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Mobile Communications: Introduction

Mobile Communications

Chapter 1: Introduction

A case for mobility

History of mobile communication

MarketAreas of research

1.0.1


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Computers for the next century?

Computers are integrated

small, cheap, portable, replaceable - no more separate devicesTechnology in the background

computer are aware of their environment and adapt (location

awareness)

computer recognize the location of the user and react appropriately

(e.g., call forwarding, fax forwarding)Advances in technology

more computing power in smaller devices

flat, lightweight displays with low power consumption

new user interfaces due to small dimensions

more bandwidth per cubic meter multiple wireless interfaces: wireless LANs, wireless WANs,

regional wireless telecommunication networks etc. (overlay

networks)

1.1.1


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Mobile communication

Aspects of mobility:

user mobility: users communicate (wireless) anytime, anywhere, withanyone

device portability: devices can be connected anytime, anywhere to the

network

Wireless vs. mobile Examples stationary computer notebook in a hotel wireless LANs in historic buildings Personal Digital Assistant (PDA)

The demand for mobile communication creates the need for

integration of wireless networks into existing fixed networks:

local area networks: standardization of IEEE 802.11,ETSI (HIPERLAN)

Internet: Mobile IP extension of the internet protocol IP

wide area networks: e.g., internetworking of GSM and ISDN

1.2.1


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Applications I

Vehicles

transmission of news, road condition, weather, music via DAB personal communication using GSM

position via GPS

local ad-hoc network with vehicles close-by to prevent accidents,

guidance system, redundancy

vehicle data (e.g., from busses, high-speed trains) can betransmitted in advance for maintenance

Emergencies

early transmission of patient data to the hospital, current status, first

diagnosis

replacement of a fixed infrastructure in case of earthquakes,hurricanes, fire etc.

crisis, war, ...

1.3.1


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Typical application: road traffic

UMTS, WLAN,

DAB, GSM,

TETRA, ...

Personal Travel Assistant,

DAB, PDA, laptop,

GSM, UMTS, WLAN,

Bluetooth, ...

1.4.1


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Applications II

Travelling salesmen

direct access to customer files stored in a central location consistent databases for all agents

mobile office

Replacement of fixed networks

remote sensors, e.g., weather, earth activities

flexibility for trade shows LANs in historic buildings

Entertainment, education, ...

outdoor Internet access

intelligent travel guide with up-to-date

location dependent information

ad-hoc networks for

multi user games

1.5.1


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Location dependent services

Location aware services

what services, e.g., printer, fax, phone, server etc. exist in the localenvironment

Follow-on services

automatic call-forwarding, transmission of the actual workspace to

the current location

Information services push: e.g., current special offers in the supermarket

pull: e.g., where is the Black Forrest Cherry Cake?

Support services

caches, intermediate results, state information etc. follow the

mobile device through the fixed networkPrivacy

who should gain knowledge about the location

1.6.1


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Mobile devices

performance

Pager

receive only

tiny displayssimple text

messages

Mobile phones

voice, data

simple text displays

PDA

simple graphical displays

character recognitionsimplified WWW

Palmtop

tiny keyboard

simple versions

of standard applications

Laptop

fully functional

standard applications

1.7.1

Sensors,

embedded

controllers


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Effects of device portability

Power consumption

limited computing power, low quality displays, small disks due to

limited battery capacity

CPU: power consumption ~ CV2f

C: internal capacity, reduced by integration

V: supply voltage, can be reduced to a certain limit

f: clock frequency, can be reduced temporally

Loss of data higher probability, has to be included in advance into the design

(e.g., defects, theft)

Limited user interfaces

compromise between size of fingers and portability

integration of character/voice recognition, abstract symbols

Limited memory

limited value of mass memories with moving parts

flash-memory or ? as alternative

1.8.1


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Wireless networks in comparison to fixed networks

Higher loss-rates due to interference

emissions of, e.g., engines, lightning

Restrictive regulations of frequencies

frequencies have to be coordinated, useful frequencies are almost

all occupied

Low transmission rates

local some Mbit/s, regional currently, e.g., 9.6kbit/s with GSMHigher delays, higher jitter

connection setup time with GSM in the second range, several

hundred milliseconds for other wireless systems

Lower security, simpler active attacking

radio interface accessible for everyone, base station can besimulated, thus attracting calls from mobile phones

Always shared medium

secure access mechanisms important

1.9.1


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Early history of wireless communication

Many people in history used light for communication

heliographs, flags (semaphore), ...

150 BC smoke signals for communication;

(Polybius, Greece)

1794, optical telegraph, Claude Chappe

Here electromagnetic waves are

of special importance:

1831 Faraday demonstrates electromagnetic induction J. Maxwell (1831-79): theory of electromagnetic Fields, wave

equations (1864)

H. Hertz (1857-94): demonstrates

with an experiment the wave character

of electrical transmission through space(1886, in Karlsruhe, Germany, at the

location of todays University of Karlsruhe)

1.10.1


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History of wireless communication I

1895 Guglielmo Marconi

first demonstration of wirelesstelegraphy (digital!)

long wave transmission, high

transmission power necessary (> 200kw)

1907 Commercial transatlantic connections

huge base stations(30 100m high antennas)

1915 Wireless voice transmission New York - San Francisco

1920 Discovery of short waves by Marconi

reflection at the ionosphere

smaller sender and receiver, possible due to the invention of thevacuum tube (1906, Lee DeForest and Robert von Lieben)

1926 Train-phone on the line Hamburg - Berlin

wires parallel to the railroad track

1.11.1


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History of wireless communication II

1928 many TV broadcast trials (across Atlantic, color TV, TV news)

1933 Frequency modulation (E. H. Armstrong)1958 A-Netz in Germany

analog, 160MHz, connection setup only from the mobile station, no

handover, 80% coverage, 1971 11000 customers

1972 B-Netz in Germany

analog, 160MHz, connection setup from the fixed network too (butlocation of the mobile station has to be known)

available also in A, NL and LUX, 1979 13000 customer in D

1979 NMT at 450MHz (Scandinavian countries)

1982 Start of GSM-specification

goal: pan-European digital mobile phone system with roaming

1983 Start of the American AMPS (Advanced Mobile Phone

System, analog)

1984 CT-1 standard (Europe) for cordless telephones

1.12.1


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History of wireless communication III

1986 C-Netz in Germany

analog voice transmission, 450MHz, hand-over possible, digital

signaling, automatic location of mobile device

still in use today (as T-C-Tel), services: FAX, modem, X.25, e-mail,

98% coverage

1991 Specification of DECT

Digital European Cordless Telephone (today: Digital Enhanced

Cordless Telecommunications) 1880-1900MHz, ~100-500m range, 120 duplex channels, 1.2Mbit/s

data transmission, voice encryption, authentication, up to several

10000 user/km2, used in more than 40 countries

1992 Start of GSM

in D as D1and D2, fully digital, 900MHz, 124 channels automatic location, hand-over, cellular

roaming in Europe - now worldwide in more than 100 countries

services: data with 9.6kbit/s, FAX, voice, ...

1.13.1
http://www.t-mobil.de/http://www.dect.ch/http://www.t-mobil.de/http://www.d2privat.de/http://www.d2privat.de/http://www.t-mobil.de/http://www.dect.ch/http://www.t-mobil.de/http://www.t-mobil.de/http://www.t-mobil.de/http://www.t-mobil.de/http://www.t-mobil.de/


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History of wireless communication IV

1994 E-Netz in Germany

GSM with 1800MHz, smaller cells, supported by 11 countries

as Eplusin D (1997 98% coverage of thepopulation)

1996 HiperLAN (High Performance Radio Local Area Network)

ETSI, standardization of type 1: 5.15 - 5.30GHz, 23.5Mbit/s

recommendations for type 2 and 3 (both 5GHz) and 4 (17GHz) as

wireless ATM-networks (up to 155Mbit/s)1997 Wireless LAN - IEEE802.11

IEEE-Standard, 2.4 - 2.5GHz and infrared, 2Mbit/s

already many products (with proprietary extensions)

1998 Specification of GSM successors

for UMTS (Universal Mobile Telecommunication System) asEuropean proposals for IMT-2000

Iridium

66 satellites (+6 spare), 1.6GHz to the mobile phone

1.14.1
http://www.eplus.de/http://www.etsi.fr/http://standards.ieee.org/http://www.itu.int/imthttp://www.iridium.com/http://www.iridium.com/http://www.itu.int/imthttp://www.itu.int/imthttp://www.itu.int/imthttp://standards.ieee.org/http://standards.ieee.org/http://standards.ieee.org/http://www.etsi.fr/http://www.eplus.de/


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Wireless systems: overview of the development

cellular phones satellites wireless

LAN

cordless

phones

1992:

GSM

1994:

DCS 1800

2005?:

UMTS/IMT-2000

1987:

CT1+

1982:

Inmarsat-A

1992:

Inmarsat-B

Inmarsat-M

1998:

Iridium

1989:

CT 2

1991:

DECT

199x:proprietary

1995/96/97:

IEEE 802.11,

HIPERLAN

2005?:

MBS, WATM

1988:

Inmarsat-C

analog

digital

1.15.1

1991:

D-AMPS

1991:

CDMA

1981:

NMT 450

1986:

NMT 900

1980:

CT0

1984:

CT11983:

AMPS

1993:

PDC


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The future: ITU-R - Recommendations for IMT-2000

M.687-2

IMT-2000 concepts and goals

M.816-1

framework for services

M.817

IMT-2000 network architectures

M.818-1

satellites in IMT-2000

M.819-2

IMT-2000 for developing countries

M.1034-1

requirements for the radio

interface(s)

M.1035

framework for radio interface(s) and

radio sub-system functions

M.1036

spectrum considerations

M.1078

security in IMT-2000

M.1079

speech/voiceband data performance

M.1167

framework for satellites

M.1168

framework for management

M.1223

evaluation of security mechanisms

M.1224

vocabulary for IMT-2000

M.1225

evaluation of transmission technologies

. . .

http://www.itu.int/imt

1.16.1
http://www.itu.int.imt/http://www.iut.int/imthttp://www.itu.int.imt/http://www.itu.int.imt/


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Worldwide wireless subscribers (prediction)

0

100

200

300

400

500

600

700

1996 1997 1998 1999 2000 2001

Americas

Europe

Japan

others

total

1.17.1


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Mobile phones per 100 people 1997

1998: 40% growth rate in Germany

1.18.1

0 10 20 30 40 50

France

Germany

Western Europe

Spain

UK

Italy

USA

Japan

Denmark

Finland


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Areas of research in mobile communication

Wireless Communication

transmission quality (bandwidth, error rate, delay) modulation, coding, interference

media access, regulations

...

Mobility

location dependent services location transparency

quality of service support (delay, jitter, security)

...

Portability

power consumption

limited computing power, sizes of display, ...

usability

...

1.19.1


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Simple reference model used here

1.20.1

Application

Transport

Network

Data Link

Physical

Medium

Data Link

Physical

Application

Transport

Network

Data Link

Physical

Data Link

Physical

Network Network

Radio


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Influence of mobile communication to the layer model

service location

new applications, multimedia

adaptive applications

congestion and flow control

quality of service

addressing, routing,

device location

hand-over authentication

media access

multiplexing

media access control

encryption

modulation

interference

attenuation

frequency

Application layer

Transport layer

Network layer

Data link layer

Physical layer

1.21.1


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Overview of the chapters

Chapter 2:

Wireless Transmission

Chapter 3:Medium Access Control

Chapter 4:

Telecommunication

Systems

Chapter 5:

Satellite

Systems

Chapter 6:

Broadcast

Systems

Chapter 7:

Wireless

LAN

Chapter 8:

Wireless

ATM

Chapter 9:

Mobile Network Layer

Chapter 10:

Mobile Transport Layer

Chapter 11:

Support for Mobility

1.22.1


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Overlay Networks - the global goal

regional

metropolitan area

campus-based

in-house

vertical

hand-over

horizontal

hand-over

integration of heterogeneous fixed and

mobile networks with varying

transmission characteristics

1.23.1


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Mobile Internet Commuication Technologies

Cellular technology is one of the fastest and ongoing growing

telecommunication industries of the world.Currently we have following

mobile and internet communication technologies adopted by different

mobile companies in different parts of the world.

GSM

CDMA

EDGE

GPRS

VOIP

Mobile Communications:Technologies


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Mobile Internet Communication Technologies - GSM

Global System for Mobile Communication (GSM)

GSM is a cellular network, which means that mobile phones connect to it

by searching for cells in the immediate vicinity. GSM technology

facilitates with high speed integrated data; voice data, fax, mail, voice

mail and mostly used SMS feature.

GSM criteria

Good subjective speech quality

Low terminal and service cost

Support for international roamingone system for all of Europe

Ability to support handheld terminals

Support for range of new services and facilities

Enhanced Features

ISDN compatibility

Enhance privacy

Security against fraud

Mobile Communications: GSM


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Building Blocks :

1.AMPSAdvanced Mobile Phone System

analog technology

used in North and South America and approximately 35 othercountries

operates in the 800 MHz band using FDMA technology

2. TACSTotal Access Communication System

variant of AMPS

deployed in a number of countries

primarily in the UK

3. NMTNordic Mobile Telephone System

analog technology

deployed in the Benelux countries and Russia operates in the 450 and 900 MHz band

first technology to offer international roamingonly within the Nordiccountries



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System Architecture

1. Mobile Station (MS)Mobile Equipment (ME)

Subscriber Identity Module (SIM)

2. Base Station Subsystem (BBS)

Base Transceiver Station (BTS)

Base Station Controller (BSC)3. Network Subsystem

Mobile Switching Center (MSC)

Home Location Register (HLR)

Visitor Location Register (VLR)

Authentication Center (AUC)Equipment Identity Register (EIR)



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Mobile Stations1.Mobile Equipment

Produced by many different manufacturers Must obtain approval from the standardization body

Uniquely identified by an IMEI (International Mobile

Equipment Identity)

Mobile Stations -2. Subscriber Identity Module (SIM)

Smart card containing the International Mobile SubscriberIdentity (IMSI)

Allows user to send and receive calls and receive othersubscribed services

Encoded network identification details

Protected by a password or PIN Can be moved from phone to phonecontains key

information to activate the phone



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Base Station Subsystem- 1.Base Transceiver Station (BTS)

Houses the radio transceivers that define a cell

Handles radio-link protocols with the Mobile Station

Speech and data transmissions from the MS are recoded

Requirements for BTS:

ruggedness

reliability

portability minimum costs

Base Station Subsystem- 2. Base Station Controller (BSC)

Manages Resources for BTS

Handles call set up Location update

Handover for each MS



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Network Subsystem-1. Mobile Switching Center (MSC)

Switch speech and data connections between:

Base Station Controllers Mobile Switching Centers

GSM-networks

Other external networks

Heart of the network

Three main jobs:

1. connects calls from sender to receiver

2. collects details of the calls made and received

3. supervises operation of the rest of the network components

Network Subsystem-2. Home Location Registers (HLR)

contains administrative information of each subscriber current location of the mobile



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Network Subsystem3. Visitor Location Registers (VLR)

contains selected administrative information from the HLR

authenticates the user

tracks which customers have the phone on and ready to receive a call

periodically updates the database on which phones are turned on and

ready to receive calls

Network Subsystem4. Authentication Center (AUC)

mainly used for security

data storage location and functional part of the network

Ki is the primary element

Network Subsystem5. Equipment Identity Register (EIR)

Database that is used to track handsets using the IMEI (International

Mobile Equipment Identity) Made up of three sub-classes: The White List, The Black List and the

Gray List

Optional database



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Features:

Calling Line ID - incoming telephone number displayed

Alternate Line Service

- one for personal calls

- one for business calls

Closed User Group - call by dialing last for numbers

Advice of Charge - tally of actual costs of phone calls

Fax & Data - Virtual Office / Professional OfficeRoaming - services and features can follow customer from market to

market

Call Waiting - Notification of an incoming call while on the handset

Call Hold - Put a caller on hold to take another call

Call Barring - All calls, outgoing calls, or incoming callsCall Forwarding - Calls can be sent to various numbers defined by the user

Multi Party Call Conferencing - Link multiple calls together



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Architecture of a GSM Network

Mobile Communications:GSM

SD

Mobile Station

BTS

MSC/

VLR

SIM

ME

BSC

Base Station

Subsystem

GMSC

Network Subsystem

AUCEIR HLR

Other Networks

Note: Interfaces have been omitted for clarity purposes.

+

PSTN

PLMN

Internet


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Mobile Internet Communication Technologies - CDMA

CDMA (Code Division Multiple Access) splits calls into fragments and send

them over different frequencies simultaneously

The use of multiple frequencies gives CDMA effective protection against

interference and lost calls

CDMA supports true packet switching and does not use time slots,

therefore is more bandwidth efficient than TDMA -- also a more direct

path to 3GCurrent CDMA penetration in the world market is about 27%

Mobile Communications: CDMA


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CDMA2000-1xEVDO System Architecture (Basic)

BTS: Base Station, which creates a single cell

BSC: Base Station Controller, which controls roaming and channelallocations amongst various BSTs and is also referred to as a Radio

Network Controller (RNC).

MSC: Mobile Switching Center, which performs the telephony switchingfunctions and is usually connected to an SS7 network.

PDSN: Packet Data Serving Node, maintains IP communications between

all MNs and the Packet Data Network (PDN), which in this diagram is theInternet.



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There is no restriction on time and frequency in this scheme.

All the users can transmit at all times and at all frequencies.

Because users are isolated by code, they can share the same carrier

frequency, eliminating the frequency reuse problem encountered in

other technologies.

With CDMA, unlike other cellular telephone standards, subscriber data

change in real time,

depending on voice activity and requirements ofthe network and other users of the network.

Direct Sequence Spread Spectrum - DSSS

CDMA - In this method, the direct sequence(input data) which is spread

over a limited bandwidth is multiplied with a code or spreading

sequence (a pseudorandom sequence also known as PN

sequence).This will spread the input data over the entire bandwidth of

the communication channel. The power density is also reduced and is

spread over the frequency spectrum and hence is known as spread

spectrum method.



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CDMA MODULATION



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CDMA DE-MODULATION



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Mobile Internet Communication Technologies - EDGE

Mobile Communications: EDGE

Enhanced Data-rates for Global Evolution

Evolutionary path to 3G services for GSM and TDMAoperators

Builds on General Packet Radio Service (GPRS) air

interface and networks

Phase 1 (Release99 & 2002 deployment) supports best

effort packet data at speeds up to about 384 kbps

Phase 2 (Release2000 & 2003 deployment) will add

Voice over IP capability

EDGE is three to four times better and efficient then GPRS

technology. GPRS acquires four coding schemes while EDGEposses nine Modulation and Coding Schemes.


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Mobile Internet Communication Technologies - GPRS

GPRSis one of the technologies to improve 2G phones (second

generation phones) to enable them for transferring data at higher

speed, GPRS allows mobile phones to remain connected to network

and transfer requested or sent data instantly.

Mobile Communications:GPRS


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Mobile Internet Communication Technologies - VOIP

Mobile Communications: VOIP

VOIP stands for Voice over the Internet Protocol and is also

reffered to as IP Telephony.


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Mobile Internet Communication Technologies - VOIP

Mobile Communications: VOIP

M bil I C i i T h l i 2G


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Mobile Internet Communication Technologies2G

Began in the early 1990s and continues to be used

The main distinction between 1G and 2G arises because 2G

uses digital signals to carry voice

The label 2.5G is used for systems that extend a 2G system to

include some 3G features.

2.5G networks, such as General Packet Radio Service (GPRS), are an

extension of 2G networks, in that they use circuit switching for voice

and packet switching for data transmission resulting in its popularity

since packet switching utilizes bandwidth much more efficiently. In this

system, each users packets compete for available bandwidth, and

users are billed only for the amount of data transmitted.

Mobile Communications: 2G

M bil I t t C i ti T h l i 2G


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Some of the advantages that 2G had over 1G are:

The lower powered radio signals require less battery power, so phones

last much longer between charges, and batteries can be smaller.

The digital voice encoding allowed digital error checking which could

increase sound quality by increasing dynamic range and lowering the

noise floor.

The lower power emissions helped address health concerns.

Going all-digital allowed for the introduction of digital data services,such as SMS and email.

Greatly reduced fraud. With analog systems it was possible to have two

or more cloned handsets that had the same phone number.

Enhanced privacy. A key digital advantage not often mentioned is that

digital cellular calls are much harder to eavesdrop on by use of radioscanners. While the security algorithms used have proved not to be as

secure as initially advertised, 2G phones are immensely more private

than 1G phones, which have no protection against eavesdropping.

Mobile Communications: 2G

M bil I t t C i ti T h l i 3G


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A telecommunication hardware standards and general

Technology for mobile networking

It is based on the International Telecommunication Union (ITU)

family of standards

It conceived from Universal Mobile Telecommunication Service

(UMTS) concept for high speed networks for enabling variety of

data intensive applications

It consists of two main standardsCDMA 2000 & w- CDMA

3G network operators offer wide range of advanced service to

its users

This can be achieved by Spectral efficiency Serviceswide-

area wireless voice Telephone, videocalls, and broadband wireless, data all in a mobile

environment


3G APPLICATIONS


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3G APPLICATIONS

Interactive news delivery (voice, video, e-mail,

graphics) Voice /High-quality audio

Still photography

Video

Data transmission services

File transfer from intranet

Multimedia e-mail (graphics, voice, video)

Video conferencing

Web browser

On-line servicesTime schedules

Global Positioning Services/Geographical

Information Systems



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