OPERATION-CUM-

TOWER

TECHNICIAN

Sector: TELECOM

Occupation: Operation & maintenance

CONTENT

Objective

Introduction

Types of mobile tower

Definition of tower

Different tower pictures

Telecom tower companies

In India

Role and Responsibilities of site technician

Components of tower site

Cont… Components within the Shelter

Components within the diesel generator

Cellular network

Why external cell is used

Merits and demerits of hexagonal cell

Sectoring and process

Multiple access techniques

Generation of network (0G, 1G, 2G, 2.5G, 3G, 3.5G, 4G,

5G)

Mobile pictures of each generation of network

Cont…

GSM communication

Introduction to GSM

History of GSM

Why we go for GSM system

GSM architecture

Frequency band of GSM

Uplink and downlink frequency

Forward and reverse

Extended GSM

GSM architecture description

Handover/ handoff process

GSM channel and

Single path and multi path

Architecture of 3G network

UMTS

4G architecture network

LTP

LTE

MIMO system

OFDM block diagram

Single carrier

Multi carrier

Different heights of tower

LOC

What are the obstacles to oppose the LOC

OBJECTIVE

To understand details about mobile towers.

To study about different types of mobile tower.

To study about Shelter.

To study about Diesel Generator.

WELCOME & INTRODUCTION

A cell site or cell tower is a cellular telephone site

where antennae and electronic communications equipment are

placed, usually on a radio mast, tower or other high place, to

create a cell (or adjacent cells) in a cellular network.

Frequency reuse – same frequency in

many cell sites

Cellular expansion – easy to add new cells

Handover – moving between cells

Roaming- between networks

Cont…

The safety of cell phone towers is the subject of extensive

scientific debate.

There is a growing body of scientific evidence that the

electromagnetic radiation they emit, even at low levels, is

dangerous to human health.

Radiation from mobile phones and towers has become a

significant risk to public health in urban hubs and cities

HISTORYFirst telephone (photo phone) – Alexander Bell, 1880

The first car mounted radio telephone – 1921

1946 – First commercial mobile radio-telephone service by Bell and AT&T in Saint Louis, USA. Half duplex(PTT)

1973 – First handheld cellular phone – Motorola. 1982 „Groupe Spécial Mobile” is created within CEPT(Conférence Européenne des Postes et Télécommunications)1987 Main Radio transmission techniques are chosen, based onprototype evaluation (1986)1989 GSM becomes an ETSI technical committee1990 The Phase I GSM900 specification are frozen

DCS1800 adaptation starts1991 First systems are running

DCS 1800 specifications are frozen1992 All major European GSM 900 operators begin commercialoperations (2G)2000 3G system comes in to market.2010 4G system comes in to market.

TYPES OF MOBILE TOWER

1. Lattice Tower

It is also referred to as a self-

supporting tower.

The lattice tower affords the

greatest flexibility and is

often used in heavy loading

conditions.

It is typically three or four

sided, with similar shaped

bases.

Cont…

2. Monopole Tower

It uses minimal space and

resemble a single tube.

It requires one foundation and

typically don't exceed 50m.

The antennas are mounted on the

exterior of the tower.

Cont…

3. Guyed Tower

Guyed towers used to be the cheapest tower to construct, but require the greatest amount of land.

For taller heights (100 metres and greater) it is much cheaper to build a guyed tower.

Most radio and television towers are guyed towers.

A guyed tower is a straight tower (also referred to as mast) connected by guy wires attached to the ground in all directions, which anchor and support the tower.

Cont…4. Stealth Tower

Stealth towers are typicallyrequired by councils and at times,owners.

They are always more expensivethan the other types of towers.

More often than not they requireadditional material to "Stealth"their appearance and typicallydon't provide the same amount ofcapacity for tenants.

Cont…Based on Installation Types

•Ground Base Tower: most of telecom towers are of 40 meters in Height.

•Roof top Tower: Range 9 meter to 30 meter

Based on applicability & antenna load

• Steel lattice structure : up to 300 feet

• Monopole: up to 199 feet

• Concealed : up to 150 feet

1 feet = 0.30480 meter & 1 meter = 3 feet

DEFINITION OF TOWER

A cell tower is a cellular telephone site where antennae and electronic

communications equipment are placed, usually on a radio mast, tower

or other high place, to create a cell (or adjacent cells) in a cellular

network.

The elevated structure typically supports antennae, and one or more

sets of transmitter/receivers transreceiver, digital signal processor,

control electronics, a GPS receiver for timing (for CDMA 2000/IS-95

or GSM systems), primary and backup electrical power sources, and

sheltering.

Cont…

The working range of a cell tower or cell site (the range which

mobile devices connects reliably to the cell site) is not a fixed

figure.

It depends on a number of factors:

Height of antenna over surrounding terrain (Line-of-sight

propagation).

The frequency of signal in use.

Timing limitations in some technologies (e.g., GSM is

limited to 35 km, with 70 km being possible with special

equipment)

The transmitter's rated power.

Cont…The required uplink/downlink data rate of the

subscriber's device.

The directional characteristics of the site antenna array.

Reflection and absorption of radio energy by buildings or

vegetation.

It may also be limited by local geographical or regulatory

factors and weather conditions.

TELECOM TOWER COMPANIES IN THE

WORLDWith a portfolio of more than 1,14,101 towers, Indus is the largesttelecom tower company in the world.

IN INDIAATC India owns or operates over 12,000 tower sites throughout the country.

AircelAmerican Tower Co India LtdBharti InfratelBSNL Telecom Tower InfrastructureEssar Telecom (ETIPL)GTL InfrastructureHFCL Connect Infrastructure – Infotel GroupIdea Telecom InfrastructureIndia Telecom Infra LtdIndus Towers LtdQuippo Telecom Infrastructure Ltd [Viom Networks Ltd]Reliance InfratelTower Vision India Pvt. LtdVodafone

Cont…

ROLES & RESPONSIBILITIES OF SITE TECHNICIAN

Tower Site Maintenance

Regular Visit to site:

• Proper readings for EB, PIU…

• Check for lube oil, diesel level, water or coolant level in DG.

• Distilled water in the battery.

• Check the alarms on PIU.

Site visit in case of critical fault alert:

• Mains failure

• DG failed to start or stop.

• DG low fuel level

• Rectifier failure

• Power interface unit related

• All sensors

• Site Down

• High Temperature.

COMPONENTES OF TOWER SITE

Tower:

Platform

Mounting pole

Antenna (GSM, CDMA & Microwave)

Lightening Arrestor

Aviation Lamp

RF Feeder cable

Vertical cable tray

Earthing

Shelter:

BTS

Communication equipment rack

SMPS

Battery bank

Air Conditioning & fan unit

Sensors

Cont…Fiber connectivity box

Router/modem

Smoke detector

Anti static floor mat

Fire extinguisher etc

Diesel Generator (DG):

PIU

Power cables

Three phase & single phase system

Cut out with handle

Circuit breaker

Transformer

Auto phase selector

AC & DC panel with different meter

AMF & interlock panel

Static line conditioner (LCU)

DG battery charger

Antenna

An antenna (or aerial) is an electrical device which converts electric power into radio waves, and vice versa.

It is usually used with a radio transmitter or radio receiver.

An antenna consists of an arrangement of metallic conductors, electrically connect to the receiver or transmitter.

The first antennas were built in 1888 by German physicist Heinrich Hertz.

Cont…

According to their applications and technology available,

antennas generally fall in one of two categories:

Omni directional antenna

Directional antenna

CELLULAR NETWORK

A cellular network or mobile network is a wireless

network distributed over land areas called cells,

each served by at least one fixed-

location transceiver, known as a cell site or base

station.

In a cellular network, each cell uses a different

set of frequencies from neighbouring cells, to

avoid interference and provide guaranteed

bandwidth within each cell.

FEATURES OF CELLULAR NETWORK

More capacity than a single large transmitter, since the same frequency can be used for multiple links as long as they are in different cells

Mobile devices use less power than with a single transmitter or satellite since the cell towers are closer

Larger coverage area than a single terrestrial transmitter, since additional cell towers can be added indefinitely and are not limited by the horizon

ANTENNA MOUNTING SYSTEMS

Tower Accessories -

T-Boom Sector Mounts

SAF-T Boom

Ice Shields

Antenna Mounting Kit

Pipe to Pipe Mounting Kit

Antenna Pipes....and more

Cont…

Pole Accessories –

Tri-Collar Assemblies

Monopole Platform Kits

SAF-T-Arm

Chain Mounts

Access Ports and more..

Cont…Rooftop mounts and Accessories -

Water Tank Mounts

Tri-pod Mounts

Ballast Frames

Rooftop Bridge

Equipment Racks

BTS Platforms and more..

Transmission line support system-

Waveguide Bridge

Trapeze Kits

Pipe Post Kit

Ladder Hardware Kit

Cont…

Cable hardware and accessories –

Feeder cable

Guy Cable Hardware Kits

Bird-Flight Diverter

Galvanized Hardware

Jaw-Eye Turnbuckle

J-Bolt & U-Bolt Assembly

DIFFERENT CELL STRUCTURES

Hexagonal

Circular

Square

Triangular

FREQUENCY REUSE

The key characteristic of a cellular network is the

ability to re-use frequencies to increase both

coverage and capacity.

The adjacent cells must use different

frequencies, however there is no problem with

two cells sufficiently far apart operating on the

same frequency. The elements that determine

frequency reuse are the reuse distance and the

reuse factor.

Why hexagonal cells are used ?

Avoid the gape between the cells.

Avoid the overlap between the cells.

Cell can be easily splitting and sectoring.

More capacity in the cell.

Just look likes circular in structure.

Cont…

ADVANTAGES OF HEXAGONAL CELL

There is no overlap between adjacent cells

No gap between adjacent cells

One of their features is the efficient utilization of

spectrum resources due to frequency reuse.

In practice, frequency reuse is a defining

characteristic of cellular systems.

It exploits the fact that signal power falls of with

distance to reuse the same frequency spectrum

at spatially separated locations (cells).

DISADVANTAGEOne disadvantage of a hexagonal cell is that hexes haveadjacent cells in only six directions instead of eight, as in asquare cell.

Commonly, cells will form continuous straight lines "up" and"down", or "north" and "south", in which case the other fouradjacent cells lie "north-west", "north-east", "south-west" and"south-east".

As a result, no hex cell has an adjacent hex cell lying directly"east" or "west", making movement in a straight line east orwest somewhat more complicated than on a square cell.

Instead, paths in these directions, and any other path that doesnot bisect one of the six cell edges, will "zig-zag"; since no twodirections are orthogonal, it is impossible to move forward inone direction without moving backwards slightly in the other.

CELL SPLITTING

Cell splitting is the process of subdividing a congested cell into

smaller cells each with its own base station and a

corresponding reduction in antenna height and transmitter

power.

Cell splitting is done by defining and installing new cells which

have a smaller radius than the original cells (microcells) the

radius, R of every cell was cut in half, (R/2).

Cell splitting increases the capacity of a cellular system since

it increases the number of times that channels are reused.

The consequence of the cell splitting is that the frequency

assignment has to be done again, which affects the neighboring

cells.

CELL SECTORING

In this method, a cell has the same coverage space but instead ofusing a single Omni‐directional antenna that transmits in alldirections, either 3 or 6 directional antennas are used such that eachof these antennas provides coverage to a sector of the hexagon.

When 3 directional antennas are used, 120° sectoring is achieved ,and when 6 directional antennas are used, 60° sectoring is achieved .

Dividing the cells into sectors actually reduces the network capacitybecause the channels allocated to a cell are now divided among thedifferent sectors .

Handoff takes place when a cell phone moves from one sector toanother in the same cell. The gain in network capacity is achieved byreducing the number of interfering co‐channel cells.

If sectoring is done in a way that channels assigned to a particularsector are always at the same direction in the different cells eachsector causes interference to the cells that are in its transmissionangle only.

CELL SPLITTING & SECTORING

MULTIPLE ACCESS TECHNIQUEIn case of mobile communication, which is a form of wireless communication, theonly restraint on communication is the bandwidth restraint which means we have alimited frequency range that we can use for communication. Hence, we mustsomehow, allow multiple users communicate in the same frequency range.

Multiple Access Techniques are ways to access a single channel by multiple users.They provide multiple access to the channel. A “channel” refers to a system resourceallocated to a given mobile user enabling the user to establish communication withthe network (other users). Based on the type of channel, we can use a particularmultiple access technique for communication.

Frequency Channels [FDMA - Frequency Division Multiple Access] - Frequencyband divided into small frequency channels and different channels are allocated todifferent users – like in FM radio. Multiple users can transmit at the same time buton different frequency channels.

Time-slot Within Frequency Bands [TDMA - Time Division Multiple Access] –Each user is allowed to transmit only in specified time-slots with a commonfrequency band. Multiple users can transmit at the same frequency band at differenttimes.

Distinct Codes [CDMA - Code Division Multiple Access] – Users may transmit atthe same time using the same frequency band but using different codes so that wecan decode to identify a particular user.

FDMA

In FDMA, each user is allocated a unique frequency band or channel.

During the period of the call, no other user can share the same

frequency band.

Total frequency is divided in frequency slots.

It is a analog system.

FEATURES

Continuous transmission:- the channels are used on a non-time-

sharing basis.

Narrow band width:- Digital FDMA can make use of low bit rate

speech coding techniques to reduce the channel band even more.

Low overhead:- carry overhead messages for control

synchronization purposes.

TDMA

TDMA systems divide the channel time into frames. Each

frame is further partitioned into time slots. In each slot only

one user is allowed to either transmit or receive.

Unlike FDMA, only digital data and digital modulation must

be used.

Each user occupies a cyclically repeating time slot, so a

channel may be thought of as a particular

time slot of every frame, where

N time slots comprise a frame.

Features

Multiple channels per carrier or RF channels.

Synchronization needed.

Burst transmission since channels are used on a timesharingbasis. Transmitter can be turned off during idle periods.

Narrow or wide bandwidth – depends on factors such asmodulation scheme, number of voice channels per carrierchannel.

High ISI – Higher transmission symbol rate, hence resulting inhigh ISI. Adaptive equalizer required.

CDMA

In CDMA, the narrowband message signal is multiplied by a very large bandwidth signal called spreading signal (code) before modulation and transmission over the air. This is called spreading.

CDMA is also called DSSS(Direct sequence spread spectrum).

FEATURES:-

No frequency management

No guard time required

Enables soft handoff

CDMA example

Cont…

SPREAD SPECTRUM

Spread spectrum is a communication technique that spreads a narrow band communication signal over a wide range of frequencies for transmission and de-spreads it into the original data bandwidth at the receiver.

It uses wide band, noise like signals. Because spread spectrumsignals are noise-like ,they are hard to detect.

Spread spectrum signals are also hard to intercept or demodulate.

Further, spread spectrum signals are harder to jam(interfere with)than narrowband signals.

These low probability of intercept(LPI) and anti jam(AJ) features arewhy the military has used spread spectrum for so many years.

GENERATION (G)

0G refers pre-cellular mobile telephony technology in

1970s.

Technology used in 0G are PTT(push to talk),

MTS(mobile telephone system) & Improve-MTS.

1G TECHNOLOGY

Developed in1980 in Europe.

Based on analog

telecommunication standards.

Used analog radio signals.

It allows voice calls in one country.

Technology: AMPS, CT series

Range:2.9 kbps to 5.6 kbps.

2G TECHNOLOGY

Developed in 1990-91 in Finland.

Based on GSM technology.

Technology: GSM, CDMA, DECT…

Used digital radio signals and

SIM card.

Range: 15Kbps to 40Kbps.

GSM Services:

Tele-services

Supplementary services

Bearer services

2.5G TECHNOLOGY

General packet ratio services(GPRS)

Data rates-56kbps to115kbps

Services-

WAP

MMS and SMS

Search and directory

3G TECHNOLOGY

Based on Universal mobile telecommunication

system(UMTS).

It is known as any where, any place, any time technique.

Standards are: WiMAX, WCDMA 2000, WCDMA one,

CDMA 2000, HSPA etc

Range: (up to 2 Mbps)

144kbps to 384kbps in rural

384kbps to 27Mbps in urban

First MTNL lunched in INDIA.

3.5G TECHNOLOGY

HSDPA(high speed downlink packet access) is

referred in 3.5G.

HSPA+

Speed is up to 480kbps.

4G TECHNOLOGY

Latest and fastest generation of mobile phone

communication.

It is known as MAGIC system.

Based on 3G technology with improvements named as

LTE.

MIMO, OFDM technique used.

First used in 2009 in Sweden

First Airtel lunched in INDIA, in 2012.

Data rate: up to 20Mbps-1Gbps

5G TECHNOLOGY

Started in 2010.

Complete wireless communication

with almost no limitations.

It is highly supportable to

wwww(wireless world wide web).

Data rates more than 1Gbps.

Technology: Advanced LTE, mimo-ofdm

COMPARISON OF 1G, 2G, 3G, 4G, 5G