celular system

8/7/2019 celular system

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Fundamentals of CellularFundamentals of Cellular

SystemsSystems

Prepared by,

Malek Mohammed Ikram

IVth semester E.C.

C.I.T.C.


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What is Cellular Phone?

What is Cellular System?

How the Cellular System works?

Types of Cellular System.

OUTLINEOUTLINE


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What is Cellular P

hone?

What is Cellular P

hone?

A Cellular Phone is the combination of two

great technologies radio and telephone.

A Cellular Phone is basically a two-way

Walkie-talkie that acts like a telphone. With

a Walkie-talkie, you can either talk or

listen; with a cell phone, you can talk andlisten at the same time.


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In the cellular phone system, the city is divided intosmaller sections, or cells. Each cell contains its own

antenna and uses only a subset of all the channels.Each antenna is lower in height and emits a muchweaker signal so that the same subset of channelscan be used in a cell somewhere else within the city.AS the entire system is divided into group of cells it is

called Cellular System.


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Cellular System ArchitectureCellular System Architecture

Cells

Cell Splitting

Frequency Reuse

Clusters

Handoffs


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CELLSCELLS Cells are base stations transmitting

over small geographic areas that

are represented as hexagons. Each

cell size varies depending on thelandscape.

Each cell is typically sized at about

10 square miles (26 square

kilometers).

Each cell has a base station that

consists of a tower and a smallbuilding containing the radio

equipment.


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CELL

SPLITTING

CELL

SPLITTING

As a service area becomes full of

users, the Cell Splitting approach is

used to split a single area into

smaller ones. The purpose of thisdivision is to make the most use out

of a limited number of transmission

frequencies.

The genius of the cellular system is

the division of a city into small

cells. This allows extensivefrequency reuse across a city, so

that millions of people can use cell

phones simultaneously.


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FREQUEN

CY REU

SE

FREQUEN

CY REU

SE

The concept of frequency reuse is

based on assigning to each cell a

group of radio channels used within

a small geographic area. Cells areassigned a group of channels that is

completely different from

neighboring cells.

The Cellular system allocate a set

number of frequencies for each

cell. Two cells can use the samefrequency for different

conversations so long as the cells

are not adjacent to each other.


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CLU

STE

RSCLU

STE

RS A cluster is a group of

cells. No channels are

reused within a cluster


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HANDO

FFSH

ANDO

FFS Handoff occurs when

the mobile telephone

network automaticallytransfers a call from

radio channel to radio

channel as a mobile

crosses adjacent cells


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CELLUL

ART

RAN

SMISS

IONCELLUL

ART

RAN

SMISS

ION

What happens when a Cell Phone places a call?

Let's say you've just entered a phone number into your cellphone and pressed the [SND] key. Here's what happens next:

Scan Control Channels

Choose Strongest

Send Origination Message

Get Channel Assignment


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Which

is Better?Wh

ich

is Better? In analog cellular systems, the

quality of the call degrades asthe mobile phone moves further

and further away from thecellular radio station, and thereis no way to improve thequality.

low calling capacity

Limited subscribers

poor data communications

minimal privacy

inadequate fraud protection

In Digital cellular systems, thevoice signals of 1s and 0scannot be easily distorted plus

the error detectors are added toimprove the quality.

High calling capacity

Allows more number of

subscribers.

Data communication isexcellent.

More privacy

Adequate fraud protection


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Types of Cellular SystemT

ypes of Cellular System ANALOG SYSTEM AMPS

EAMPS

NAMPS

TACS

DIGITAL SYSTEM TDMA

E-TDMA

FWA

PCS

GSM

CDMA


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THANK

YOUTH

ANK

YOU

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