OPERATION-CUM-TOWER

TECHNICIAN

Sector: TELECOMOccupation: Operation & maintenance

CONTENT Objective Introduction Types of mobile tower

Definition of towerDifferent tower pictures

Telecom tower companiesIn 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

LTEMIMO 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

HISTORY First 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 on prototype

evaluation (1986) 1989 GSM becomes an ETSI technical committee 1990 The Phase I GSM900 specification are frozen

DCS1800 adaptation starts 1991 First systems are running

DCS 1800 specifications are frozen 1992 All major European GSM 900 operators begin commercial operations

(2G) 2000 3G system comes in to market. 2010 4G system comes in to market.

TYPES OF MOBILE TOWER1. 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 typically required by councils and at times, owners.

They are always more expensive than the other types of towers.

More often than not they require additional material to "Stealth" their appearance and typically don't provide the same amount of capacity 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 WORLD With a portfolio of more than 1,14,101 towers, Indus  is the largest telecom tower

company in the world. 

IN INDIA ATC India owns or operates over 12,000 tower sites throughout the country. Aircel

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

Cont…

ROLES & RESPONSIBILITIES OF SITE TECHNICIAN

Tower Site MaintenanceRegular 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 EarthingShelter: 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 etcDiesel 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 MountsSAF-T BoomIce ShieldsAntenna Mounting KitPipe to Pipe Mounting KitAntenna 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 MountsTri-pod MountsBallast FramesRooftop BridgeEquipment RacksBTS Platforms and more..

Transmission line support system-Waveguide BridgeTrapeze KitsPipe Post KitLadder Hardware Kit

Cont… Cable hardware and accessories –

Feeder cableGuy Cable Hardware KitsBird-Flight DiverterGalvanized HardwareJaw-Eye TurnbuckleJ-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).

DISADVANTAGE One disadvantage of a hexagonal cell is that hexes have adjacent

cells in only six directions instead of eight, as in a square cell. Commonly, cells will form continuous straight lines "up" and

"down", or "north" and "south", in which case the other four adjacent 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 or west somewhat more complicated than on a square cell.

Instead, paths in these directions, and any other path that does not bisect one of the six cell edges, will "zig-zag"; since no two directions are orthogonal, it is impossible to move forward in one 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 of using

a single Omni‐directional antenna that transmits in all directions, either 3 or 6 directional antennas are used such that each of 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 capacity because the channels allocated to a cell are now divided among the different sectors .

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

If sectoring is done in a way that channels assigned to a particular sector are always at the same direction in the different cells each sector causes interference to the cells that are in its transmission angle only.

CELL SPLITTING & SECTORING

MULTIPLE ACCESS TECHNIQUE In case of mobile communication, which is a form of wireless communication, the only

restraint on communication is the bandwidth restraint which means we have a limited frequency range that we can use for communication. Hence, we must somehow, 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 resource allocated to a given mobile user enabling the user to establish communication with the network (other users). Based on the type of channel, we can use a particular multiple access technique for communication.

Frequency Channels [FDMA - Frequency Division Multiple Access] - Frequency band divided into small frequency channels and different channels are allocated to different users – like in FM radio. Multiple users can transmit at the same time but on 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 common frequency band. Multiple users can transmit at the same frequency band at different times.

Distinct Codes [CDMA - Code Division Multiple Access] – Users may transmit at the same time using the same frequency band but using different codes so that we can 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 timesharing basis. Transmitter can be turned off during idle periods.

Narrow or wide bandwidth – depends on factors such as modulation scheme, number of voice channels per carrier channel.

High ISI – Higher transmission symbol rate, hence resulting in high 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 spectrum signals 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 are why 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