;

In urban areas with smooth terrain, the effective height for ordinary antennas shall

be at about 25m;

For suburban and rural base stations, the heights of antennas can be increased to

about 40m.

Too high antenna may decrease the coverage

level near the antenna (which is known as

Under-Tower Black); the problem of an

omnidirectional one is extremely serious;

Too high antenna may result in serious

problems such as handover coverage,

same/neighboring frequency interference,

and affect the network quality.

Principle for Determining Antenna Height Principle for Determining Antenna Height

Principle for Determining Antenna azimuth Angle Principle for Determining Antenna azimuth Angle

Antenna Feeder Design—Direction AngleAntenna Feeder Design—Direction Angle

The antenna azimuth angle shall be determined from the entire network. Providing meetin

g the coverage requirements, try to ensure identical angles of the three sectors of each ba

se station in the urban area with partial trimming; for the base station in the connection are

a of urban and rural areas, communication trunk roads, and suburban isolation stations, th

e direction angle of antenna shall be adjusted according to the important coverage objects.

The main lobe of antenna shall point at the area with densely concentrated traffic to streng

then the signal intensity in that area and improve the conversation quality;

The main lobe of the antenna shall be kept away from the same frequency cell to effectivel

y decrease interference;

The cross coverage depth of the antennas in neighboring sectors in an urban area shall no

t exceed 10%;

The cross coverage depth of neighboring cells in a suburb area, or rural area shall not be t

oo large; the angle of the antennas in neighboring sectors within the same base station sh

all not be less than 90°;

To avoid handover coverage, in the area with thickly concentrated cities, the main lobe of

antenna shall orient straighter streets.

Principle for Determining Antenna Down-tilt Principle for Determining Antenna Down-tilt

Antenna Feeder Design—Down-tiltAntenna Feeder Design—Down-tilt

The wave beam tilt of antenna is a basic technology to improve fre

quency multiplex capability;

To adopt antenna Down-tilt technology can effectively control the

coverage and decrease the interference within the system;

The antenna Down-tilt angle shall be determined according to the

practical conditions so as to decrease the interference between ce

lls of the same frequency and to ensure meeting the coverage req

uirements;

Down-tilt determination shall give overall consideration to the trans

mission power of the base station, height of the antenna, cell cove

rage, wireless broadcast environment, and other factors;

Antenna Feeder Design—Down-tilt Antenna Feeder Design—Down-tilt

Antenna wave beam tilt can adopt electric or mechanical pattern: The

electric Down-tilt is related to the mode of the antenna selected;

normally, it is fixed; mechanical Down-tilt can be adjusted but will be

limited by installation fittings and wireless signal spread features;

normally, it shall not exceed 15°;

Electric Down-tilt and mechanical Down-tilt may lead to different

surface radiation; when the Down-tilt is small, there is little difference;

but with the increase of Down-tilt, the difference becomes bigger:

Notes for Antenna Installation: Notes for Antenna Installation:

Antenna Feeder Design—Antenna InstallationAntenna Feeder Design—Antenna Installation

A. Installation environment The installation environment includes the surroundings near the antenna

and near the base station. The surroundings near the antenna mainly

consider the isolation between antennas, and the influence of iron

towers and buildings on antennas; the surroundings near the base

station mainly consider the influence of high buildings lower than 500

meters on radio signal transmission.

2〉 10

12～ 10

0.50～ 2GSM

1800M

3.5〉 30

310～ 30

21～ 10

0.50～ 1

GSM900M

h (m)D (m)FREQ


During the installation of base station antennas, it is required to notice

whether they may lead to big shadow in the coverage area, and to be kept

away from obstacle, for example, in the installation of antennas on the top of

a building, you should make sure no obstacle against radio signal on the top,

and try to install the antennas near the edge


B. Antenna Isolation

The receiver and transmitter of the base station shall be isolat

ed in a certain degree;

Isolation between antennas: The attenuation of signals from o

ne port of an antenna to that of the other one in actual installa

tion of antenna;

GSM system: The isolation between two transmitting antenna

s and between the transmitting and receiving antennas shall

be 30dB at least;

Antenna vertical layout: Lv=28+40log(k/λ)(dB)

Antenna horizontal layout: Lv=22+20log(d/λ)-(G1+G2)-(S

1+S2)(dB)

C. Meet the distance requirements for space diversity gain

For space diversity, the distance between two receiving antennas is required t

o be 12～ 18λ;

The higher the antenna is installed, the bigger the horizontal distance between

diversity antennas is; normally, the diversity horizontal distance shall be equal

0.11 time of the effective height of the antenna;

To achieve the same diversity effect, vertical diversity distance shall be 5~6 ti

mes of the horizontal diversity distance;

To reduce the inter influence

of two antennas, the diversity

antenna horizontal distance

at any effective height of

antenna shall be over 3m.


ContentsContents

About the Service

Preparation

Coverage Requirement

s

Site Selection

Antenna Feeder Design

Survey Documents

Base Station Survey Report Base Station Survey Report

Survey DocumentsSurvey Documents

Accurate and standard documents are of much help for further network planning and optimization work. They are a powerful guaranty to the project quality and the basis for future network expansion planning.

Base station survey report includes base station survey table and memo;

Each base station has one survey table which mainly records the longitude, latitude, antenna feeder design, surroundings, and other details; (See Remarks)

Thank You!